A socio-technical study of water consumption and water conservation in Brazilian dwellings

A socio-technical study of water consumption

and water conservation in Brazilian dwellings

Daniel Richard Sant’Ana

Oxford Institute for Sustainable Development School of the Built Environment

Oxford Brookes University

A thesis is submitted in partial fulfillment of the requirements for the award of

Doctor of Philosophy

Oxford

January 2011

i

Abstract

This research arose from the need to reduce domestic water consumption in the Federal

District in a viable and cost-effective manner, so as to avoid water stress and promote

sustainable development through water demand management. The overall aim of this

research is to provide specific information regarding domestic water consumption in

order to adequately assess the feasibility of domestic water conservation measures for

Brazilian dwellings, with special attention to the different income ranges and dwelling

typologies in the Federal District. To address the hypothesis that variables such as

household income, dwelling typology and occupant behaviour affects the way water is

used, this research incorporated both quantitative and qualitative methodological

approaches to collect primary data on domestic water consumption in the Federal

District. Based on average values of primary data collected on public opinion,

awareness and acceptance of water conservation strategies, water end-use consumption

and dwelling characteristics; representative models were composed, and different

assessment techniques for the evaluation of water conservation measures were brought

together in order to identify feasible water conservation measures in terms of their

applicability, water savings and financial benefits for the different income ranges and

residential typologies of the Federal District. Findings from the study revealed that

variables of dwelling characteristics, income and occupant behaviour are directly related

and affect both indoor and outdoor water consumption patterns, and therefore, should be

considered for adequate water demand predictions, reuse system design dimensioning

and quantifying potential water-savings from conservation measures. It is also realised

that although water reuse systems are capable of promoting higher water savings than

water efficient strategies, water efficient strategies proved to be the most feasible water

conservation measures in terms of applicability and financial benefits, independent of

income level and dwelling typology.

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Acknowledgements

First of all, I would like to thank my director of studies Dr Rajat Gupta for his guidance,

kind advice and constant support throughout my research, which was determinant for

the accomplishment of the work presented in this thesis. It has been a real privilege and

an honour to have worked with him. My appreciation also goes to my supervisor

Professor Fergus Nicol, whose experience and constructive suggestions provided a firm

basis for the research. I would also like to express my most sincere gratitude to my co-

supervisor Dr Cláudia Amorim from the University of Brasília for her kind support and

for providing wonderful opportunities beyond the PhD for which I am truly grateful. I

have also been fortunate to have had the support and guidance from Professor Sue Roaf

in the initial stages of this work, whose words of wisdom have oriented the path of this

thesis.

Living between two countries can be difficult for a number of reasons, but it is also very

rewarding. My thanks also go to all my colleagues and friends I have made in these past

years in England and in Brazil. I would like to thank Maita Kessler and Harvey Brown

for some comforting thoughts of wisdom. I am also grateful to Stefan Preuss, Laura

Novo, Tim Jones, Nando Sigona, Andrew Inch and Martha, for some of unforgettable

moments in Oxford. I would also like to thank my closer friends from Brazil, to the

brothers, Túlio and Leandro Guimarães, Thiago Rigoletto and Nirceu Werneck; I

express my gratitude for their unconditional friendship throughout these years.

Last, but not least, I would like to express my eternal gratitude to my family, without

which I would not have come this far. I am incredibly grateful to my parents José and

Malú, my sister Tania and my wonderful niece Caroline for their constant support and

encouragement. But most of all, it is to my wife, Carol, who has been there for me at all

times; for her unconditional love, understanding and support for the pursuit of this goal.

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Table of Contents

1. Introduction ............................................................................................... 2

1.1 Background .......................................................................................................................... 2

1.2 Context of the research .................................................................................................... 3

1.3 Aim and objectives............................................................................................................. 5

1.4 Thesis structure .................................................................................................................. 6

1.4.1 Chapter 2: Domestic water consumption ........................................................ 6

1.4.2 Chapter 3: Domestic water conservation ......................................................... 6

1.4.3 Chapter 4: Methodology ......................................................................................... 6

1.4.4 Chapter 5: Baseline domestic water consumption ....................................... 7

1.4.5 Chapter 6: Evaluation of domestic water conservation measures ......... 7

1.4.6 Chapter 7: Conclusions and recommendations ............................................. 7

2. Domestic Water Consumption ............................................................. 9

2.1 Introduction ......................................................................................................................... 9

2.2 Water demand and supply ............................................................................................. 9

2.2.1 Global water outlook ................................................................................................ 9

2.2.2 Water in Brazil .......................................................................................................... 12

2.2.3 Water in the Federal District .............................................................................. 16

2.3 Variables of domestic water consumption ............................................................. 21

2.3.1 Cost of water ............................................................................................................. 21

2.3.2 Income ......................................................................................................................... 22

2.3.3 Household size.......................................................................................................... 23

2.3.4 Dwelling characteristics ....................................................................................... 24

2.3.5 Climate ......................................................................................................................... 25

2.3.6 Behaviour and perception ................................................................................... 26

2.3.6.1 Situational influences .................................................................................... 27

2.3.6.2 Unreasoned influences ................................................................................. 28

2.3.6.3 Reasoned influences ...................................................................................... 29

2.3.6.4 Awareness stimuli .......................................................................................... 29

2.4 Domestic water end-use consumption .................................................................... 30

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2.4.1 Building typology .................................................................................................... 35

2.4.2 Household income................................................................................................... 35

2.5 Water end-use frequencies and activities .............................................................. 38

2.5.1 Frequencies of water usage ................................................................................. 38

2.5.2 Water-consuming activities ................................................................................ 40

2.6 Conclusion ........................................................................................................................... 41

3. Domestic Water Conservation .......................................................... 44

3.1 Introduction ....................................................................................................................... 44

3.2 Water efficient strategies .............................................................................................. 44

3.2.1 Toilets .......................................................................................................................... 45

3.2.1.1 Waterless toilets.............................................................................................. 45

3.2.1.2 Low-flush toilets ............................................................................................. 46

3.2.1.3 Dual flush toilets ............................................................................................. 47

3.2.2 Water faucets ............................................................................................................ 48

3.2.2.1 Automatic faucets ........................................................................................... 48

3.2.2.2 Sensor faucets .................................................................................................. 49

3.2.3 Low-flow showerheads ......................................................................................... 50

3.2.4 Flow regulators ........................................................................................................ 51

3.2.5 High-efficiency washing machines ................................................................... 52

3.2.6 Pressure washers .................................................................................................... 54

3.2.7 Automatic shut-off nozzles .................................................................................. 55

3.2.8 Automatic irrigation systems ............................................................................. 56

3.2.9 Water leakage repair .............................................................................................. 57

3.3 Water reuse systems ....................................................................................................... 58

3.3.1 Rainwater harvesting systems ........................................................................... 62

3.3.1.1 Rainwater quality ........................................................................................... 63

3.3.1.2 System components and design ................................................................ 64

3.3.2 Grey water recycling systems ............................................................................. 70

3.3.2.1 Grey water quality .......................................................................................... 71


3.3.3 Wastewater reclamation systems ..................................................................... 76

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3.3.3.1 Wastewater quality ........................................................................................ 76


3.4 Conclusion ........................................................................................................................... 78

4. Methodological Approach .................................................................. 81

4.1 Introduction ....................................................................................................................... 81

4.2 Case study site selection ................................................................................................ 85

4.2.1 Administrative region selection ........................................................................ 85

4.2.1.1 The Federal District ....................................................................................... 85

4.2.1.2 Geo-demographic indicators ...................................................................... 86

4.2.1.3 Socio-economic indicators .......................................................................... 88

4.2.1.4 Dwelling typology ........................................................................................... 91

4.2.1.5 Selected administrative regions................................................................ 93

4.3 Primary data collection .................................................................................................. 95

4.3.1 Questionnaire survey ............................................................................................. 95

4.3.2 Domestic water auditing ...................................................................................... 96

4.4 Primary data analysis ..................................................................................................... 99

4.4.1 Baseline water consumption .............................................................................. 99

4.4.2 Statistical analysis ................................................................................................ 101

4.4.2.1 Drivers of domestic water consumption function .............................. 102

4.4.2.2 Price of water ................................................................................................ 103

4.4.2.3 Household income ....................................................................................... 104

4.4.2.4 Household size .............................................................................................. 105

4.4.2.5 Dwelling Characteristics ........................................................................... 105

4.4.2.6 Climate ............................................................................................................. 107

4.5 Evaluation of water conservation measures ...................................................... 108

4.5.1 Domestic water reductions .............................................................................. 108

4.5.1.1 Water efficient fittings, fixtures and appliances .............................. 109

4.5.1.2 Rainwater harvesting systems ............................................................... 110

4.5.1.3 Greywater recycling systems .................................................................. 111

4.5.1.4 Wastewater reclamation systems ......................................................... 112

4.5.1.5 Water reduction index ............................................................................... 113

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4.5.1.6 Water consumption scenarios ................................................................ 113

4.5.2 Applicability ........................................................................................................... 113

4.5.3 Cost-benefit analyses .......................................................................................... 114

4.5.3.1 Simple payback period .............................................................................. 114

4.5.3.2 Life cycle cost-benefit analysis ............................................................... 115

4.5.3.3 Average incremental cost-benefit analysis ........................................ 118

4.6 Conclusion ........................................................................................................................ 119

5. Domestic Water Baseline Consumption ...................................... 124

5.1 Introduction .................................................................................................................... 124

5.2 Primary data collection ............................................................................................... 124

5.3 Dwelling characteristics ............................................................................................. 125

5.3.1 Income ...................................................................................................................... 125

5.3.2 Household size....................................................................................................... 127

5.3.3 Tenure ....................................................................................................................... 127

5.3.4 Residential typology and amenity characteristics................................... 128

5.3.4.1 Lago Norte and Lago Sul: High income dwellings ........................... 128

5.3.4.2 Brasília and Águas Claras: Mid-high income dwellings ................ 129

5.3.4.3 Taguatinga and Candangolândia: Mid-low income dwellings .... 131

5.3.4.4 Ceilândia and Samambaia: Low income dwellings ......................... 131

5.3.5 Water fixtures and appliances in the home ............................................... 132

5.3.5.1 Bathroom fixtures ....................................................................................... 133

5.3.5.2 Kitchen fixtures and appliances ............................................................. 134

5.3.5.3 Utility fixtures and appliances ................................................................ 134

5.3.5.4 External taps .................................................................................................. 134

5.4 Domestic water consumption .................................................................................. 135

5.4.1 Annual water consumption .............................................................................. 135

5.4.2 Monthly water consumption ............................................................................ 136

5.4.3 Weekly water consumption ............................................................................. 138

5.4.4 Daily water consumption .................................................................................. 139

5.4.4.1 Water consumption per dwelling .......................................................... 139

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5.4.4.2 Water consumption per capita ............................................................... 140

5.4.5 End-use consumption ......................................................................................... 142

5.4.5.1 Indoor water consumption ...................................................................... 143

5.4.5.2 Outdoor water consumption ................................................................... 145

5.5 Water end-use frequencies and activities ........................................................... 148

5.5.1 Frequencies of water usage .............................................................................. 148

5.5.2 Water-consuming activities ............................................................................. 150

5.5.2.1 Dish washing ................................................................................................. 150

5.5.2.2 Clothes washing ........................................................................................... 151

5.5.2.3 Vehicle washing ............................................................................................ 151

5.5.2.4 Floor washing ................................................................................................ 152

5.5.2.5 Garden irrigation ......................................................................................... 152

5.5.2.6 Water reuse .................................................................................................... 153

5.6 Water-saving attitudes in the home ...................................................................... 155

5.7 Statistical evidence of water consumption ......................................................... 158

5.8 Conclusion ........................................................................................................................ 166

6. Evaluation of Domestic Water Conservation Measures ......... 169

6.1 Introduction .................................................................................................................... 169

6.2 Public Opinion, Awareness and Acceptance ....................................................... 169

6.2.1 Mains Water Metering and Tariff ................................................................... 169

6.2.2 Monthly Water Bill ............................................................................................... 170

6.2.3 Efficient Water Fittings, Fixtures and Appliances ................................... 174

6.2.4 Water Reuse Systems .......................................................................................... 176

6.2.4.1 Rainwater Harvesting Systems .............................................................. 176

6.2.4.2 Greywater Reuse Systems ........................................................................ 178

6.2.4.3 Wastewater Reuse Systems ..................................................................... 179

6.2.5 Dwelling Retrofit and Willingness-to-Pay .................................................. 180

6.2.6 Water Conservation Principals ....................................................................... 183

6.3 Domestic Water Efficiency ........................................................................................ 184

6.3.1 Building Adaptation............................................................................................. 184

6.3.2 Domestic Water Reductions ............................................................................. 185

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6.3.3 Cost-Benefit Analyses ......................................................................................... 196

6.4 Rainwater Harvesting Systems ................................................................................ 208




6.5 Greywater Recycling Systems .................................................................................. 229




6.6 Wastewater Reclamation Systems ......................................................................... 244




6.7 Summary and Conclusions ........................................................................................ 251

7. Conclusions and Recommendations ............................................. 255

7.1 Introduction .................................................................................................................... 255

7.2 Domestic water consumption .................................................................................. 255

7.3 Evaluation of domestic water conservation measures .................................. 258

7.4 Contribution to knowledge ....................................................................................... 262

7.5 Limitations of the study .............................................................................................. 264

7.6 Scope for further research ......................................................................................... 265

7.7 Implications of the findings ....................................................................................... 266

References 268

Appendices 280

Appendix A: House Survey Questionnaire 281

Appendix B: Flat Survey Questionnaire 286

Appendix C: House Water Audit Questionnaire 291

Appendix D: Flat Water Audit Questionnaire 297

Appendix E: Residential Building Block Survey 301

Appendix G: Diary-Tracking Cards 305

Appendix G: Diary-Tracking Summary Card 307

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Appendix H: Water Audit Inventory Form 309

Appendix I: Capital Costs of Automatic Irrigation System 313

Appendix J: Performance of Rainwater Harvesting Systems for High Income Dwellings 315

Appendix K: Performance of Rainwater Harvesting Systems for Mid-High Income Dwellings 321

Appendix L: Performance of Rainwater Harvesting Systems for Mid-Low Income Dwellings 327

Appendix M: Performance of Rainwater Harvesting Systems for Low Income Dwellings 333

Appendix N: Costs of Rainwater Harvesting Systems 338

Appendix O: Costs of Greywater Recycling Systems 363

Appendix P: Costs of Wastewater Reclamation Systems 377

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List of Figures

Figure 2.1 Per capita domestic water consumption projections for 2025. .................... 10

Figure 2.2 Change in water stress from 1995 to 2025 under a business as usual

scenario. .......................................................................................................................... 11

Figure 2.3 Brazil’s twelve hydrographic regions. .......................................................... 13

Figure 2.4 Population density (a) and surface water discharge rate (b) by hydrographic

regions in Brazil. ............................................................................................................. 14

Figure 2.5 Water availability per capita by hydrographic region. ................................ 14

Figure 2.6 Distribution of water demands in Brazil. ..................................................... 15

Figure 2.7 Hydrological sub-basins of the Federal District. ......................................... 17

Figure 2.8 Water supply systems of the Federal District. .............................................. 17

Figure 2.9 Deep wells used for ground water extraction in the Federal District. ......... 18

Figure 2.10 Projections of population growth for the Federal District. ........................ 19

Figure 2.11 Historical water consumption per capita in the Federal District. ............. 20

Figure 2.12 Average domestic water end-use consumption results of previous research.

......................................................................................................................................... 34

Figure 2.13 Per capita water consumption and social groups in the United Kingdom . 36

Figure 2.14 Monthly water consumption per income range in China ........................... 36

Figure 2.15 Average monthly water consumption by dwelling type and income range in

Australia .......................................................................................................................... 37

Figure 3.1 Tankless high-pressure flush valve toilet. ..................................................... 46

Figure 3.2 Dual flushing mechanisms for tank-style toilets (a) and tankless toilets (b) 47

Figure 3.3 Automatic bathroom faucet ........................................................................... 48

Figure 3.4 Sensor faucet operation ................................................................................ 49

Figure 3.5 Low-flow showerhead ................................................................................... 50

Figure 3.6 Wall-mounted (a) and terminally-fitted (b) flow regulators ......................... 51

Figure 3.7 Operating design and relative water levels of top-load, vertical-axis washing

machines (a) and front-load, horizontal-axis washing machines (b). ............................ 52

Figure 3.8 Washing machine with programmed settings to facilitate grey water reuse 53

Figure 3.9 Domestic pressure washer ............................................................................ 54

Figure 3.10 Automatic shut-off nozzle with multiple spray patterns .............................. 55

Figure 3.11 Automatic flow control device (a) and soil moisture sensor (b) ................. 57

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Figure 3.12 Conceptual flow diagram of water reuse system composition ................... 60

Figure 3.13 Potable and non-potable water header tank configuration ........................ 62

Figure 3.14 Generic composition of a rainwater harvesting system ............................. 65

Figure 3.15 Example of downpipe (a), subsurface (b) and floating (c) rainwater filters

......................................................................................................................................... 66

Figure 3.16 Gravity-fed grey water diversion system for sub-surface irrigation. ......... 73

Figure 3.17 Detailed cross-section of irrigation trench for sub-surface irrigation ....... 73

Figure 3.18 Generic composition of a GRW system....................................................... 74

Figure 3.19 Grey water reuse toilet and lavatory appliance unit .................................. 75

Figure 3.20 Small-scale treatment unit for wastewater reclamation ............................. 77

Figure 4.1 Flow diagram of the methodological approach ........................................... 84

Figure 4.2 Administrative Regions of the Federal District. ........................................... 86

Figure 4.3 Average domestic water consumption per capita (litres/person/day) .......... 88

Figure 4.4 Average dwelling monthly income in minimum wages ................................. 90

Figure 4.5 Relationship between income and water consumption ................................. 90

Figure 4.6 Relationship between built area and income ................................................ 92

Figure 4.7 Relationship between built area and water consumption ............................. 93

Figure 5.1 Income ranges of dwellings ........................................................................ 125

Figure 5.2 Dwelling income range per administrative regions. .................................. 126

Figure 5.3 Tenure of dwelling property by income group............................................ 128

Figure 5.4 Aerial view of high income houses in Lago Sul. ......................................... 129

Figure 5.5 Aerial view of mid-high income residential buildings in Brasília. ............. 130

Figure 5.6 Mid-high income residential buildings in Águas Claras. ........................... 130

Figure 5.7 Aerial view of mid-low income houses in Taguatinga ................................ 131

Figure 5.8 Aerial view of low income houses in Samambaia ....................................... 132

Figure 5.9 Average annual water consumption per dwelling ...................................... 135

Figure 5.10 Average monthly water consumption and precipitation ........................... 136

Figure 5.11 Average monthly water consumption and relative humidity .................... 137

Figure 5.12 Average monthly water consumption per income range .......................... 137

Figure 5.13 Average weekly water consumption patterns............................................ 138

Figure 5.14 Average weekly water consumption patterns per income range .............. 139

Figure 5.15 Scatter diagram of average daily water consumption per dwelling ......... 140

Figure 5.16 Scatter diagram of average daily water consumption per capita ............. 141

Figure 5.17 Average daily water consumption per capita by income range................ 141

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Figure 5.18 Average domestic water end-use consumption pattern at its simplest form

....................................................................................................................................... 142

Figure 6.1 Average dwelling monthly water bill per income group............................. 170

Figure 6.2 Resident’s opinion on the costs of mains water .......................................... 171

Figure 6.3 Incentive for water consumption reductions through progressive tariff .... 172

Figure 6.4 Resident’s opinion for charging an extra tariff for dwellings with

consumption above average .......................................................................................... 172

Figure 6.5 Residents’ opinion for providing discounts for dwellings with consumption

below average. .............................................................................................................. 173

Figure 6.6 Public opinion on additional water tariff destined towards investments on

water conservation practices and policies .................................................................... 174

Figure 6.7 Water efficient fittings fixtures or appliances within dwellings ................. 174

Figure 6.8 Public awareness of the existence of water efficient equipment ................. 175

Figure 6.9 Public acceptance over the use of water efficient equipment in the dwelling

....................................................................................................................................... 176

Figure 6.10 Public awareness of domestic rainwater harvesting systems ................... 177

Figure 6.11 Level of acceptance over the reuse of rainwater at home. ....................... 177

Figure 6.12 Public awareness of domestic greywater recycling systems ................... 178

Figure 6.13 Level of acceptance over the reuse of treated greywater at home............ 179

Figure 6.14 Public awareness of domestic wastewater reuse systems ......................... 179

Figure 6.15 Level of acceptance over the reuse of treated wastewater at home......... 180

Figure 6.16 Residents willing to adapt their home for water conservation ................. 181

Figure 6.17 Level of monthly investment for dwelling retrofit ..................................... 181

Figure 6.18 Duration of monthly investment for dwelling retrofit ............................... 182

Figure 6.19 Expected payback period of investments on dwelling retrofit .................. 183

Figure 6.20 Level of concern over the future of water resources ................................ 183

Figure 6.21 Level of importance to conserve water on a daily basis ........................... 184

Figure 6.22 Domestic water reductions per water efficient strategies for high income

dwellings ....................................................................................................................... 186

Figure 6.23 Domestic water reductions per water efficient strategies for mid-high

income dwellings ........................................................................................................... 187

Figure 6.24 Domestic water reductions per water efficient strategies for mid-low


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Figure 6.25 Domestic water reductions per water efficient strategies for low income

dwellings ....................................................................................................................... 189

Figure 6.26 Life cycle cost benefit analysis of feasible water efficient strategies for high


Figure 6.27 Life cycle cost benefit analysis of feasible water efficient strategies for mid-

high income dwellings ................................................................................................... 199


low income dwellings .................................................................................................... 199

Figure 6.29 Life cycle cost benefit analysis of feasible water efficient strategies for low


Figure 6.30 Average incremental cost benefit analysis of feasible water efficient

strategies for high income dwellings ............................................................................ 201


strategies for mid-high income dwellings ..................................................................... 202


strategies for mid-low income dwellings....................................................................... 202


strategies for low income dwellings .............................................................................. 203

Figure 6.34 Annual water savings per rainwater storage volumes for high income

dwellings ....................................................................................................................... 212

Figure 6.35 Annual water savings per rainwater storage volumes for mid-high income

dwellings ....................................................................................................................... 213

Figure 6.36 Annual water savings per rainwater storage volumes for mid-low income

dwellings ....................................................................................................................... 213

Figure 6.37 Annual water savings per rainwater storage volumes for low income

dwellings ....................................................................................................................... 214

Figure 6.38 Life cycle cost benefit analysis of feasible rainwater harvesting systems for



mid-high income dwellings ........................................................................................... 219

Figure 6.40 Average incremental cost of feasible rainwater harvesting systems for high


Figure 6.41 Average incremental cost of feasible rainwater harvesting systems for mid-


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List of Tables

Table 2.1 Average urban water consumption per capita by regions in Brazil for 2008.

......................................................................................................................................... 16

Table 2.2 Comparison of domestic water end-use data from different studies in the

world (% of total consumption). ..................................................................................... 32

Table 2.3 Comparison of indoor water end-use frequencies of previous studies .......... 39

Table 3.1 Estimated water loss from visible leaks ......................................................... 57

Table 3.2 Run-off coefficients relative to roof types....................................................... 65

Table 3.3 Water conservation measures considered for analysis .................................. 79

Table 4.1 Geo-demographic indicators .......................................................................... 87

Table 4.2 Socio-economic indicators ............................................................................. 89

Table 4.3 Dwelling Typologies in the Federal District .................................................. 92

Table 4.4 Summary of selected Administrative Regions for analysis ............................. 94

Table 4.5 Estimated life expectancies used for water efficient strategies. ................... 117

Table 4.6 Estimated life expectancies used for water reuse system components. ........ 117

Table 4.7 Methodological techniques for data collection and evaluation of water

conservation measures .................................................................................................. 119

Table 5.1 Average income per administrative regions ................................................. 126

Table 5.2 Number of residents per dwelling by income group .................................... 127

Table 5.3 Typological characteristics .......................................................................... 128

Table 5.4 Average flow rates and number of water fixtures and appliances ............... 133

Table 5.5 Indoor water end-use consumption per income range ................................. 147

Table 5.6 Outdoor water end-use consumption per income range .............................. 147

Table 5.7 End-use water consumption frequency per income range ........................... 148

Table 5.8 Actions taken in the last years to conserve water per income group ........... 157

Table 5.9 Actions residents are willing to take in order to reduce water consumption

....................................................................................................................................... 158

Table 5.10 Matrix of simple correlations ..................................................................... 160

Table 6.1 Domestic water tariffs per consumption ranges........................................... 170

Table 6.2 Potential water reductions per water efficient product for high income

dwellings ....................................................................................................................... 191

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Table 6.3 Potential water reductions per water efficient product for mid-high income

dwellings ....................................................................................................................... 192

Table 6.4 Potential water reductions per water efficient product for mid-low income

dwellings ....................................................................................................................... 193

Table 6.5 Potential water reductions per water efficient product for low income

dwellings ....................................................................................................................... 194

Table 6.6 Baseline water end-uses, and reduced water end-uses through water efficient

strategies applied to the different income dwellings ..................................................... 195

Table 6.7 Cost-benefit analyses of water efficient strategies for high income dwellings

....................................................................................................................................... 204

Table 6.8 Cost-benefit analyses of water efficient strategies for mid-high income

dwellings ....................................................................................................................... 205

Table 6.9 Cost-benefit analyses of water efficient strategies for mid-low income

dwellings ....................................................................................................................... 206

Table 6.10 Cost-benefit analyses of water efficient strategies for low income dwellings

....................................................................................................................................... 207

Table 6.11 Domestic water reductions promoted by rainwater harvesting systems for

high income dwellings in baseline and reduced water end-use consumption scenarios

....................................................................................................................................... 214


mid-high income dwellings in baseline and reduced water end-use consumption

scenarios ....................................................................................................................... 215


mid-low income dwellings in baseline and reduced water end-use consumption

scenarios ....................................................................................................................... 215


low income dwellings in baseline and reduced water end-use consumption scenarios 216

Table 6.15 Cost-benefit analyses of rainwater harvesting systems on a baseline water

end-use scenario for high income dwellings ................................................................. 222

Table 6.16 Cost-benefit analyses of rainwater harvesting systems on a reduced water



end-use scenario for mid-high income dwellings.......................................................... 224

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end-use scenario for mid-low income dwellings ........................................................... 225




end-use scenario for low income dwellings .................................................................. 227



Table 6.23 Baseline water end-use consumption scenario for greywater demand and

supply according to different types of reuse ................................................................. 235

Table 6.24 Reduced water end-use consumption scenario for greywater demand and

supply according to different types of reuse ................................................................. 235

Table 6.25 Annual domestic water savings promoted by greywater recycling systems

for different income typologies in baseline and reduced water end-use consumption

scenarios ....................................................................................................................... 236

Table 6.26 Cost-benefit analyses of greywater recycling systems on a baseline water


Table 6.27 Cost-benefit analyses of greywater recycling systems on a reduced water














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Table 6.34 Domestic water reductions promoted by wastewater reclamation systems for

different income typologies in baseline and reduced water end-use consumption

scenarios ....................................................................................................................... 245

Table 6.35 Cost-benefit analyses of wastewater reclamation systems on a baseline

water end-use scenario for high income dwellings ....................................................... 248

Table 6.36 Cost-benefit analyses of wastewater reclamation systems on a reduced

water end-use scenario for high income dwellings ....................................................... 248


water end-use scenario for mid-high income dwellings ............................................... 248


water end-use scenario for mid-high income dwellings ............................................... 249


water end-use scenario for mid-low income dwellings ................................................. 249


water end-use scenario for mid-low income dwellings ................................................. 249


water end-use scenario for low income dwellings ........................................................ 250


water end-use scenario for low income dwellings ........................................................ 250

Table 6.43 Feasible water conservation measures for the different income ranges .... 253

Chapter 1 Introduction

Introduction

2

1. Introduction

1.1 Background

“Water is essential for life” (Annan, 2005). It is the foundation of every life form in this

planet; to sustain water, is to sustain life. Our planet contains a limited amount of

accessible freshwater, of which only 0.01% of all water on Earth is useable for

ecological systems and humans (Shiklomanov, 1993). Freshwater provides mankind not

only with drinking water and sanitation, but also food, energy, transportation, recreation

and industrialized goods (Bidlack et al., 2004). However, as global population

increases, so does the demand for freshwater.

The rapid urbanization and expansion of industry and agriculture has led to the

overexploitation of freshwater reserves from natural systems (UN-Water, 2006; UNEP,

2006a). Traditionally, water bodies have been used as receptacles for waste disposal

(Kjellén and McGranahan, 1997) and as a result, freshwater supplies are being reduced

by pollution (UN/WWAP, 2003). Although it is still difficult to predict the exact impact

of climate change over the world’s freshwater supplies (IPCC, 2001), it has been

estimated that global warming will cause a 20% increase in global water scarcity

(UN/WWAP, 2003). Evidently, both quantitative and qualitative natures of global

freshwater reserves are being affected by human overexploitation, pollution and

climatic factors such as global warming.

Although Brazil contains the biggest freshwater reserve in the world, with an abundant

availability equivalent to 33,000 cubic meters per habitant per year (m3/hab/yr), this

resource is unequally distributed throughout the country (ANA, 2007). Seventy percent

of the country’s freshwater resources are located within the Amazon region, whose

population represents only 7% of the nation, while thirty percent of the available

freshwater, is destined to supply the remaining 93% of the population (Machado, 2003).

The Federal District has already started to present signs of water stress. A region is said

to experience water stress when water supplies are below 1,700 m3/hab/yr (Falkenmark

and Lindh (1976), cited in IPCC (2001), and according to Tundsi (2005), the Federal

District has reached a water availability index equivalent to 1,555 m3/hab/yr. As the

population increases (IBGE, 2009) and per capita water consumption grows (CAESB,

Introduction

3

2002; CAESB, 2004; CAESB, 2006; CAESB, 2008), the Federal District’s capacity to

supply potable water has diminished, and new freshwater resources are having to be

drawn from far away. Clearly, this is a sign that water is running out, or at least

becoming less plentiful (Rijsberman and Cosgrove, 2000).

It seems that the Federal District’s water resource management is being merely focused

on a supply-driven approach, through the production of new water supply systems

according to public demand. However, to achieve a sustainable water management and

meet the needs of the present without compromising the ability of future generations to

meet their own needs (UN, 1987), it is crucial to understand what lies behind water

consumption and to be aware of how water is being used to adequately manage demand

through an integrated approach, including both demand-side and supply-side water

conservation measures.

1.2 Context of the research

As opposed to supply management, whose main strategy is to increase water supply to

meet demand, water demand management focuses in the control of water consumption

through educational, economic, regulatory and water conservation measures, to

postpone or avoid the need to develop new water supply systems (Butler and Memon,

2006). The use of decentralized supply-side and demand-side water conservation

measures in buildings have been reported to promote water reductions through

efficiency and reuse (EA, 2008b; Griggs et al., 1998; Vickers, 2001; Waterwise, 2008).

Water efficient fittings, fixtures and appliances are capable of promoting water

conservation through the improved effectiveness of water usage (Grant, 2006; Griggs

and Burns, 2009; Heinrich, 2007; Schmidt, 2004). Water reuse systems, on the other

hand, make use of alternative sources of water supply such as rainwater, greywater and

wastewater, for non-potable end-uses such as irrigation, toilet flushing and washing of

floors, vehicles and clothes (ANA et al., 2005; Asano et al., 1986; Gaulke, 2006;

Leggett et al., 2001a).

However, in order to adequately evaluate potential water savings of both demand-side

and supply-side water conservation measures, firstly, it is important to quantify the

Introduction

4

volume of water consumed by each major points of water usage, and understand how

water is being used by occupants (De Oreo et al., 1996; Jorgensen et al., 2009).

Previous studies have shown that domestic water consumption varies according to a

series of factors, including dwelling characteristics1, socio-economic factors, climate

and occupant behaviour (i.e. Arbués et al., 2003; Dziegielewski et al., 1993; Jorgensen

et al., 2009; Troy and Randolph, 2005). Such elements can vary from place-to-place,

leading to differences in water consumption patterns. For example, countries with

different national income are most likely to contain distinct patterns of domestic water

consumption. Although numerous studies have fully analysed domestic water

consumption in developed countries, little research has been carried out within

developing economies (see Potter and Darmame, 2010; Sivakumaran and Aramaki,

2010; Zhang and Brown, 2005).

Moreover, no study has explored the variations of domestic water consumption in case

of high difference in household2 income, especially within the Brazilian context, where

social inequality is high. To date, there have been very few rigorous studies concerning

domestic water end-use consumption in Brazil, and no generalizable data has been

produced. Research carried out so far, has been limited to two houses and three multi-

storey buildings in Southern Brazil (Ghisi and Ferreira, 2007; Ghisi and Oliveira, 2007)

and one flat and seven houses in São Paulo (Barreto, 2008; Rocha et al., 1998). In short,

in Brazil there is currently insufficient information regarding domestic water end-use

consumption for different income ranges and dwelling typologies in order to adequately

assess the performance of domestic water conservation measures.

The characterization of domestic water end-use consumption has led to a series of

investigations that have evaluated the potential water savings (Brewer et al., 2001;

Griggs et al., 1998; Maddaus, 1984; Mayer et al., 2003) and the economics of a range of

domestic water conservation measures in developed nations (Arpke and Strong, 2006;

EA, 2003; EA et al., 2007; Marshallsay et al., 2007; Rahman et al., 2010; Roebuck et

al., 2010; Waterwise, 2008). These countries, however, present a socio-economic reality

different from that found in developing countries.

1 This study refers to the term dwelling as a unit of the home, a house or flat. 2 The term household is referred to as a group of people, often a family, who live together.

Introduction

5

Little is known about the feasibility of domestic water conservation measures in

developing economies. In Brazil, the few studies on water conservation that have been

carried out, were for specific strategies (ANA et al., 2005; Ghisi, 2006; Ghisi et al.,

2007; Ghisi and Ferreira, 2007; Ghisi and Oliveira, 2007; Oliveira, 2002; Vimieiro and

Pádua, 2005). Furthermore, only one work has looked into the financial benefits of

rainwater harvesting systems in Brazil (Júnior et al., 2008). These studies fail to

evaluate the potential water savings and financial benefits for both supply-side and

demand-side water conservation measures according to household income and dwelling

typology.

Further work is needed to evaluate the feasibility of domestic water conservation

measures in terms of their applicability, water savings and financial benefits, according

to household income and building typology.

1.3 Aim and objectives

With these issues in mind, the overall aim of this research is to provide specific

information regarding domestic water consumption in order to adequately assess the

feasibility of domestic water conservation measures for Brazilian dwellings, with a

special attention to the different income ranges and dwelling typologies in the Federal

District. Therefore, the main objectives of this research are:

1. To measure current domestic water consumption and understand how water is

being used by residents of different income ranges and dwelling typologies in

the Federal District; and

2. To assess water end-use patterns for the different income ranges and dwelling

typologies; and

3. To identify and evaluate the feasibility of domestic water conservation measures

in terms of their applicability, water savings and financial benefits for different

income ranges and residential typologies.

Introduction

6

1.4 Thesis structure

The structure of the thesis reflects the stated aim and objectives, and logically

progresses through the steps required to meet them. The following sections provide a

brief description of each chapter (excluding Chapter 1).

1.4.1 Chapter 2: Domestic water consumption

The thesis starts out with a global review of water demand and supply, funnelling into

the Federal District’s freshwater availability and demand, and appraising its current

water resource management and future demand predictions. This chapter reviews the

main variables of domestic water consumption, including the cost of water, income,

household size, dwelling characteristics, climate and behaviour and perception. A

comparative review of previous studies was carried out and factors such as building

typology, household income and water end-use frequencies and activities examined.

1.4.2 Chapter 3: Domestic water conservation

Chapter 3 consists of a detailed review of the state of the art demand-side and supply-

side water conservation technologies for residential buildings3 available in the Brazilian

market. A range of water efficient products are identified and their reduced flow rates

and potential water reductions addressed. Furthermore, an overview of commercially

available rainwater harvesting, greywater recycling and wastewater reclamation systems

is carried out providing a description of their components and system design.

1.4.3 Chapter 4: Methodology

Chapter 4 provides a full description of the methodological approach applied to assess

current domestic water consumption and identify water end-use patterns for the

different income ranges and dwelling typologies in the Federal District. This chapter

describes the case study selection, primary data collection and analysis, as well as the

methods and equations used to identify feasible water conservation measures in terms of

applicability, water savings and financial benefits.

3 Residential buildings are referred in this study as the construction composed of one or more dwellings.

Introduction

7

1.4.4 Chapter 5: Baseline domestic water consumption

Chapter 5 addresses the first objective. It analyses results obtained from fieldwork and

evaluates domestic water consumption and water end-use patterns for different

residential building types of high, mid-high, mid-low and low income dwellings,

exploring the way occupant behaviour has a direct influence over the way water is used

at home. Based on a set of explanatory variables, multiple regression analysis is carried

out and indoor and outdoor water demand functions are estimated.

1.4.5 Chapter 6: Evaluation of domestic water conservation measures

Addressing the second objective, Chapter 6 builds on the information presented in

Chapter 3 and applies the primary data from Chapter 5 in order to identify feasible

domestic water conservation measures in terms of their applicability, water savings and

financial benefits taking into account for public opinion, awareness and acceptance of

water conservation strategies, water end-use consumption and dwelling characteristics

for the different income ranges and residential typologies of the Federal District.

1.4.6 Chapter 7: Conclusions and recommendations

Chapter Seven summarises the investigation undertaken, draws some conclusions,

outlines the contributions to knowledge, highlights the potential for further work and

states the implications of the findings.

Chapter 2 Domestic Water Consumption

Domestic Water Consumption

9

2. Domestic Water Consumption

2.1 Introduction

As a starting point, this chapter provides a global outlook of water demand and

examines the issues affecting world water supplies. It goes over Brazil’s natural

freshwater reserves and reviews the country’s water uses, focusing on domestic water

demand. Then, it evaluates the Federal District’s water availability and appraises current

management of water resources for future water demand. This chapter reviews the main

drivers of domestic water consumption such as the cost of water, household income,

dwelling characteristics, climate and occupant behaviour, in order to understand what

lies behind domestic water consumption. Finally, a comparative review of previous

domestic water end-use studies was carried out and factors such as building typology,

household income and water end-use frequencies and activities were examined.

2.2 Water demand and supply

Water is a key element that provides society with an in-stream of benefits such as food

production, energy production, consumer goods, drinking water, hygiene, sanitation,

etc. The overuse of freshwater resources linked with global factors as climate change

and pollution have been affecting both quantity and quality of water supply. This

section examines freshwater reserves and appraises demand from global to regional

perspectives.

2.2.1 Global water outlook

For years human beings have been exacerbating fresh water supplies as an inexhaustible

resource, strongly depending upon its regenerative capacity offered by the hydrological

cycle. However, it is important to remind ourselves that our planet contains a finite

quantity of water, where 97.5% of the supply can be found within the oceans in the

form of saltwater and only 2.5% is fresh. Most of this fresh water is of difficult access,

in the form of ice within the Polar Regions and mountains or groundwater including soil

moisture, swamp water and permafrost. Only 0.01% of all water on Earth is useable for

eco-systems and humans (Shiklomanov, 1993).


10

To meet the needs of society, freshwater extracted from natural resources is used to

supply water for agriculture, industry, commercial and domestic uses, providing an in-

stream of benefits such as food production, energy production, consumer goods,

drinking water, hygiene, sanitation, recreation, among others (Bidlack et al., 2004).

However, as global population increases, so does the demand for water. The trend

towards the rapid urbanization, the expansion of industry and irrigated agriculture has

led to increased extractions of freshwater for a demand that now exceeds supply in

many countries in the world, leading to excessive pressure on the environment (UN-

Water, 2006; UNEP, 2006b).

In 1995 the world withdrew the equivalent of 3,906 km3 of freshwater, and according to

Rosegrant et al. (2002), water withdrawal is projected to increase by at least 50% more

by 2025. The authors highlight the fact that a rapid population growth will lead to an

increase of total domestic water consumption per capita by 71%, of which more than

90% will be in developing countries (Figure 2.1).

Figure 2.1 Per capita domestic water consumption projections for 2025.

Source: Rosegrant et al. (2002)

UN-Water (2006) reports that while global water consumption has been growing at

more than twice the rate of population growth, freshwater availability is being affected

by pollutant charges of effluents from the expanding urban, industrial and agricultural

uses. Traditionally, rivers, lakes and coastal waters have been used as receptacles for

diluting and dispersing wastes (Kjellén and McGranahan, 1997), however, water bodies

have a limited capacity to process pollutant charges. According to the UN’s World


11

Water Development Report (UN/WWAP, 2003), freshwater supplies are being reduced

by pollution. The report indicates that an estimated 2 million tons of waste are disposed

of within water bodies on a daily basis, affecting the equivalent of 12,000 km3 of

freshwater worldwide.

There is undeniable evidence that climate change will have an impact over the

hydrological cycle, and consequently, over freshwater supplies (IPCC, 2001). Although

it is difficult to predict future changes in precipitation patterns, projected climate change

impacts include the increased frequency of heavy rainfall, which may lead to floods in

many areas of the world, and extreme droughts in semi-arid and arid regions of the

world (IPCC, 2007). It has been estimated that climate change will account for about

20% of the increase in global water scarcity (UN/WWAP, 2003).

It is evident that the overuse of freshwater resources linked with global factors as

climate change and pollution are affecting both quantity and quality of water supply.

Predictions point out that many of today’s developing economies in Latin America,

Africa and Asia, will experience increasing pressure on water resources (Figure 2.2).

Furthermore, under a business as usual scenario, many countries will face water deficit

(Rijsberman and Cosgrove, 2000).

Figure 2.2 Change in water stress from 1995 to 2025 under a business as usual scenario.

Source: Rijsberman and Cosgrove (2000)


12

Climate change will also affect domestic water consumption. The impact of climate

change on domestic water consumption depends upon the consumer’s behaviour and

regulatory changes. Downing et al. (2003) suggest that the annual additional impact of

climate change on domestic demand of eight regions of England and Wales is an

increase of about 1.0 - 1.5% for the 2020’s and 1.5 – 3.0% by 2050’s. They conclude

that the main components of water consumption sensitive to climatic changes are

personal wash, garden watering and car washing.

2.2.2 Water in Brazil

In Brazil, current pressure upon national water resources is a product of population and

economic growth, expressed in high rates of urban expansion and worrisome levels of

water pollution, together with growing episodes of floods and droughts, affecting both

quantity and quality of available freshwater supplies (ANA, 2002). In order to face the

challenge of solving such issues related to the increase of water demand for urban,

industrial and agricultural uses, water stress caused by supply vs. demand, and of

environmental degradation of freshwater resources in Brazil, the Agência Nacional das

Águas - ANA (National Water Agency), was created in 2000, as a means to manage

Brazil’s water basins and to advert an impending water crisis (ANA, 2002).

To manage Brazil’s natural water resources, the country was divided into twelve

hydrographic regions, each composed according to a water basin or group of contiguous

water basins within its national territory (Figure 2.3). A ratio between mean surface

water discharge rates (renewable water supply) and population (water demand) is often

used by the United Nations as an indicator for benchmarking water availability, and in

this sense, Brazil presents an abundant freshwater availability equivalent to 33,000

cubic meters per habitant per year (ANA, 2007).

But, although Brazil contains the biggest freshwater reserve in the world, with a total

renewable water resource equivalent to 5,418 km3 (UN/WWAP, 2003), this reserve is

unequally distributed throughout the country. According to Machado (2003), seventy

percent of Brazil’s freshwater supply is situated within the Amazon water basin, whose

population represents only 7% of the country’s total population, whilst the remaining

thirty percent of freshwater available, is destined to supply the other 93% of the

population.


13

Figure 2.3 Brazil’s twelve hydrographic regions.

Source: ANA (2007)

Figure 2.4(a), illustrates population density per hydrographic region, and in general, low

population densities can be found within the Amazon, Tocantins/Araguaia and Paraguay

hydrographic regions (ANA, 2002). High population densities are found in the coastal

regions of Northeast and Southeast Brazil. Figure 2.4(b), shows us that the average

surface water discharge rate per hydrographic region is bigger in Northern and Southern

Brazil, while North-eastern Brazil and the Paraguay water basin presents the lowest

discharge rates.

By cross-referencing population density and surface water discharge rates, water

availability indicators for each hydrographic region is found in Figure 2.5 (ANA, 2002).

Spatial variations of water availability per capita can be observed, and overall, low rates

of water availability are associated with high population density and poor levels of

surface water resource. In one hand, the highest water availability rates are located in

the North region of Brazil, within the Amazon water basin, where the number of

habitants is low and surface water discharge is high. Poor levels of water availability

rates are found within coastal regions of North-eastern Brazil where population


14

densities are high, and water resources are low. In particular, specific regions of São

Paulo and Rio de Janeiro presented poor levels of water availability per capita.

Although these regions present medium rates of surface water discharge, urban densities

within these regions are extremely high, leading to high demands of freshwater for

domestic, industrial, agricultural and livestock uses.

Figure 2.4 Population density (a) and surface water discharge rate (b) by hydrographic regions in Brazil.

(a) (b)

Source: ANA (2002)

Figure 2.5 Water availability per capita by hydrographic region.

Source: ANA (2002)


15

Figure 2.6 shows the distribution of water uses in Brazil (ANA, 2007). Although the

major demand of freshwater is for agriculture (46%), noticeably, domestic water

consumption represents the second largest demand (26%), followed by industrial (18%)

and livestock (7%) water uses.

Figure 2.6 Distribution of water demands in Brazil.

Table 2.1 on the next page shows the average urban water consumption per capita for

the five regions of Brazil for 2008 (SNSA, 2010). Through a cross-regional comparison

of domestic water per capita demand, the state of Alagoas presents the lowest

consumption rate with 89 litres per person per day (l/p/d), followed by Pernambuco,

with 90 l/p/d, and Paraíba with 92 l/p/d. The state of Rio de Janeiro has the highest

rate of domestic water consumption per capita equivalent to 236 litres per person per

day, followed by São Paulo and the Federal District, both with 176 l/p/d.

Agricultural46%

Domestic29%

Industrial18%

Livestock7%

Source: ANA (2007)


16

Table 2.1 Average urban water consumption per capita by regions in Brazil for 2008.

Region / State Per Capita

Consumption Region / State

Per Capita

Consumption

No

rth

Acre 144 l/p/d

No

rth

-Ea

st

Alagoas 89 l/p/d

Amazonas 134 l/p/d Bahia 122 l/p/d

Amapá 161 l/p/d Ceará 131 l/p/d

Pará 147 l/p/d Maranhão 104 l/p/d

Rondônia 107 l/p/d Paraíba 92 l/p/d

Roraima 134 l/p/d Pernambuco 90 l/p/d

Tocantins 123 l/p/d Piauí 110 l/p/d

So

uth

-Ea

st Espírito Santo 85 l/p/d R. Grande do Norte 116 l/p/d

Minas Gerais 138 l/p/d Sergipe 118 l/p/d

Rio de Janeiro 236 l/p/d

Ce

ntr

al-

We

st

Federal District 176 l/p/d

São Paulo 176 l/p/d Goiás 126 l/p/d

So

uth

Paraná 128 l/p/d Mato Grosso do Sul 126 l/p/d

Rio Grande do Sul 145 l/p/d Mato Grosso 166 l/p/d

Santa Catarina 141 l/p/d BRAZIL 151 l/p/d

Source: SNSA (2010)

2.2.3 Water in the Federal District

The Federal District lies within the dividing boarders of the Paraná,

Tocantins/Araguaia and São Francisco hydrographic regions. Figure 2.7 on the next

Page illustrates the Federal District’s hydrological sub-basins: (i) LagoParanoá, (ii) Rio

Corumbá, (iii) Rio Descoberto, (iv) Rio Maranhão, (v) Rio Preto, (vi) Rio São

Bartolomeu and (vii) Rio São Marcos. Both surface and ground water resources from

these sub-basins are used to supply potable water to the existing population.

The Companhia de Sabeamento Ambiental do Distrito Federal-CAESB (Environmental

Sanitation Company of the Federal District) is responsible for public water supply and

sewage treatment within the territory, and operates five main surface water supply

systems: (i) Descoberto, (ii) Torto-Santa Maria, (iii) Planaltina-Sobradinho, (iv)

Brazlândia and (v) São Sebastião (Figure 2.8).

Figure 2.7 Hydrological sub

Figure 2.8 Water supply systems of the Federal District.


Hydrological sub-basins of the Federal District.

Source: ANA (n.d.)

Water supply systems of the Federal District.

Source: CAESB (2006)


17


18

However, the available surface water supplies reached their maximum capacity of

extraction for potable water production to the constant-growing population of the

Federal District. The discovery of high-yield aquifers within the region, allied with the

need to raise productivity and the saturation of existing surface water resources, the

water facility company embraced a new concept of ground water extraction through the

use of deep water wells, and in 2003 the company initiated the process of incorporating

ground water extraction to the supply system (CAESB, 2008).

Today, there are a total of 109 deep wells located throughout the Federal District

(Figure 2.9) composing eight supply sub-systems: Água Quente (in purple); São

Sebastião (in green); Sobradinho (in yellow); INCRA-08 (in blue); Papuda (in cyan);

Jardim Botânico (in red); Itapoão (in light green) and Arapoanga (in bright purple).

Figure 2.9 Deep wells used for ground water extraction in the Federal District.


Although industrial activities within the Federal District are insignificant to water

demand, irrigation levels are growing within the region. From the existing 121,761.72

hectares of cultivated land, 14% is being irrigated for agricultural production

(EMATER, 2004). With a water consumption rate equivalent to 7,174 litres per second

per day (CAESB, 2008), domestic water consumption has been raising proportionally

with the growing population.

Figure 2.10 Projections of population growth

Source: CAESB and MEL (2004); IBGE as cited by Generino

Figure 2.10 shows the evolution of population growth in the Federal District from 1957

to 2010 and projectio

as cited by Generino, 2006). According to IBGE

District is 2,606,885 inhabitants, and estimates indicate a high annual growth rate of

2.51% a year (RIPSA, 2010)

Per capita water consumption figures indicate a constant raise in water demand in the

last years (Figure 2.11). Historical water consumption figures available

2008, indicate an increase from 207 l/p/d to 301 l/p/d, a growth rate of 13.4 l/p/d per

year, in the Federal District

2008).

Clearly, the Federal Distr

resources and water stress levels are being breached. Today, the Federal District’s sub

basins provide a total renewable surface water discharge rate of an estimated 2

litres/sec/km2 (CAESB, 2008; CODEPLAN, 2007)

availability indicator is equivalent to 1,555 m

Falkenmark and Lindh (1976), as cited in IPCC

experience water stress when water supplies are below 1,700


Projections of population growth for the Federal District.

Source: CAESB and MEL (2004); IBGE as cited by Generino (2006)


to 2010 and projections for the years 2020 and 2030 (CAESB and MEL (2004); IBGE

as cited by Generino, 2006). According to IBGE (2009) the population of the Federal


(RIPSA, 2010).


last years (Figure 2.11). Historical water consumption figures available


year, in the Federal District (CAESB, 2002; CAESB, 2004; CAESB, 2006; CAESB,

Clearly, the Federal District’s population is putting pressure upon its natural water

resources and water stress levels are being breached. Today, the Federal District’s sub


(CAESB, 2008; CODEPLAN, 2007). The Federal District’s water

availability indicator is equivalent to 1,555 m3/inh/yr (Tundisi, 2005)

Falkenmark and Lindh (1976), as cited in IPCC (2001), a country or region is said to

experience water stress when water supplies are below 1,700 m3/inh/yr.


19

for the Federal District.

(2006)


ns for the years 2020 and 2030 (CAESB and MEL (2004); IBGE

the population of the Federal



last years (Figure 2.11). Historical water consumption figures available from 2002 to


(CAESB, 2002; CAESB, 2004; CAESB, 2006; CAESB,

ict’s population is putting pressure upon its natural water

resources and water stress levels are being breached. Today, the Federal District’s sub-


. The Federal District’s water

(Tundisi, 2005). According to

, a country or region is said to

/inh/yr.


20

Figure 2.11 Historical water consumption per capita in the Federal District.

Data obtained from (CAESB, 2002; CAESB, 2004; CAESB, 2006; CAESB, 2008)

Future projections estimate that by 2020, domestic water demand in the Federal District

will raise to 13,800 litres of water per second per day (l/s/d), and by the year 2030, this

demand will reach 16,600 l/s/d (CAESB and MEL, 2004). However, the available

freshwater systems are limited to supply water at a total discharge rate of 11,809 l/s/d

(CAESB, 2008). Evidently, the population growth and high per capita demand in the

Federal District will have a great impact upon the total demand for freshwater in a

business-as-usual scenario.

To meet the needs of such excessive water demand forecasts, the water facility company

intends to use freshwater resources from Ribeirão do Bananal, Lake Paranoá and

Corumbá IV, and has obtained environmental permission to deploy three new water

supply systems in the coming years (CAESB, 2008). Lake Paranoá is an artificial

landmark, part of UNESCO’s world heritage sites, created during Brasilia’s

construction as means of achieving environmental comfort by raising the levels of

relative humidity in the air and to serve as a place for recreation (Santos, 2008), not for

public water supply. Corumbá IV is a hydroelectric power plant recently built within the

state of Goiás, 122 km from the Federal District (Corumbá-Concessões, 2010), and this

will imply in high costs for water transportation.

There are clear indications that, owning to the high increasing demand for water, the

Federal District has seen its capacity for generating its own resources diminished and

207

249

283301

0

50

100

150

200

250

300

350

2002 2004 2006 2008

litres per person per day


21

new freshwater resources have to be drawn from far away. This is a sign that water is

running out, or at least becoming less plentiful in places where population and per

capita water consumption grow, damaging the ecosystems from which it is drawn

(Rijsberman and Cosgrove (2000). It is evident that water resource management is

being focused exclusively on an engineering supply-side approach through the

redistribution of freshwater to where and when people want it for their use and the

demand side strategy has been ignored. In order to achieve a sustainable water

management in the Federal District, we need to understand what lies behind water

consumption and be aware of how water is being used to adequately manage existing

natural resources within an integrated framework, including both supply-side and

demand-side water conservation measures.

2.3 Variables of domestic water consumption

This section aims to understand what lies behind domestic water consumption and

review the main drivers of domestic water consumption. Numerous studies have

demonstrated that variables such as the cost of water, household income, climate,

dwelling characteristics, and occupant behaviour affect the way water is used and

should therefore be considered for water demand predictions.

2.3.1 Cost of water

A great deal of economic research has been carried out over pricing policies as a

mechanism for managing domestic water consumption. The essential logic behind the

theory is that the higher the cost of water, the lower domestic water consumption is

(Shaw, 2005). This makes sense if water is considered as a pure economic good,

however, according to Savenije (2002), water is not a normal economic good. It

contains a number of characteristics which makes it unique. Liu et al. (2003) argues that

the different uses of water, have different levels of economic values. For example, in an

extreme case, water, as a basic human need for survival, ceases to be an economic good.

On the other hand, once basic needs have been satisfied, surplus water can be

considered an economic good.

Numerous studies have shown that domestic water consumption tends to be price-

inelastic, and the decrease in consumption is lower than the increase in cost (see


22

Worthington and Hoffman, 2008). Arbués (2003) argues that in most cases water

demand is inelastic due to the fact that there are no substitutes for water and because

there is a low level of consumer perception on rate structures, since these represent a

very small fraction of household income.

It has been observed, however, that price elasticity varies according to a given use

(Conley, 1967). Essential water uses (i.e. drinking, cooking, personal hygiene, etc.) are

not affected by the cost of water and have low price elasticity. As a result, price increase

is expected to result in a small decrease in consumption. On the other hand, unessential

water uses (i.e. landscape irrigation, car washing, swimming pools, etc.) are usually

affected by the cost of water and have a higher elasticity. As a result, price increase

would lead to changes in the way unessential water is used, or even, to the use of

alternative sources of water, in order to reduce consumption (Corbella and Pujol, 2009;

Schleich and Hillenbrand, 2009).

The efficiency of pricing policies is dependent upon the price elasticity of domestic

water consumption, where, the higher the elasticity, the more effective the policies are

(Arbués et al., 2010). Empirical studies indicate that consumer-response to changes in

the cost of water is correlated with a series of explanatory variables affecting domestic

water demand (Espey et al., 1997).

Within this context, a series of econometric models for domestic water demand

estimations (Qd) have been derived following the simple form in Equation 2.1, which

relates water consumption in function of price (P) and other factors (Z) such as income,

household type and household composition (Arbués et al., 2003).

�� = ��, � (2.1)

Qd = Domestic Water Demand P = Price Z = Other Independent Variables

2.3.2 Income

Numerous econometric models have been estimated by making use of income as an

independent variable of water demand function in order to identify adequate price rate

structures for water charging (i.e. Agthe and Billings, 1987; Billings and Agthe, 1980;


23

Dalhuisen et al., 2003; Hewitt and Hanemann, 1995; Niewswiadomy and Molina,

1989). Per capita income is commonly applied to models which make use of aggregated

water consumption data at the neighbourhood level, however, at the household-scale,

property value can be used as a substitute of household income because of their high

correlation (Dandy et al., 1997).

Generally, income is a measure of purchase power and is commonly associated with

living standards and level of education. Income can have an effect over the perception

of water cost. High income households might not be as responsive to water pricing as

low income households (Agthe and Billings, 1987). Living standards and property

characteristics is also affected by income. The basic premise is that the higher the

income, the higher the number of water-consuming features in the household. Wealth

can be associated with the presence of a higher number of water fixtures and appliances,

larger gardens and swimming pool, affecting the way water is used (Corbella and Pujol,

2009). On the other hand, income has a positive correlation with education, and

therefore might be responsive to water conservation measures taken by residents

through the purchase of water-saving equipment and adopting water drought-tolerant

garden vegetation (Worthington and Hoffman, 2008).

Worthington and Hoffman (2008) point out that estimates of income elasticity in the

literature indicate that domestic water consumption is income inelastic and small in

magnitude. Although results are consistent with income inelasticity, sample bias might

have a role to play. The authors argue that most studies were carried out in populations

with similar household income, and that domestic water demand might prove to be

income-elastic in an income-diverse situation, such as those found in developing

economies.

2.3.3 Household size

Daily per capita consumption (litres per person per day) is a common performance

indicator used to benchmark and forecast domestic water consumption (Wong and Mui,

2008). If domestic water consumption is measured at the household level, the number of

residents should have a positive association with water use, since occupancy has a direct

influence on water consumption. Studies demonstrate that household size is correlated


24

with domestic water consumption (i.e. Arbués et al., 2010; Barrett and Wallace, 2009;


It is expected that, the larger the number of residents in a household, the bigger the

consumption will be. However, it has been found that the increase in domestic water

consumption is less than proportional to the increase in household size (Arbués et al.,

2003; Worthington and Hoffman, 2008).

Research focused on household size and domestic water consumption indicated that

domestic water consumption per capita is inversely related to the number of residents in

a dwelling (Arbués et al., 2010). Such aggregated statistical analysis of household size

and domestic water consumption per capita suggests that the greater the number of

residents in a dwelling, the lower the rate of per capita consumption. This indicates that

domestic water consumption is not only associated with the number of persons in a

household, but also with other communal uses (i.e. irrigation, cleaning, washing,

swimming pool, etc.).

2.3.4 Dwelling characteristics

Dwelling characteristics such as building typology, built area, garden area and water-

using facilities might influence the way water is used, and therefore affect the amount of

water consumed in a household.

A series of studies indicate that domestic water consumption varies according to

residential building typology (i.e. Fox et al., 2009; Loh and Coghlan, 2003; Russac et

al., 1991; Thackray et al., 1978; Troy and Holloway, 2004; Zhang and Brown, 2005).

Some findings suggests that water consumption rates between the different dwelling

typologies are not significantly different from each other (Troy and Holloway, 2004;

Zhang and Brown, 2005). However, according to Fox et al.(2009) a significant

relationship between physical property characteristics and domestic water consumption

can be found. An investigation carried out by Russac et al. (1991) found that water

consumption was higher in detached houses and lower in flats.


25

A study focusing on indoor and outdoor domestic water usage for single and multi-

storey and dwellings found that multi-storey dwellings used less water than single

residential dwellings (Loh and Coghlan, 2003). This might be attributed to the

typological characteristics of residential multi-storey buildings, since flat dwellings

contain communal garden areas, and therefore can have a lower water consumption rate

on outdoor activities than house dwellings with individual gardens.

In most water use studies, outdoor water use is exclusively allocated to irrigation and

swimming pool consumption (Mayer et al., 1999). However, as far as the literature

goes, no study has analysed the influence of patios and verandas towards outdoor water

consumption. In Brazil, it is a common practice to wash patio and veranda floors

periodically and therefore, these outdoor spaces should be taken into consideration

during domestic water consumption analysis.

Another aspect of domestic water consumption to be taken into consideration is the fact

that water demand might be linked to built area, since the greater the floor area, the

higher the number of residents and water-using equipment (Memon and Butler, 2006).

According to Troy and Randolph (2005) the presence of water-using equipment can

influence the way water is used should be considered when studying behavioural

patterns of domestic water consumption. Rajala and Katko (2004) point out that

although domestic water consumption does not vary much according to built age of a

dwelling, the age of the water-using equipment has a more influential factor for

domestic water consumption.

2.3.5 Climate

Domestic water consumption can be divided into seasonal and non-seasonal uses. The

first is related with activities such as irrigation and cooling, which are weather

correlated. The latter, is related with water-consuming activities that are not weather

correlated, such as toilet flushing and dishwashing.

Seasonal water uses are commonly associated with outdoor water consumption and non-

seasonal water uses with indoor water consumption. Although this assumption might be

considered imprecise because some indoor water-consuming activities such as


26

evaporative cooling can be seasonal and some outdoor uses such as car washing can be

non-seasonal, it has been reported the major portion of seasonal water use within the

residential sector is attributed to irrigation (Dziegielewski et al., 1993).

Precipitation regimes usually affect outdoor water consumption for garden irrigation.

Sources of water required to maintain garden plants generally comes from a

combination of rainfall and supplementary irrigation water during dry spells (Foster and

Beattie, 1979). Consequently, the lack of precipitation induces consumers to apply

supplementary water in or to meet the requirements to maintain garden vegetation.

Evapotranspiration is related to the water loss from soil surface and plant transpiration.

It has been reported that net evapotranspiration can be used to measure outdoor water

use for garden irrigation (Mayer et al., 1999). The basic premise is that as

evapotranspiration raises, outdoor water demand for irrigation increases; however, as

humidity rises, outdoor water demand for irrigation decreases.

Although several water demand models have included different climatic parameters

such as temperature, precipitation and evapotranspiration (i.e. Billings, 1982; Hoffmann

et al., 2006; Mayer et al., 1999; Niewswiadomy and Molina, 1989), none of them seem

to have addressed relative humidity as a factor for outdoor water consumption for

garden irrigation.

Relative humidity is a measure of the amount of water vapour in the air and has a direct

relationship with precipitation and solar radiation. Relative humidity not only indicates

the likelihood of precipitation, but also is necessary for cloud formation. Therefore, low

levels of humidity implies in higher solar radiation, as clouds tend to decrease solar

intensity. Low relative humidity associated with high solar gain leads to high levels of

evapotranspiration, therefore increasing outdoor water demand for irrigation.

2.3.6 Behaviour and perception

Corral-Verdugo et al. (2002) argues that human behaviour is the major cause of

environmental deterioration, and that there is no evidence of a change in human

tendency to deplete natural resources. Occupant behaviour is perhaps the most


27

influential factor of domestic water consumption, and according to Jorgensen et al.

(2009), the success of domestic water conservation is dependent on the understanding of

how water is used and perceived by residents.

According to Gregory and Di Leo (2003), domestic water consumption behaviour is a

product of situational influences (i.e. household income, household size, dwelling

characteristics, and climate), unreasoned influences (i.e. habits and routines), reasoned

influences (i.e. attitudes, intentions and involvement) and stimuli (i.e. factual

information, knowledge and environmental awareness).

2.3.6.1 Situational influences

Situational determinants such as cost of water, household income, household size,

dwelling characteristics and climate, have been discussed above as variables that affect

domestic water consumption and therefore suggest a relationship with water

consumption behaviour.

According to Dziegielewski et al. (1993) income measures the ability of residents to

pay for water, whereas the cost of water influences the amount of water residents are

willing to purchase. Both variables are capable of affecting domestic water consumption

behaviour. On one hand, low income linked with high water costs might cause residents

to modify their behaviour by reducing water irrigation, number of laundry loads, taking

shorter showers, making use of alternative water supplies, etc. On the other hand, high

income linked with low water costs might lead to a water-spending behaviour.

As previously discussed, domestic water consumption is inversely related to household

size; therefore, the greater the number of residents in a household, the lower the per

capita water consumption. According to Arbués et al. (2010), such scaling economy is

associated with common household uses such as clothes washing. Households with a

higher number of family members have a greater need to form a conservationist

behaviour such as saving clothes to form full loads, using economy settings and avoid

unnecessary rinse cycles (Gregory and Di Leo, 2003).


28

Randolph and Troy (2008) explore variables of dwelling characteristics in Australia as

means to evaluate occupant behaviour towards domestic water consumption. According

to the authors, the ability to use water is dependent upon the range of water-using

facilities available in different residential building typologies. The number of water-

using facilities helps to explain how residents use their water and explain the differences

in water consumption behaviour. For example, flat dwellings tend to have a smaller

built area with fewer bathrooms, no gardens and swimming pools when compared to

house dwellings, thus limiting their potential to consume water, and therefore affecting

their behaviour towards domestic water consumption.

Climatic factors can also influence domestic water consumption behaviour. High

temperatures can lead to changes in behaviour for cooling by increasing the frequency

of showers. Also, low levels of precipitation affect garden plants, and to maintain the

garden, occupant behaviour changes in order to provide supplement water for non-

native vegetation.

2.3.6.2 Unreasoned influences

Unreasoned influences are associated with habitual “mindless” patterns of behaviour

that occur automatically. According to Aarts et al. (1998) behaviour is frequently

exhibited in the same physical and social environment and usually acquires a habitual

character. Such habitual behaviour proceeds in an efficient, effortless and unconscious

manner performed on a regular basis.

Domestic water consumption habits such as brushing teeth, shaving, bathing, washing

clothes, dishes and watering lawn are repetitive and frequent. According to Gregory and

Di Leo (2003), such habits tend to reduce cognition and it can either reflect routine, or it

can represent important constancies which are deliberate and intentional in nature.

Aarts et al. (1998) points out that habits tend to be goal-directed and are automatically

triggered by a certain stimuli. Also, the author argues that “satisfactory experiences

enhance the tendency to repeat the same course of action because the instrumental

action becomes more strongly associated with the goal one initially wished to attain”


29

(p.1358). For example, dry turf grass can trigger a habitual behaviour for periodic

irrigation in order to maintain the satisfactory experience of having a green garden.

2.3.6.3 Reasoned influences

Based on cognitive processes, reasoned influences can be associated with intentional

behavioural attitudes and personal involvement. According to Fishbein and Ajzen’s

(1975) theory of reasoned action, behaviour intentions are measured according people’s

attitudes towards expected outcomes and by their subjective norms.

Fishbein and Ajzen (1975) define attitude as a learned predisposition to respond to a

given stimulus, and although Gregory and Di Leo (2003) point out that attitude is an

important link between stimulus and response to water consumption, the authors claim

that the level of personal involvement is another factor that can affect daily activities of

water usage. For example, if residents become aware of a security of supply issue, the

need to conserve water becomes personally relevant, and they might take actions to

conserve water in the household.

2.3.6.4 Awareness stimuli

Stimuli are external influences that can trigger effects upon human behaviour. Stimulus

such as environmental awareness can trigger conscious pro-environmental water

consumption behaviours in a household. Awareness is the ability to be conscious of

determined objects, situation or action, through the processing of informational cues.

It has been reported that environmental knowledge is found to be consistently and

positively related to pro-environmental attitudes (Arcury, 1990; Arcury and Johnson,

1987). Therefore, environmental knowledge regarding human impacts on natural water

resources can lead to reasoned influences over domestic water consumption behaviour,

and attempts to change unreasoned influences might be carried out in order to save

water and reduce domestic water consumption.

According to Gregory and Di Leo (2003), awareness can be seen as the application of

knowledge to a specific situation. Situational influences such as water efficient fixtures,

appliances and water reuse systems at home, can affect the way water is used, and


30

therefore the lack of knowledge of such water-saving technologies could pose a

limitation to conscious actions (behavioural intentions) to saving water.

2.4 Domestic water end-use consumption

Domestic water consumption is defined by a sum of water-using activities originating

from different water fixtures and appliances inside and outside the home. According to

Memon and Butler (2006), these activities can be divided into two main categories:

personal and communal water usage. Personal water usage includes activities related to

hygiene (such as taking a bath, brushing teeth, washing face, using the toilet, etc.) and

communal water uses can be related to activities such as washing clothes, cooking, dish

washing, watering the lawn, etc.

Such water-using activities take place within determined spaces of the home, where

sources of water can be obtained from water fixtures and appliances. Mayer et al. (1999,

p.1) defines the end-uses of water as “all the places where water is used...”, including

toilets, showers, faucets, washing machines, etc. This study considers the term

‘domestic water end-use consumption’ as the amount of water consumed per fixture or

appliance inside and outside a household.

It is agreed amongst researchers that a clear understanding of domestic water end-use

consumption patterns make way to both demand predictions and to the development and

evaluation of water conservation measures (White and Fane, 2002). According to

Hobson et al. (2004) the study of domestic water end-use consumption is crucial to

achieve a more accurate forecast of water demand. The understanding of how much

water is consumed and where it is being put to use in the home is crucial to the design

and evaluation of water conservation programs (De Oreo et al., 1996). Furthermore, a

clear understanding of domestic water end-use consumption can help identify optimal

water conservation measures for an improved efficiency and effective water demand

management (Memon and Butler, 2006).

Numerous studies have characterized domestic water end-use consumption. Table 2.2

compares the results of domestic water end-use consumption data between different


31

countries in the world. Domestic water end-use values refer to the percentage of the

total domestic water consumption per person per day.

While some of the studies reported their findings according to the activities related to

domestic water consumption (i.e. bathing, shaving, drinking, cooking, clothes washing,

etc.), others focused their results according to water-using components of dwellings (i.e.

bath tubs, wash closets, washing machines, kitchen sink, etc.). Furthermore, while some

studies disaggregated water consumption values as much as possible, other studies

aggregated results using different terms to represent water uses in the home. For

example, some studies aggregated their water consumption data from wash basins with

that of kitchen sinks (internal faucets), while others aggregated such results with

showers and baths (personal hygiene).


32

Table 2.2 Comparison of domestic water end-use data from different studies in the world (% of total consumption).

Developed Countries Developing Countries

GB GB GB GB PT NL DK FI DE AT US US AU AU NZ BR BR BR BR CN TH LK

Thac

kray

et

al.

(1

97

8)

Hal

l et

al.

(1

98

8)

Bal

l et

al.

(2

00

3)

Ofw

at (

20

07

)

Vie

ira

et

al.

(2

00

7)

Geu

den

s (2

00

8)

Seth

(n

.d.)

,

as c

ited

in E

A (

20

08

c)

Etel

ämäk

i (1

99

9),

as

cite

d in

EA

(2

00

8c)

Um

wel

tbu

nd

esam

t (2

00

7),

as c

ited

in E

A (

20

08

c)

BM

LFU

W (

20

06

),

as c

ited

in E

A (

20

08

c)

DeO

reo

et

al.

(1

99

6)

May

er e

t a

l. (

19

99

)

Loh

an

d C

ogh

lan

(2

00

3)

Ro

ber

ts (

20

05

)

Hei

nri

ch (

20

07

)

Ro

cha

et

al.

(1

99

8)

Gh

isi a

nd

Fer

reir

a (2

00

7)

Gh

isi a

nd

Oliv

eira

(2

00

7)

Bar

reto

(2

00

8)

Zhan

g an

d B

row

n(2

00

5)

Ota

ki e

t a

l. (

20

08

)

Siva

kum

aran

an

d A

ram

aki

(20

10

)

Sample Size (No. of Dwellings) 853 1863 250 N.A. 43 N.A. N.A. N.A. N.A. N.A. 16 1188 1017 93 12 1 49 2 7 806 63 9

Indoor Use (Indoor Taps) 35 --- 23 --- 29 --- --- --- --- --- 16 --- 18 12 14 --- --- --- --- --- --- --- Personal Hygiene (Shower & Bath) --- --- --- 22 36 --- 37 49 36 41 --- --- 33 --- --- --- --- --- --- --- --- --- Wash Basin (Bathroom Faucet) --- --- --- --- --- 4 --- --- --- --- --- 16 --- --- --- 8 11 4 4 13 --- 5 Shower 1 2 8 --- --- 39 --- --- --- --- 17 17 --- 22 27 55 16 38 14 14 --- --- Bath 15 13 16 --- --- 2 --- --- --- --- 1.7 2 --- 2 3 --- --- --- --- 14 25 27 Toilet Flushing 32 29 30 34 21 29 23 14 32 22 25 27 19 13 19 6 33 27 6 14 19 14 Kitchen Sink --- --- --- 42 --- 6 17 20 9 9 --- --- --- --- --- 18 34 24 12 --- 19 19 Waste Disposal Unit 0.3 2 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Dishwasher 0.3 2 2 --- 3 2 --- --- --- --- 3 1 --- 1 1 --- --- --- --- 17 --- --- Clothes Washing (Utility Faucet) 3 --- --- --- --- 1 --- --- --- --- --- --- --- --- --- 3 2 --- 5 --- 23 15 Washing Machine 9 11 14 --- 11 12 19 14 14 17 24 22 27 19 24 11 2 7 28 14 --- ---

Outdoor Use (External Taps) --- 3 4 2 --- --- 4 --- 9 --- --- --- --- 25 8 --- --- --- --- --- --- --- Garden Irrigation 3 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 7 Car Washing 0.4 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 14 Swimming Pool --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---

Leaks and Losses --- --- 2 --- --- --- --- --- --- --- 12 14 --- 6 4 --- --- --- --- --- --- --- Other --- 39 2 --- --- 4 --- 3 --- 11 --- 2 3 --- 0.4 --- --- --- 31 14 --- ---

Per Capita Consumption (l/p/d) 98 130 N.A. 150 134 128 131 115 115 135 225 262 161 178 147 109 179 175 263 113 77 118


33

In order to clearly present results and to avoid confusion surrounding domestic water

end-uses, this research has presented disaggregated results according to water fixtures

and fittings inside and outside the home. This way, water-using activities can be

analysed and if necessary aggregated, according to fixture or appliance. Water fixtures

and appliances exist in the home for a determined use, and since water-using activities

originate from these sources, it made sense to categorize domestic water consumption

according to fixture and appliance. Furthermore, if domestic water end-use consumption

data is to be used for demand predictions to evaluate water conservation measures such

as water efficient fittings, fixtures and appliances and water reuse systems, it makes

sense to present water end-use consumption data at a disaggregated level of water

fixture and appliance.

Although studies reported their results in a different manner, it was possible to compare

their findings by aggregating domestic water end-use consumption at its simplest form:

(i) potable uses (internal faucets, personal hygiene, wash basin, shower, bath, kitchen

sink and dishwasher), (ii) laundry (washing clothes and washing machine), (iii) toilet

flushing and (iv) outdoor uses (car washing, garden irrigation and swimming pool).

‘Other’ end-uses were not included for comparison, as well as leaks, since not every

study reported water loss or had unaccounted end-uses in their homes.

Overall, average results from previous studies indicate that most of the water used in the

analysed homes was for potable uses (51%), followed by toilet flushing (21%), laundry

(17%) and outdoor uses (11%).

Evidently, a diversity of domestic water end-use consumption patterns between the

different studies in Table 2.2 can be found. According to Vieira et al. (2007, p.193),

domestic water usage can significantly vary from “country to country, region to region

and even from one residence to another...” , hence the importance of obtaining specific

information on how water consumption is affected by a series of independent variables

(as seen in the previous section).

Although a diversity of domestic water end-use consumption patterns between the

different studies can be found, the average values of potable and laundry are similar in

developed and developing countries; toilet flushing and outdoor water uses, however,


34

are different (Figure 2.12). Developed countries present a greater consumption trend for

toilet flushing, while developing countries contained a higher proportion for outdoor

uses. Overall, results obtained from this research (see Chapter 5, Section 5.4.5,Figure

5.18), presented similar proportions to those of developing countries, varying slightly in

laundry uses.

Figure 2.12 Average domestic water end-use consumption results of previous research.

Results of outdoor water uses from previous studies carried out in developed countries

were mainly accounted for in garden irrigation and car washing. Only two studies

carried out in Australia presented results for water consumption in swimming pools

(Loh and Coghlan, 2003; Roberts, 2005).

It is crucial to point out the fact that from the reviewed literature on water end-use

studies carried out in developing nations, only Sivakumaran and Aramaki (2010)

measured outdoor water usage for nine dwellings.

As far as the literature goes, this research represents the first attempt to understand

outdoor water uses in Brazilian dwellings (see Chapter 5, Section 5.4.5), since no

domestic water end-use study in Brazil has evaluated outdoor water end-use

consumption.

Potable Uses51%

Laundry15%

Toilet Flushing

26%

Outdoor Uses8%

Potable Uses51%

Laundry16%

Toilet Flushing

17%

Outdoor Uses16%

Developed Countries Developing Countries


35

2.4.1 Building typology

Although the great majority of the domestic water end-use studies carried out in

developed countries collected data solely for house dwellings, a few studies collected

domestic water end-use consumption data for both house and flat dwellings.

Although Thackray et al. (1978) demonstrated the average domestic water consumption

per capita according to building typology (detached, semi-detached, terraced, bungalow

and flat/maisonette), domestic water end-use consumption data was represented

according to sampled sites (Malvern and Mansfield).

Loh and Coghlan (2003) on the other hand, compared domestic water end-use

consumption according to houses and multi-storey flat dwellings. Results from their

study indicated that even though there were no significant variations between indoor

water end-use consumption between both dwelling typologies, house dwellings

contained outdoor water consumption 45% greater than multi-storey flat dwellings (as

seen in Figure 2.13).

In developing countries, water end-use studies were either focused in house dwellings

(Ghisi and Oliveira, 2007; Otaki et al., 2008; Sivakumaran and Aramaki, 2010), or flat

dwellings (Barreto, 2008; Ghisi and Ferreira, 2007; Rocha et al., 1998; Zhang and

Brown, 2005). This research, on the other hand, has evaluated domestic water end-use

consumption for both dwelling typologies in the Federal District (see Chapter 5).

2.4.2 Household income

From the reviewed literature, very little research has been carried out regarding the

socio-economic aspects of domestic water end-use consumption.

An early study in the United Kingdom, compared the average domestic water

consumption per capita according to different social groups in the cities of Malvern and

Mansfield (Thackray et al., 1978). Although income data was not included, the authors

evaluated domestic water consumption according to social grade classifications from the

20th century (professional, managerial, clerical, skilled and unskilled social groups).

Since such social grade classifications were indicators of household income, the average


36

values of domestic water consumption per capita, gathered from their findings in

Malvern and Mansfield, were plotted out in a graph to verify the differences in water

consumption according to such social groups (Figure 2.13). There were clear indications

regarding a direct relationship between social group and domestic water consumption in

the United Kingdom.

Figure 2.13 Per capita water consumption and social groups in the United Kingdom

Source: Thackray et al. (1978)

Figure 2.14 Monthly water consumption per income range in China

Source: Zhang and Brown (2005)

In developing countries, Zhang and Brown (2005) compared average monthly indoor

water consumption with different income levels of residential flat dwellings for the

0

20

40

60

80

100

120

140

160

Professional Managerial Clerical Skilled Unskilled Unclassified

Do

me

stic

Wa

ter

Co

nsu

mp

tio

n

(lit

res/

per

son

/day

)

Social Group

0

2

4

6

8

10

12

14

16

0 - 10,000 11,000 - 30,000 31,000 - 40,000 41,000 - 50,000 > 50,000

Do

me

stic

Wa

ter

Co

nsu

mp

tio

n(m

3 /d

wel

ling/

mo

nth

)

Income Range (RMB/dwelling/month)


37

cities of Beijing and Tianjin, China. The authors reported that a higher household

income results in a higher level of domestic water use and consumption. The average

values of monthly water consumption per dwelling and dwelling income range obtained

from the authors’ findings in Beijing and Tianjin were plotted out in a graph (Figure

2.14). Overall, Zhang and Brown’s results indicated that the constant increase in

monthly water consumption per dwelling was somewhat proportional to the increase in

household income range.

Loh and Coghlan (2003) on the other hand, provided a more in-depth analysis by

comparing average monthly and daily water consumption for high, middle and low

income dwellings in Perth, Australia. Their findings suggest that household income had

a significant effect upon outdoor water usage.

Figure 2.15 Average monthly water consumption by dwelling type and income range in Australia

Source: Loh and Coghlan (2003)

Figure 2.15 illustrates Loh and Coghlan’s findings. Noticeably, there was very little

variance of average domestic water consumption between high, middle and low income

dwellings from April-99 to October-99, however, significant changes in water

consumption between the different income ranges could be observed during dry spells,

from October-99 to May-00. The authors reported a decrease in outdoor water usage in


38

January-00, due to unseasonal rainfall. Noticeably, changes in water consumption were

proportional to income range; furthermore, these changes were equally distributed

throughout the summer.

The authors found a relationship between outdoor water consumption and the use of

automatic irrigation systems, comparing outdoor water consumption of dwellings with

automatic irrigation systems and dwellings without automatic irrigation systems.

However, no correlations with dwelling characteristics such as garden size and

swimming pool volume were made.

Furthermore, no domestic water end-use consumption data for the low, middle and high

income ranges were presented for analysis. This study on the other hand, has filled this

gap in knowledge by comparing domestic water end-use consumption between the

different income ranges in the Federal District (see Chapter 5).

2.5 Water end-use frequencies and activities

As previously seen in Section 2.3.6, unreasoned influences of domestic water

consumption is commonly associated with resident’s habits and routines. Previous

research suggest that one way of understanding the behavioural patterns of domestic

water usage is through the comprehension of the activities related to water consumption,

how equipments are used and the frequency of usage.

2.5.1 Frequencies of water usage

Although a few studies have evaluated water-using frequencies mostly as a basis for

water demand predictions (Ghisi and Ferreira, 2007; Ghisi and Oliveira, 2007; Heinrich,

2007; Mayer et al., 1999; Roberts, 2005; Vieira et al., 2007), they provide some

valuable information regarding the daily habits of residents. The frequency of appliance

and fixture use is directly linked to occupant behaviour, for example, the number of

times the average resident flushes the toilet in one day, the duration of a shower, how

often a load of clothes is washed, etc.

Table 2.3 on the next page shows indoor water end-use frequencies obtained by the

studies above in a comparable format. According to Mayer et al. (1999), frequencies of


39

appliances such as toilets, washing machines and dishwashers are best evaluated

according to the number of uses per day. Furthermore, the author argues that it is more

instructive to examine tap-opening fixtures according to the duration of usage per day.

Having this in mind, data from previous studies were used to obtain comparable

frequency rates according to number of uses (toilet flushing, washing machine and

dishwasher) and duration of usage (tap-opening fixtures) per person per day.

Table 2.3 Comparison of indoor water end-use frequencies of previous studies

Developed Country Developing Countries

New Zealand USA Australia Portugal Brazil Brazil

Heinrich (2007)

Mayer et al. (1999)

Roberts (2005)

Vieira et al. (2007)

Ghisi and Ferreira (2006)

Ghisi and Oliveira (2007)

Indoor Faucets 6 min/p/d 8.1 min/p/d 8.0 min/p/d --- --- --- Bathroom Faucet --- --- --- 0.8 min/p/d 1.3 min/p/d 4.0 min/p/d Shower 7.8 min/p/d 8.2 min/p/d 5.1 min/p/d 5.7 min/p/d 11.8 min/p/d 8.6 min/p/d Bath Faucet --- --- --- 6.7 min/p/d --- --- Toilet Flushing 5 f/p/d 5 f/p/d 4 f/p/d 9 f/p/d 4 f/p/d 6 f/p/d Kitchen Sink --- --- --- 1.5 min/p/d 2.3 min/p/d 1.6 min/p/d Dishwasher --- 0.1 load/p/d 0.2 load/p/d 0.5 load/p/d --- --- Utility Faucet --- --- --- --- 1.9 min/p/d --- Washing Machine 0.3 load/p/d 0.4 load/p/d 0.3 load/p/d 0.6 load/p/d 0.1 load/p/d 0.1 load/p/d

In order to compare results, wash basin, bath, kitchen and utility faucet frequencies were

aggregated according to indoor faucet use. Previous studies indicate that, in average,

frequency rates for indoor faucets run for 7.3 minutes per person per day (min/p/d).

Furthermore, results from previous studies indicate that the average duration of a

shower is equivalent to 6.7 min/p/d, toilets are flushed at a frequency of 6 flushes per

person per day (f/p/d), dishwashers are used in an average rate of 0.3 load per person

per day (load/p/d) and washing machines are used to wash clothes at a rate of 0.3

load/p/d. Only one study in Brazil presented results for the frequency of usage in utility

faucets (1.9 min/p/d).

Clearly, disaggregated results from previous studies varied significantly, however some

assumptions regarding water use frequency between developed countries and Brazil

could be made. Overall, developed countries presented higher average frequency rates

than Brazil. In average, the duration of indoor faucet usage in developed countries (7.3

min/p/d) was almost twice as high as in Brazil (4.6 min/p/d). Previous findings suggest

that while the average resident in developed countries uses the toilets six times a day at


40

home, the average resident in Brazil, flushes the toilet in average five times a day.

Previous studies also suggest that Brazilian households wash fewer clothes with the

washing machine (0.1 load/p/day) than developed countries (0.4 load/p/day). One

reason for this might be explained through the use of the utility sinks to wash part of the

laundry (1.9 min/p/d).

2.5.2 Water-consuming activities

Although frequency of water usage provides data regarding the number of uses of water

appliances and the duration of tap-opening fixture events, they fail to provide

information regarding the activities related to water consumption. Even though previous

research have focused in evaluating water-using frequencies, Randolph and Troy

(2008) has set out to understand the activities which lie behind domestic water

consumption in Australia, through an evaluation of key water using facilities inside and

outside the home. The authors argue that understanding the different approaches of

water-using behaviour is very important, especially when attempting to encourage

households to reduce water consumption, and in trying to understand the attitudes being

taken by residents in order to promote water conservation in their home.

In their study, Randolph and Troy (2008) report that most residents in Australia washed

their dishes by hand daily, using a plugged sink to rinse their dishes. Three quarters of

the respondents rinsed their dishes before, during or after washing. Although

approximately half of the dwellings sampled possessed a dishwasher, only 10% of those

who had a dishwasher never used it. This survey in Australia found that on average,

residents washed their clothes around four times a week. Although a small portion of

residents washed their clothes by hands, almost every household used a washing

machine at home using economy settings on the machine. According to Randolph and

Troy (2008), about half of the respondents washed their cars at home using a bucket.

From those who washed their cars at home, said they only did so every six months or

less. Furthermore, the study indicated that most of the interviewed properties with a

lawn never watered it. Dwellings with garden beds, however, were more likely to water

their plants once or twice a week.


41

As seen in Section 2.3.6, water consumption behaviour can be affected by

environmental knowledge or other external influences. In their research, Randolph and

Troy (2008) report that water restrictions had clearly prompted some changes in the way

water was used in Australian homes. Amongst different water-saving attitudes, their

findings indicated that the most common action taken to promote water conservation

was to reduce garden watering, take shorter showers and reduce car washing. The most

popular water-saving actions to be taken by residents were to control the bathroom

faucet while brushing teeth, fill the washing machine with clothes before use and use

economy settings. The authors report that a lack of interest to reuse water in the homes

was mostly related to high costs and impracticality.

2.6 Conclusion

This chapter has reviewed the literature regarding water demand and supply in a global,

country and regional scale, evaluating the Federal District’s fresh water availability and

water demand predictions. Clearly, water stress levels have been reached due to

population growth linked with a constant raise in per capita water consumption, and

because of this, new freshwater resources have to be drawn from far away. It is evident

that water resource management in the Federal District is being solely focused in an

engineering supply-side approach, feeding consumption as necessary, exacerbating local

resources, rather than controlling it through sustainable water demand management

programs.

In order to achieve a sustainable water demand management through water conservation

measures, it is crucial to understand what lies behind water consumption. This chapter

has reviewed the main drivers of domestic water consumption, such as the cost of water,

income, household size, dwelling characteristics, climate and even occupant behaviour.

It is evident that a clear understanding of the amount of water consumed per fixture or

appliance inside and outside a household is crucial to accurately predict domestic water

demand and evaluate the effectiveness of water conservation measures. Overall,

previous research indicates that domestic water end-use consumption can vary

according to building typology and household income. Furthermore, results from

previous studies suggest that water end-use frequencies within developed countries

might be higher than in developing countries.


42

Although numerous studies have characterized domestic water end-use consumption in

developed countries, little research has been carried out in developing nations. Variables

such as the cost of water, income, household size, dwelling characteristics, climate and

occupant behaviour can vary from place to place. In Brazil, research in domestic water

end-use consumption is still in its infancy. The literature indicates that no study has

evaluated outdoor water end-use consumption, nor compared the water end-use

consumption patterns between different income ranges and building typologies.

Furthermore, due to their limited sample size generalizable data has not yet been

produced. Clearly, there is a gap in knowledge towards the understanding of domestic

water end-use consumption for low, medium and high income households, for the

different residential building typologies and occupant behaviour within the Brazilian

context.

43

Chapter3 Domestic Water Conservation

Domestic Water Conservation

44

3. Domestic Water Conservation

3.1 Introduction

As seen in the previous chapter, the constant raise in per capita water consumption and

population growth is putting pressure upon the Federal District’s local water supplies,

and to feed this growing demand, new freshwater resources are being drawn from far

away. The concept of water demand management, which focuses in controlling water

consumption to postpone or avoid the need to develop new water supply systems

through educational, economic, regulatory and water conservation measures (Butler and

Memon, 2006), has been ignored by the Federal District government. Clearly, water

resource management in the Federal District is merely supply-driven, rather than being

integrated with a water demand management approach to sustain existing water supplies

and secure new freshwater resources for future generations.

According to Vickers (2001, p.5), water conservation measures include “specific tools

(technologies) and practices (behaviour changes)... that result in more efficient water

use...”. The author argues that water conservation technologies are generally more

reliable in achieving long-term water savings. With this in mind, this chapter reviews

the state of the art demand-side (water efficient strategies) and supply-side (water reuse

systems) water conservation technologies for residential buildings available in the

Brazilian market.

3.2 Water efficient strategies

Grant (2006, p.83) defines water efficiency as the ability of “doing more with less”.

Water efficient technologies are capable of reducing water consumption through the

improved effectiveness in the use of water, without any necessary changes in water-

consuming habits and routines. This section reviews the state-of-the-art water efficient

technologies available in the Brazilian market and provides water use data gathered

from manufacturers’ specifications for water efficient toilets, faucets, showerheads,

flow regulators, washing machines, washing equipments and irrigation systems.


45

3.2.1 Toilets

There are two basic types of toilets: (i) waterless toilets, and (ii) flush toilets. Waterless

toilets require no water for flushing and waste is commonly stored or treated on-site.

Flush toilets on the other hand, rely on water to discharge waste down the drainpipe,

and usually, transports it to another location for treatment.

3.2.1.1 Waterless toilets

According to Vickers (2001) waterless toilets include composting, incinerator, vacuum,

oil-flush and chemical toilet units. Composting toilets convert human waste into humus

and require a vented, drained chamber with adequate access for a periodic removal of

the compost (Grant et al., 2005). Composting toilets are not a suitable option within

urban areas, but can be an excellent solution for permaculture and remote sites without

reliable water supply or piped sanitary system (EA, 2007). Incinerator toilets use

electricity or butane to burn wastes, leaving an innocuous fine ash by-product, and are

commonly used in boats or remote locations where plumbed or composting toilets are

not practical (Vickers, 2001). Vacuum toilets use negative atmospheric pressure created

by a pumping station, to suck human waste into a sewage collection or treatment

chamber. Vacuum toilets are common in ships, trains and airplanes. In buildings,

however, such technology requires a vacuum sewage collection system and is mainly

applicable on sites with high water tables, unstable soil or restricted building conditions

(TIGRE, 2005). Oil recirculating toilets use mineral oil rather than water to flush the

toilet. Human wastes washed out by the oil medium, which is filtered and reused in the

toilet, are separated and contained in a holding tank for adequate disposal (EPA, 2000).

Oil-flush toilets are not widely used, but can be an option for remotely located, water

scarce areas. Chemical toilets are another way of storing human waste using chemicals

to disinfect and deodorize waste. Chemical toilets are portable toilets often used on

construction sites, outdoor gatherings and in caravans (Grant et al., 2005). Waterless

toilets are commonly used in public transports or remote sites with inadequate water

supply and piped sanitary system. Clearly, the use of waterless toilets in urban

residential homes is an unconventional practice. Therefore, this research has focused in

the use of water-flushing toilets for Brazilian dwellings.


46

3.2.1.2 Low-flush toilets

In Brazil, there are two types of flush toilets: (i) tank-style toilets and (ii) tankless

toilets. Tank-style toilets use a cistern to hold the correct amount of water required to

flush the toilet bowl. In case of low-flush toilets, a 6 litre cistern is used (i.e. Astra,

2009; Hervy, 2010; Roca, 2008). Tankless toilets are operated by a high pressure flush

valve which allows gravity-driven mains water from a loft water tank to flow directly

into the toilet bowl for flushing waste (Figure 3.1). Since they have no cistern, tankless

toilets have zero recharge time. Traditionally, high-pressure flush valves have been

associated with water wastage since they allow mains water to run freely while the flush

valve is being pressed (Schmidt, 2004).

Figure 3.1 Tankless high-pressure flush valve toilet.

Source: Adapted from (Docol, 2010b)

In recent years however, low-flow high pressure flush valves have been introduced into

the Brazilian market, limiting their flush volume to 6 litres, by allowing only a specific

amount of water to pass from the supply line into the toilet whilst the flush valve is

being pressed (Fabrimar, 2010; Hydra, 2007). It is crucial, however, to express the fact

that low-flush toilets require 6 litre per flush (lpf) toilet bowl designs in order to activate

the siphon effect for flushing waste. Results from a previous study carried out with


47

Brazilian toilets indicated that conventional 12 lpf toilet bowls, failed to discharge waste

using 6 litre flushing mechanisms (Santos et al. (1998) quoted by Junior (2002).

3.2.1.3 Dual flush toilets

Dual flush toilets use 6 lpf toilet bowl designs integrated with a flushing mechanism

which provides users the option of flushing toilets with 3 or 6 litres of water. Since

liquid waste require less water for discharge, a 3 litre flush volume can be used for a

minimal flush. Solid waste on the other hand, requires a full 6 litre flush in order to

completely remove the waste from the toilet bowl.

Figure 3.2 Dual flushing mechanisms for tank-style toilets (a) and tankless toilets (b)

(a) Cistern dual flush mechanism (b) Wall-mounted dual flush valve

Sources: Deca (2003) and Hydra (2007), respectively.

Two different types of dual flushing mechanisms can be found in the Brazilian market:

(i) cistern dual flush and (ii) dual flush high-pressure valves. Cistern dual flush

mechanisms are used on tank-style toilets and can be used as a retro-fitting device for

existing low-flush toilets with 6 litre cisterns and toilet bowls (Deca, 2003; Roca, 2008).

Dual flush high-pressure valves are used on tankless toilets and they can also be used as

retrofitting devices with low-volume toilet bowls (Docol, 2010a; Fabrimar, 2010;

Hydra, 2007).


48

3.2.2 Water faucets

Water faucet fixtures operate as valves to control the release and flow of water for

determined indoor and outdoor water-using activities (Schmidt, 2004). Water faucets

are commonly found in bathrooms, kitchens and utility rooms for indoor activities

related to personal hygiene, cooking, drinking and washing. Outdoor faucets, or external

taps, are generally used for garden irrigation and floor washing. Automatic faucets and

sensor faucets prevent water wastage and flooding where faucets can be left running

(EA, 2007). Although these fixtures are commonly used in public buildings, they can

also be applied to residential dwellings.

3.2.2.1 Automatic faucets

Automatic self-closing faucets use a hydro-mechanical valve to limit the flow of water

for a preset period (Deca, 2010; Docol, 2010a; Fabrimar, 2010). When the user presses

the button to deliver water flow, the faucet automatically closes after a delay period.

Generally, 7 second delay periods are often used, and according to Brazilian Standards

the operating time of automatic faucets should not be greater than 15 seconds (ABNT,

1996). When compared to standard faucets, automatic faucets use 20% less water

(SABESP, 1996).

Figure 3.3 Automatic bathroom faucet

Source: Docol (2010a)

Although automatic faucets are ideal for public washrooms, the Brazilian market has

recently introduced a new version for residential bathrooms (Docol, 2010a). Figure 3.3


49

shows an automatic bathroom faucet designed for residential purposes. A previous

study carried out in Brazil, installed automatic bathroom faucets in 13 low income

dwellings to evaluate their applicability (Vimieiro and Pádua, 2005). Results indicated

that, apart from one dwelling, most residents did not feel that the use of automatic

faucets in bathrooms was inconvenient to them. Hence, this study has included

automatic bathroom faucets for analysis.

3.2.2.2 Sensor faucets

Sensor faucets make use of an infrared sensor mechanism connected to a solenoid valve

that controls water flow (Gonçalves et al., 1999). The sensor is composed of an infrared

transmitter and a receiver. The transmitter emits a continuous infrared signal (a) and

once the presence of hands is detected by the receiver, the solenoid valve is activated,

releasing water for use (b). The solenoid valve terminates the flow of water (c), once the

hands are removed from the sensor range (Figure 3.4).

Figure 3.4 Sensor faucet operation

(a) (b) (c)

Source: Schmidt (2004)

Sensor faucets can be powered by a low voltage transformer or set of alkaline batteries.

Battery-driven sensor faucets avoid the need of an electrical source of mains electric

power supply, and can easily replace existing faucets. Some models are equipped with

both mains supply and set of batteries. In this case, the batteries act as auxiliary power

when there is a lack of mains supply (Gonçalves et al., 1999).

When compared to standard faucets, sensor faucets use up to 70% less water by

effectively reducing the time of water flow (Deca, 2010; Draco, 2010c). Although


50

sensor faucets are commonly applied to public bathrooms they can be easily applied to

domestic bathrooms. Furthermore, a new sensor faucet for kitchen use has emerged in

the market, containing an articulate spout with adequate distance and height for kitchen

sinks (Draco, 2010d).

3.2.3 Low-flow showerheads

Low-flow showerheads improve water use efficiency through the use of devices which

reduce water flow rates without losing effectiveness and the feeling of satisfaction by

users (figure 3.5). Low-flow shower heads can reduce water consumption by

modulating the flow rapidly or by aeration (Griggs and Burns, 2009).

Figure 3.5 Low-flow showerhead

Source: Fabrimar (2010)

Low-flow showerheads commonly contain an embedded flow regulator to reduce water

consumption. Some low-flow showerheads mix air with water to provide a larger spray

area to create a sensation of ample water, yet at reduced volumes (i.e. Draco, 2010a).

Other low-flow showerheads provide a narrower spray area without losing pressure to

the reduced flow rate (i.e. Fabrimar, 2010). Independent of the spray pattern, reduced

flow rates from showerheads can reach to a minimum 4.5 litres per minute (Draco,

2010a).


51

3.2.4 Flow regulators

Flow regulators are fittings capable of limiting the flow rate of faucets and

showerheads. In Brazil, flow regulators can be terminally-fitted in fixtures or wall

mounted (Figure 3.6).

Figure 3.6 Wall-mounted (a) and terminally-fitted (b) flow regulators

(a) (b)

Source: Fabrimar (2010)

Wall-mounted flow regulators are commonly installed at the feeding point of the water

supply pip (Docol, 2010a; Fabrimar, 2010). These devices act as a flow-restricting valve

providing a physical constriction that controls water flow. The water flow rate is

adjusted using a screw-driver. In multi-storey buildings, gradual adjustments according

to floor level can avoid extreme water pressure on lower floor levels and inadequate

water pressure on high floor levels. Furthermore, wall-mounted flow regulators can act

as an isolation valve, facilitating individual fixture repair and maintenance.

It is important however, to consider the fact that DIY adjustments are made ‘visually’

without obtaining precise water flow rates. Moreover, users could change efficient

settings to increased flow rates so that the water pressure ‘feels’ right. The use of

terminally-fitted flow regulators inside fixtures avoids these problems.

Overall, terminally-fitted flow regulators are a cheaper option and can be simply fitted

or screwed in faucets or showers. These devices can be purchased with different flow

rates and outlets. Commercially available flow rates for showers range from 3 to 18


52

litres per minute and faucets, from 1.8 to 7.5 litres per minute, depending on the type of

outlet used (Deca, 2010; Docol, 2010a; Draco, 2010b; Fabrimar, 2010). Faucet aeration

outlets (also known as aerators) reduce water flow rates by inserting air in the water as it

is being used. However, aeration outlets are only capable of aerating water above a

determined flow rate and pressure, spray outlets on the other hand, can function at much

lower flow rates (Griggs and Burns, 2009).

Although flow regulators are simple retrofit devices, it is crucial, to firstly measure

existing flow rates from fixtures to verify if the measured flow rate is not less than or

equal to the specified rates from flow regulators.

3.2.5 High-efficiency washing machines

In Brazil, the capacity of clothes washing machines ranges from 5kg to 15kg, and as a

general rule, the higher the capacity of the washing machine, the more water it uses

(Brastemp, 2008; Consul, 2010; Eletrolux, 2010b). Another factor which affects the

volume of water usage by washing machines is age. Older washing machines have a

tendency to use more water to wash clothes since the efficiency of washing machines

has been increasing in the last years (Vickers, 2001).

Figure 3.7 Operating design and relative water levels of top-load, vertical-axis washing

machines (a) and front-load, horizontal-axis washing machines (b).

(a) (b)

Source: Vickers (2001)


53

There are two main types of washing machines available in the Brazilian market: (i)

top-load and (ii) front-load models. Top-load washing machines contain a vertical-axis

tub to wash clothes using a central agitator to clean and rinse clothes (Figure 3.7a).

Front-load washing machines on the other hand contain horizontal-axis tubs to wash

clothes through a tumbling motion for cleaning and rinsing (Figure 3.7b). Due to their

operating design, front-load washing machines require lower levels of water than top-

load washing machines, hence, promoting a higher efficiency in water usage (Vickers,

2001). Although top-load washing machines are the most common model available in

the Brazilian market, some front-load washing machine models can be found (Eletrolux,

2010b; LG, 2010).

The type of washing programme and water level settings used for washing clothes can

have an influence over the amount of water used in a washing machine. In general,

different levels of water settings can be selected according to the amount of clothes to

be washed. While some recent models automatically set water levels according to the

quantity of clothes put inside the tub (Brastemp, 2008; LG, 2010), others contain water

level indications which allow the user to identify the most appropriate setting for the

amount of clothes to be washed (Consul, 2010; Eletrolux, 2010b). Although water usage

of standard washing machines can reach up to a maximum 300 litres per load

(Brastemp, 2008), high efficiency washing machines use a maximum of 74 litres per

load (Eletrolux, 2007).

Figure 3.8 Washing machine with programmed settings to facilitate grey water reuse

Source: Eletrolux (2010a)


54

Another recent feature added to Brazilian washing machines, are programmes which

promotes the reuse of grey water (Eletrolux, 2010a). Some people store grey water from

washing machines in buckets, butts or plugged utility basins for reuse (see Chapter 5,

Section 5.5.2 and Section 3.3.2 from this chapter), and to facilitate this activity, some

new washing machines contain a ‘water reuse’ programme that can pause the washing

operation allowing the user to place its flexible discharge hose at a bucket, butt or

plugged utility basin for later reuse (Figure 3.8).

3.2.6 Pressure washers

Pressure washers are mechanically-driven appliances that use high-pressure water to

clean and remove dirt from surfaces and objects (Figure 3.9). Pressure washers are

available in different powers and flow rates, ranging from domestic to commercial

purposes. Pressure washers for domestic applications, such as floor and vehicle

washing, produce a high-pressure stream of water ranging from 100 to 140 Bar with a

restricted water flow rate from 5.5 to 7.7 litres per minute (Black&Decker, 2008;

Karcher, 2010).

Figure 3.9 Domestic pressure washer

Source: Karcher (2010)

Pressure washers use air-assisted nozzle guns that control water flow and can be

adjusted from wide fan spray to single jet spray (Bosch, 2010). Furthermore, some


55

pressure washers are designed to include additional accessories and cleaning agents to

enhance performance and increase the effectiveness of the cleaning process, hence

reducing time and avoiding water wastage.

Generally, pressure washers are connected to mains water supply, and in order to

achieve water savings, it is crucial to use a pressure washer whose flow rate is lower

than those from external taps. Since pressure washers contain high-pressure water

pumps, they can also be connected to treated rainwater or grey water tanks or butts to

assist water reuse.

3.2.7 Automatic shut-off nozzles

In Brazil, hand-held hose pipes are typically used for floor washing, vehicle washing

and garden irrigation. Their misuse, however, can lead to high rates of water wastage.

Unattended hose pipes with running water during a water-consuming activity are

common scenes of water wastage in Brazilian dwellings. The use of automatic shut-off

nozzles in the end line of hose pipes, however, are capable of providing a more efficient

use of water, by controlling flow according to user operation (Vickers, 2001).

Figure 3.10 Automatic shut-off nozzle with multiple spray patterns

Source: Aquacraft (2008)

Some automatic shut-off nozzles are available in multiple spray patterns which allow

users to choose the most appropriate pattern to effectively direct water where is needed

(EA, 2007). An example of an automatic shut-off nozzle with multiple spray patterns is


56

shown in Figure 3.10. According to Vickers (2001), the use of automatic shut-off

nozzles are expected to save 5 to10% of water used in hose pipes.

3.2.8 Automatic irrigation systems

Garden areas can be irrigated manually, or through the use of automatic irrigation

systems. In Brazil, manual irrigation is usually done through the use of hand-held hose

pipes and portable sprinklers placed on the lawn. Hand-held hose pipes are commonly

used on small turf areas and plant beds, while sprinklers and perforated hoses are

generally applied to larger gardens.

Water efficient irrigation equipments and practices are capable of promoting water

reductions by ensuring that water is only applied when, and where it is needed (Vickers,

2001). Manually-driven irrigation can lead to an uncontrolled and ineffective usage of

water. Equipments such as hose pipes and sprinklers, can lead to significant water losses

if left unattended. According to Vickers (2001) soil becomes saturated after being

watered for 10 to 15 minutes and he argues that in order to irrigate hard-to-reach areas,

residents often place manually operated sprinklers in ways that the spray pattern

overlaps the irrigable area.

Automatic irrigation systems on the other hand, make use of devices to increase

effectiveness and promote water efficiency. According to QWC (2009), water efficient

irrigation systems contain a network of permanent piping connected to effective

watering devices installed to water specific plants or landscape area. Efficient sprinklers

with variable spray patterns and angles are commonly used for watering turf areas by

applying water uniformly across the garden and effectively watering hard-to-reach

areas, while soaker hoses can be used for drip-irrigation at the foot of trees, shrubs and

flowers (Bilderback and Powell, 1996).

Efficient irrigation also involves scheduling effective watering periods based on plant

needs. Flow control devices (Figure 3.11a) are capable of providing an automated

irrigation schedule according to specified duration and frequency settings. Soil moisture

sensors (Figure 3.11b) connected to flow control devices are capable of managing the


57

irrigation system according to soil moisture level, boosting efficiency and saving water

(Gardena, 2010).

Figure 3.11 Automatic flow control device (a) and soil moisture sensor (b)

(a) (b)

Source: Gardena (2010)

3.2.9 Water leakage repair

Water leakage reduces system efficiency, leads to water wastage and increases water

consumption and costs. Even slow continuous flows of water leakage can lead to

significant amounts of water loss if not fixed promptly (EA, 2007). Table 3.1 shows the

estimated water loss rates from common visible leaks at water fixtures and appliances

inside the home (Sautchuk et al., 2005).

Table 3.1 Estimated water loss from visible leaks

Water Fixture/Appliance Leakage Flow Rate Estimated Water Loss

Faucets and External Taps

Slow dripping leakage 6 to 10 litres/day

Medium dripping leakage 10 to 20 litres/day

Fast dripping leakage 20 to 32 litres/day

Fast-flow dripping leakage > 32 litres/day

2mm stream > 144 litres/day

4mm stream > 333 litres/day

Leakage at supply line 0.86 litres/day

Toilets

Visible leak (ripple effect in toilet bowl) 144 litres/day

Leakage at supply line 144 litres/day

Stuck high-pressure flush valve 1.6 litres per second

Showers Leakage at shower valve 0.86 litres/day

Leakage at supply line 0.86 litres/day Source: ANA et al. (2005, p.34)


58

Overall, visible leaks can be avoided through simple maintenance or easily repaired

through the replacement of worn parts. Water losses in toilets generally occur within the

flushing mechanism, and are commonly caused by worn or deteriorated valve fittings

and poorly sized replacement parts and adjustments (Vickers, 2001) . The author also

points out that faucet leak repairs and adjustments include the replacement of worn

washers, tightening of faucet stem or base and replacement of packing nut. Shower

leakage generally occur at their valves due to worn out washers or valve seat grinders,

however, leakage at showerhead connections should also be taken into consideration

(ANA et al., 2005).

Invisible leaks can occur within the mains water supply pipe, pipes inside walls or loft

header tanks (SABESP, 2010). Overall, invisible leaks are difficult to detect and to

estimate water loss. Invisible leakage repair within supply or distribution pipework

might require digging-up the ground or breaking walls in order to fix the problem.

Leakage repair at loft header tank can be done by regulating or replacing float valves.

3.3 Water reuse systems

Domestic water reuse systems are supply-driven water conservation measures which

make use of alternative sources of water for non-potable end-uses such as irrigation,

toilet flushing, floor, vehicle and clothes washing. Supply-side water conservation

measures are based on the concept of identifying alternative sources of water to

substitute the use of potable water in activities which do not require such high standards

of water quality (Alegre et al., 2004; Kim et al., 2007; Sakellari et al., 2005).

Alternative sources of water for domestic water reuse systems include rainwater, grey

water and wastewater (Diaper et al., 2001; Wilson and Navaro, 2008; Winward et al.,

2009). This section provides an overview of commercially available rainwater

harvesting (RWH), grey water recycling (GWR) and wastewater reclamation (WWR)

systems for non-potable domestic water reuse in residential buildings in Brazil.

According to Kim et al. (2007) the level of water quality for reclaimed water, should

correspond to its intended application. Brazilian water supply regulations NBR 5626

(ABNT, 1998) allows the use of reclaimed water for non-potable end-uses which are not

required to meet the potable standards established by the Ordinance no 518 of the


59

Ministry of Health in Brazil (Saúde, 2004). However, NBR 5626 requires that should be

no cross-connections between potable reclaimed water pipework and there is back-flow

protection to avoid mains water contamination.

In other words, the use of alternative sources of water in buildings implies ‘water

production’, and therefore, specific care must be taken in order to guarantee a minimum

standard of water quality. Although the installation of water reuse systems in residential

buildings in Brazil is not prohibited, the National Water Agency (ANA) provides

detailed water quality standards based on aesthetic, microbiological, chemical and

physical parameters regarding reclaimed water quality for non-potable end-uses. The

necessary water quality standard to be met depends on specific categories of non-

potable water end-uses (ANA et al., 2005):

• Reclaimed water for garden irrigation or floor washing

- Should be odourless;

- Should not contain components which might damage plants or promote

micro-organisms growth;

- Should not be abrasive or stain surfaces;

- Should be free of microbial infection or contamination harmful to human

health.

• Reclaimed water for vehicle washing


- Should not be abrasive or stain surfaces;

- Should be free of dissolved solids;


health.

• Reclaimed water for toilet flushing


- Should not be abrasive, stain surfaces or deteriorate water fittings and

fixtures;


health.

• Reclaimed water for clothes washing

- Should be colourless, odourless and free of turbidity;


60

- Should not be abrasive, stain surfaces, or deteriorate water fittings and

appliances;

- Should be free of dissolved solids, metals and algae;


health.

It should be noted, however, that this study focuses in the use of commercially available

water treatment units to avoid issues related with water quality and meet the standards

described above, according to the specified categories of domestic water end-uses.

Although water reuse systems come in different arrangements, overall, they contain

similar processes and components, based on (Leggett et al., 2001a) Sant’Ana and

Amorim (2007) provide a conceptual description of the composition of water reuse

systems installations within the Brazilian perspective (Figure 3.12).

Figure 3.12 Conceptual flow diagram of water reuse system composition

Source: Sant’Ana and Amorim (2007)

In general, a network of collection pipes is used to collect and deliver alternative

sources of water (such as rainwater, grey water or wastewater) to a collection tank or, in

some cases, directly to points of use (Leggett et al., 2001a).


61

The level of treatment, be it through biological, chemical or physical processes, varies

according to the initial quality of the reclaimed water and its desired final quality, to be

met according to specific categories of water reuse (Tchobanoglous et al., 2003).

After treatment, reclaimed water can then be stored inside a collection tank, whose

design generally includes a manhole for maintenance and cleaning, an overflow

mechanism for excess water as well as a backflow prevention device, and whose

dimensions are estimated according to reclaimed water supply and demand rates

(ABNT, 1994; ABNT, 2007).

Water pumps can be operated manually to transport reclaimed water directly to points

of use (i.e. irrigation, floor and vehicle washing), or they can be operated by level

switches to feed a non-potable water distribution header tank at building loft level for

gravity-fed indoor end-uses such as toilet flushing and clothes washing. Water pumps

should be adequately dimensioned to supply water according to the required header tank

height and they must be protected from dry running (ABNT, 1992).

Non-potable water distribution header tanks should be connected to mains water supply

in case of system malfunction or lack of adequate quantity of reclaimed water to meet

demand (Sant'Ana and Amorim, 2007). Figure 3.13 provides an example of potable and

non-potable water header tank configuration.

High and low level switches can be used to activate and deactivate the water pump to

supply reclaimed water to the non-potable water header tank. A solenoid valve controlled

by a level switch located inside the non-potable water header tank starts and stops the mains

top-up function, ensuring that a minimum amount of water is available to supply the non-

potable end-uses at all times.

To comply with Brazilian water supply regulations, the header tanks should be covered,

contain an overflow/warning pipe and a cleaning outlet (ABNT, 1998). Furthermore, an

air gap arrangement should be provided with an adequate distance between mains water

inlet and non-potable water feeding in order to prevent mains contamination. The air

gap must be greater than or equal to, two times the sum of the inlet pipe diameters.


62

Figure 3.13 Potable and non-potable water header tank configuration

Non-potable water distribution pipework should be installed as a separate water supply

system from mains water pipework and dimensioned according to demand (ABNT,

1998). Non-potable water pipework should be colour coded for identification and points

of non-potable water consumption should contain graphical signs fitted with the words

‘non-potable water’ (ABNT, 2007).

3.3.1 Rainwater harvesting systems

Rainwater harvesting (RWH) systems collect rain through an impervious surface and,

rather than allowing storm water to drain away, runoff is treated and stored for later use

(Fewkes, 2006). Harvesting rainwater is a simple concept that might promote self-

sufficiency, saves mains water and is capable of minimising erosion, sedimentation and

flooding caused by urban runoff (Woods-Ballard et al., 2007). Historically, the

collection, storage and reuse of rainwater has been employed by different civilisations

throughout the world (Gould and Nissen-Petersen, 1999) and has evolved drastically in

the past years to state-of-the-art, commercially available rainwater reuse products

(Herrmann and Schmida, 1999).

Previous works indicate that treated rainwater can be safely used for irrigation, toilet

flushing and washing (i.e. Fewkes, 1999; Jones and Hunt, 2010; Li et al., 2010;

Villarreal and Dixon, 2005), and if adequately sterilized, rainwater can even be used for

potable purposes (i.e. Amin and Han, 2009; Helmreich and Horn, 2009; Peter-Varbanets


63

et al., 2009). However, Brazilian water supply regulation NBR 5626 does not allow the

application of reclaimed water sources of water for potable end-uses (ABNT, 1998).

According to the norm (ABNT, 1998, p.8), “the supply of potable water should only be

carried out by the public mains water facility company”. Concessions for the use of

alternative sources of water for potable end-uses might be obtained for specific cases

where mains water is not supplied, as long as potable water standards are achieved and

controlled in accordance to the Ordinance no. 518 of the Ministry of Health, under the

responsibility of the public mains water facility company (Saúde, 2004).

Since this study deals with the urban setting of the Federal District, where mains water

supply is readily available, this research has focused on rainwater harvesting systems

for non-potable water end-uses.

3.3.1.1 Rainwater quality

Rainwater is relatively pure and low in contaminants. However, the water quality of

collected rainwater can be affected by atmospheric pollutants during precipitation and

by physical, chemical and microbiological contaminants during run-off (Evans et al.,

2006; Lye, 2009; Spinks et al., 2003). According to Leggett and Shaffer (2002), the

main contaminants of harvested rainwater include:

• bird droppings

• leaves and other organic matter

• dust and grit

• airborne chemical pollutants; these usually occur near to their source (e.g. local

industry) and, as such, should not represent an additional health threat

• where rainwater is collected from paved areas at ground level, it may be

contaminated by dirt, silt, plant debris, animal faeces

Previous studies indicate that the water quality of harvested rainwater is directly linked

to system design and material selection (Lye, 2009). Ward et al.(2010) outline the

importance of appropriate rainwater harvesting system design and material selection to

optimise the quality of harvested rainwater.


64

3.3.1.2 System components and design

The design and installation of rainwater harvesting systems in Brazil should comply

with the Brazilian rainwater reuse regulation NBR 15527 (ABNT, 2007) in order to

guarantee the safe reuse of harvested rainwater from roof areas in urban areas for non-

potable end-uses.

The simplest form of a rainwater harvesting system can be obtained by simply

connecting a water butt or tank to a downpipe for external end-uses of non-potable

water (Woods-Ballard et al., 2007). The extraction of the stored rainwater can be done

manually, or through the aid of a water pump. More complex RWH systems store larger

quantities of rainwater and supply water for use within buildings. Leggett et al. (2001a)

categorizes RWH systems according to the way rainwater is supplied to points of use:

(i) directly pumped, (ii) indirectly pumped and (iii) gravity fed systems.

Since mains water is indirectly fed to points of use through a loft header tank, indirectly

pumped rainwater harvesting systems has been considered as the more appropriate

design for Brazilian buildings. Figure 3.14 on the next page illustrates a generic

composition of an indirectly pumped RWH system (Sant'Ana and Amorim, 2007).

Although rainwater can be harvested from roofs and other surfaces around the

buildings, such as paved areas and car parks, ground catchment surfaces are more likely

to contain higher levels of pollutants such as oil and faecal material which can

significantly affect the quality of the harvested rainwater (EA, 2008b). Therefore, to

reduce the level of treatment required for reuse and avoid potential health hazards to

occupants, the Brazilian norm NBR 15527 has limited the collection of rainwater run-

off only from roof-tops (ABNT, 2007).

The volume of rainwater collected is estimated according to the product of the

horizontal plan area of the roof and local average rainfall data (Fewkes and Warm,

2000). However, not all of the rain falling on roof areas can be collected, as some of the

run-off is lost due to processes such as depression storage and evaporation (Gould and

Nissen-Petersen, 1999). Such losses are quantified using a run-off coefficient that

represents the portion of rainwater collected from the roof in comparison to an idealised

catchment from which no losses occur (Fewkes and Warm, 2000). In order to account


65

for losses during run-off, the effective volume of rainwater collected can be determined

by multiplying the run-off coefficient to the volume of rainwater collected. Leggett et

al. (2001a) provides run-off coefficients relative to roof types (Table 3.2).

Figure 3.14 Generic composition of a rainwater harvesting system

(a) Catchment Area (b) Collection Pipework (c) Filter (d) Rainwater Cistern (e) Calmed Inlet (f) Overflow (g) Suction Pipe with

Floating Filter (h) Water Pump (i) Distribution Pipework (j) Header Tank (k) Potable Water Feed (l) Solenoide Valve


Table 3.2 Run-off coefficients relative to roof types

Roof Type Run-off Coefficient

Pitched roof tiles 0.75 – 0.9

Flat roof smooth surface 0.5

Flat roof with gravel layer or thin turf 0.4 – 0.5 Source: Leggett et al. (2001)


66

During periods of dry spells, roofs become contaminated with accumulated pollutants

such as atmospheric particulates, bird droppings, leaves and other debris (EnHealth,

2004). When it rains, most of the accumulated pollutants are washed away during the

initial part of the rainfall event (Gardner et al., 2004). First flush devices divert this

initial stage of rainwater run-off, where pollutant concentration is considerably higher

than at a later period (Athanasiadis et al., 2010).

Although previous studies indicate that rainwater quality improves once pollutants are

flushed away (i.e. Gardner et al., 2004; Martinson and Thomas, 2005; Yaziz et al.,

1989), Gardner and Vieritz (2010, p. 123) argues that first flush devices “appear to do

little to improve the chemical and microbiological quality of the collected rainwater”.

According to Konig as cited in Fewkes (2006), first-flush diversions are unnecessary to

rainwater harvesting systems. They can, however, be regarded as an additional barrier to

reduce contamination of stored rainwater (EnHealth, 2004). But according to Mustow et

al. (1997), the inclusion of first flush devices can increase the costs and complexity of a

system without promoting any significant benefits.

Figure 3.15 Example of downpipe (a), subsurface (b) and floating (c) rainwater filters

(a) (b) (c)

Source: (WISY, 2010)

It is, however, recommended to filter rainwater before its entry into the storage tank to

remove debris such as leaves, grit, moss and soil, which can lead to degradation of

water quality (Woods-Ballard et al., 2007). Leggett et al. (2001) identifies a range of

filter types including screen, cross flow, cartridge, slow sand, rapid sand, membrane and

activated carbon filters. Figure 3.15 illustrates the commercially available rainwater

filters in Brazil, including downpipe filters (a), subsurface filters (b) and floating fine


67

filters (c) attached to the extraction hose pipe inside the rainwater cistern (3P-Technik,

2010; WISY, 2010).

The purpose of filtration is to remove impurities from the rainwater before its storage

and extraction. Commercially available self-cleaning rainwater filters are selected

according to their capacity to filter rainwater, which is estimated according to the roof

area used for rainwater collection (3P-Technik, 2010; WISY, 2010). During the process

of filtration, some rainwater is lost while removing debris to a soakaway or run-off

drain. To account for this loss, Leggett et al. (2001) suggests the application of a filter

coefficient for the calculation of the effective volume of rainwater collected. The filter

coefficient is determined according to the efficiency of the filter used. In average,

commercially available self-cleaning rainwater filters are 90% efficient, in other words,

they contain a filter coefficient of 0.9 (3P-Technik, 2010; WISY, 2010).

A rainwater collection tank (or cistern) is required to store rainwater because rainfall

events occur more erratically than demand (Fewkes, 2006). Rainwater cisterns can be

constructed from a variety of materials such as fibreglass, polypropylene, wood, metal,

concrete and fibrocement (TWDB, 2005). In Brazil, commercially available rainwater

cisterns can be found in 3, 5 and 10 m3 modular volumes, composed of high-density

polyethylene designed to be placed below the ground (Acqualimp, 2010; Fortlev,

2010). Apart from aesthetics and space-savings, the main advantage of installing

rainwater cisterns underground, is that it protects the tank from daylight and helps to

regulate the temperature of the water inside the tank, limiting algal and bacterial growth

(EA, 2008b).

According to Fewkes (2006), in addition to filtration, further treatment of the collected

rainwater occurs inside the rainwater cistern through sedimentation and floatation.

When filtered rainwater enters the collection tank, fine particulates can still be found in

the water. Particles which are denser than water settle to the bottom of the tank, where a

beneficial biofilm composed of aerobic bacteria can develop, adding an additional stage

of biological treatment. In order to avoid the disturbance of this sedimentation as

rainwater is fed inside the tank, a calmed inlet is used to maintain the quality of the

filtered rainwater. Particles that are less dense than water float to the surface, and


68

therefore, a floating suction pipe is used to extract rainwater at its cleanest point, just

below the surface. Floating filters connected to the suction pipe can also be used as a

fine mesh filter to improve water quality. The cistern should be designed to overflow at

least twice a year for the removal of these particles.

The performance of a rainwater harvesting system is related to the storage capacity of

the rainwater cistern and the balance between rainwater supply and demand. According

to Fewkes and Butler (2000), the storage capacity of the rainwater tank is important

both economically and operationally since the storage capacity will influence:

• the volume of mains water conserved;

• the installation costs of the system;

• the length of time rainwater is retained, which affects the final quality of the

water supplied;

• the frequency of system overflow, which affects the rate of removal of surface

pollutants;

• the volume of water overflowing into the surface water drain or soakaway.

Fewkes (2006, p.40) defines a rainwater cistern as “a reservoir, which receives

stochastic inflows (rainwater) over time and is sized to satisfy the demand on the

system”. Two main techniques for sizing reservoirs have been identified by McMahon

and Mein (1978): (i) Moran related methods and (ii) critical period methods.

Moran related methods are a development of Moran’s theory of reservoir storage, where

a system of simultaneous equations is used to relate reservoir capacity, demand and

supply, and the analysis is based upon queuing theory (Fewkes and Butler, 2000).

However, according to Fewkes (2006), by using this approach, solutions are only

possible for idealized conditions. Furthermore, this method has not been widely applied

to rainwater collectors. They are primarily used for predicting the probability of failure

of a reservoir with a given capacity (i.e. Ragab et al., 2001). This approach was

considered irrelevant, since it is not the intention of this study to assess the failure rates

from rainwater cisterns.


69

Critical period can be defined as a period during which a reservoir goes from a full

condition to an empty condition (McMahon and Mein, 1978). Critical period methods

determine storage capacity through the use of sequences of flows derived from historic

data, where demand exceeds supply (Fewkes and Butler, 2000). Fewkes (2006)

subdivides these methods into two categories: (i) mass curve and (ii) behavioural

analysis.

The mass curve method, developed by Rippl in 1883, involves the identification of an

ideal storage capacity based on the critical periods of the data using the maximum

cumulative difference of a variable inflow (rainwater supply) and a constant outflow

(demand). With regards to a rainwater harvesting system, a cistern will perform

adequately provided the relationship shown in Equation 3.1 is satisfied (Fewkes, 2006).

≥ � � � � �� − ��

�� (3.1)

C = Storage Capacity Qt = Demand during time interval, t St = Supply during time interval, t

Although mass curve is a simple method that identifies the ideal rainwater storage

volume, it is not possible to compute mains water savings for different storage volumes.

Behavioural analysis on the other hand, is capable of simulating the performance of a

number of storage capacities.

Behavioural analysis simulates the operation of a reservoir with time. Here, the changes

in storage content of a finite reservoir are calculated using Equation 3.2 (McMahon and

Mein, 1978).

0� = 0�12 + �� − �� − ∆5� − 6� (3.2)

Subject to 0 ≤ Vt-1 ≤ C Vt = Storage volume at time interval, t Vt-1 = Storage volume at time interval, t-1 St = Supply during time interval, t Qt = Demand during time interval, t ΔEt = Net evaporation loss during time interval, t Lt = Other losses during time interval, t �i.e. seepage C = Storage Capacity


70

However, commercially available rainwater cisterns in Brazil are essentially water tight

and designed to be used underground, protected from daylight. Therefore, net

evaporation loss (∆E), and other losses (L) such as seepage can both be ignored.

The volume of rainwater at the end of a determined time interval (Vt) is therefore equal

to the volume of rainwater from the previous interval (Vt-1) plus the additional rainwater

being supplied (St), minus the demand (Qt) from the time period. Provided, that is, the

computed volume in store does not exceed the storage capacity (C).

3.3.2 Grey water recycling systems

Eriksson et al. (2002), defines grey water as wastewater without any waste input from

toilets and bidets (black water). Some authors classify grey water as used washwater

from showers, baths, washbasins, washing machines, kitchen sinks and dishwashers (i.e.

Jefferson et al., 2000; Ottoson and Stenstrom, 2003; Pidou et al., 2008), while others

exclude grey water sources from kitchen sinks and dishwashers because they normally

contain high levels of contamination from detergents, fats and food waste (i.e. Al-

Jayyousi, 2003; Donner et al., 2010; Nolde, 2000).

Although there still seems to be no consensus towards what defines grey water (Gross et

al., 2007), Leggett and Shaffer (2002) argue that the majority of commercially available

grey water treatment units are not designed to include wastewater from kitchen sink or

dishwasher. Moreover, these authors state that the additional volume generated from

kitchen sinks and dishwashers is unlikely to justify the additional costs related to their

treatment. Therefore, this investigation has focused in grey water sources that do not

include wastewater from kitchen sinks and washing machines.

Treated grey water can be safely used for non-potable domestic water end-uses such as

irrigation, toilet flushing and washing (i.e. Christova-Boal et al., 1996; Kim et al., 2009;

Lu and Leung, 2003). Previous works also indicate that untreated grey water can be

safely used for direct reuse in sub-surface irrigation or manual bucketing (DHWA,

2002; EA, 2008a; NSW, 2008a; SA-Health, 2008). Intermediate storage without

treatment and disinfection is not recommended as grey water quality can deteriorate and

pose a potential hazard to human health.


71

3.3.2.1 Grey water quality

The water quality of grey water is dependent upon the types of contaminants it picks up

during water use (Leggett and Shaffer, 2002), and varies according to the number of

occupants, age distribution, lifestyle, health status and water usage patterns of the

household (DHWA, 2002). Overall, grey water contains a range of impurities such as

skin, hair, soaps and detergents used for washing and bathing, surface cleansers and

anything else that may be casually poured down the drain (Leggett et al., 2001a).

The most significant risk from untreated grey water is exposure from micro-organisms

derived from faecal contamination. Grey water from showers, baths and washbasins

might contain traces of human intestinal bacteria (i.e. urine, faeces, vomit, etc.) and

viruses. As such, reuse of untreated grey water should be carried out in a manner that

avoids human infection through ingestion or skin contact, and treated grey water should

follow the non-potable water quality standards established by the National Water

Authority (ANA) in Brazil.

To date, there are no specific norms for grey water recycling in Brazil, however,

Brazilian septic tank regulations NBR 13969 (ABNT, 1997), allows the reuse of treated

wastewater on non-potable end-uses such as irrigation, floor washing, car washing,

toilet flushing, etc.


Grey water recycling (GWR) systems collect the used wash water before it reaches the

sewer or septic tank system, and makes it available for reuse elsewhere, where the water

required does not have to be of potable quality (EA, 2000).

The simplest form of grey water reuse is through manual bucketing. Manual bucketing

has become a commonly used method of untreated grey water reuse for landscape

irrigation in Australia (Misra and Sivongxay, 2009). Recent Australian government

regulations and guidelines provide initiatives for grey water reuse, using particularly

laundry and bathroom grey water for garden irrigation (DHWA, 2002; NSW, 2008a;

SA-Health, 2008). The Australian government considers manual bucketing of grey

water to be a low risk activity for the following reasons (NSW, 2008a: p.22):


72

• Manual bucketing reuses low volumes of grey water. Accordingly, only low

quantities of contaminants will be applied to the soil and there is a limited ability

for runoff to neighbouring properties or waterways.

• It is unlikely that manual bucketing will occur during wet weather, reducing the

risk of over-watering or runoff.

In Brazil, manual bucketing of laundry grey water is a common practice in some

households. Although there is a lack of literature regarding manual bucketing of grey

water in Brazil, this study has shown that a considerable number of low and mid-low

income dwellings made use of laundry grey water stored in water butts, mainly for floor

washing (see Chapter 5, Section 5.5.2).

Grey water diversion systems use simple mechanisms to redirect untreated bathroom

and/or laundry grey water via a sub-surface irrigation distribution pipework. According

to NSW (2008a), diversion systems incorporate the following features:

• a hand-activated valve;

• a switch or tap which is fitted to the outlet of the plumbing fixture;

• a coarse filter for screening out solids and oils/greases;

• non-storage surge attenuation;

• an overflow device;

• a garden irrigation or distribution system.

The Australian Government provides guidelines regarding the distribution of grey water

via sub-surface irrigation distribution pipework (NSW, 2008b). Gravity diversion

systems allow diverted grey water to be directly fed to sub-surface irrigation areas for

the distribution of grey water (Figure 3.16). If necessary, grey water diversion systems

can incorporate water pumps to aid in the distribution of grey water.


73

Figure 3.16 Gravity-fed grey water diversion system for sub-surface irrigation.

Source: NSW (2008b)

According to the Australian guidelines, the sub-surface irrigation distribution pipework

should be buried at least 10 cm below surface level, with at least one meter distance

from each other, boundaries, buildings, swimming pools or underground potable water

tanks. Although Brazilian septic tank regulations NBR 13969 (ABNT, 1997) provides

some design guidelines for the distribution of drainage trenches, these are specified for

on-site wastewater disposal, not reuse. Grey water diversion is for productive use in

landscape irrigation, not the disposal of wastewater.

Figure 3.17 Detailed cross-section of irrigation trench for sub-surface irrigation

Source: (DHWA, 2002)

Although sub-surface irrigation distribution pipework can be composed of perforated

piped trenches, drip lines, irrigation domes or drippers, perforated pipes are cheaper and

easily available in the Brazilian market and therefore, piped trenches were considered as


74

the best option for analysis. Figure 3.17 on the next page provides a detailed cross-

section of an irrigation trench for sub-surface irrigation using perforated pipes for the

distribution of untreated grey water.

Grey water to be reused for surface irrigation, toilet flushing, floor, vehicle and clothes

washing require adequate treatment. Commercially available grey water treatment units

available in the Brazilian market are sold in pre-determined sizes, according to the

estimated volume of grey water to be treated (Alpina, 2010; Fito, 2010; Mizumo, 2010).

Figure 3.18 Generic composition of a GRW system

(a) Collection Pipework (b) Coarse Filter (c) Biological Treatment (d) Sediment Disposal (e) Fine Filtration/Activated Carbon

(f) Disinfection/Collection Tank (g) Overflow (h) Water Pump (i) Safety Control Unit (j) Header Tank (k) Solenoid Valve (l) Potable Water Feed (m) Distribution Pipework


Overall, these technologies include physical, chemical and/or biological treatment

processes for grey water treatment. According to Li et al. (2010), most of these

technologies are preceded by coarse filtration to avoid the subsequent clogging of the


75

system, and are followed by disinfection to meet the microbiological requirements. A

control unit can be used as a fail-safe mechanism to shut-off supply in case of

inadequate levels water treatment or system malfunction. Figure 3.18 illustrates a

generic composition of an indirectly pumped GWR system (Sant'Ana and Amorim,

2007)

Recently, a grey water reuse toilet and lavatory appliance unit has emerged in the

Brazilian market (Roca, 2010). Such appliance reuses grey water from the washbasin

for toilet flushing (Figure 3.19). Grey water from the washbasin passes through a

selective filtering system before it is fed into a small treatment tank for disinfection, and

hence, the grey water reuse unit requires periodic feed of 500 ml of bleach (5%

chlorine) for treatment. The equipment includes a bleach storage receptacle that releases

the bleach to the stored grey water according to its usage. Potable water can be fed into

the water closet cistern in case demand exceeds supply, and when not using for a long

period, the manufacturer suggests the extraction of grey water from the holding tank

through flushing. The equipment allows the user to select the use of grey water or

potable water for toilet flushing.

Figure 3.19 Grey water reuse toilet and lavatory appliance unit

Source: (Roca, 2010)


76

3.3.3 Wastewater reclamation systems

According to Winward et al. (2009) domestic wastewater is composed of all in-building

effluent streams, including toilet waste. Apart from rainwater and grey water, Winward

et al. (2009) argues that another urban water source available for non-potable reuse is

wastewater. Although uncommon, an increasing number of buildings are using

wastewater reclamation systems to treat domestic effluents on-site, producing non-

potable water for reuse (Wilson and Navaro, 2008).

Previous studies have shown that, provided with adequate treatment, wastewater can be

safely reused for non-potable domestic end-uses such as irrigation, toilet flushing, floor

and vehicle washing (i.e. Asano et al., 1986; Gaulke, 2006; Neal, 1996; Yokomizo,

1994).

3.3.3.1 Wastewater quality

Domestic wastewater effluents contain pollutant contributions from both grey water and

blackwater. Previous study has shown that toilet discharge contains the highest pollutant

contribution load to wastewater in five out of six determinants, for the exception of

nitrate, whose major contribution comes from kitchen sink discharge (Almeida et al.,

1999).

According to Asano et al. (1996) the most critical factor concerning wastewater reuse is

the protection of public health from pathogenic microorganisms. It is therefore crucial

that reclaimed wastewater meets the criteria established by ANA of non-potable water

quality standards so that it obtains adequate water quality characteristics and is not

aesthetically objectionable.


On-site wastewater reclamation (WWR) systems collect domestic sewage effluents for

non-potable end-uses after adequate water treatment. This can take place using two

schemes: (i) constructed wetlands, or (ii) treatment units.

Constructed wetlands act as a natural biological and physical treatment system capable

of removing both nutrients and pathogens from domestic wastewater, providing a water

quality suitable for reuse (Greenway, 2005; House et al., 1999). However, one of the


77

main problems in adopting constructed wetlands for water reuse in hot climate

countries, is that the high evapotranspiration rate can lead to significant water losses

during treatment (Masi and Martinuzzi, 2007). Furthermore, constructed wetlands

require space, and are more suitable in sites which require large volumes of water to be

treated.

Since this study deals with commercially available products that guarantee adequate

water quality levels for non-potable reuse to avoid health-related issues to residents, it

seemed prudent not to include constructed wetlands in the analysis.

Overall, wastewater treatment units consist of a combination of physical, chemical and

biological processes to remove suspended, settled and dissolved solids, organic matter,

metals, nutrients and pathogens from wastewater (Mujariego and Asano, 1999). The

Brazilian market offers small-scale treatment units for wastewater reclamation, which

are sold in pre-determined sizes, according to the estimated volume of effluent to be

treated (Alpina, 2010; Mizumo, 2010).

Figure 3.20 Small-scale treatment unit for wastewater reclamation

(1) Wastewater Inflow (2) Anaerobic Sedimentation Chamber (3) Anaerobic Filter Chamber (4) Aerobic Treatment Chamber (5) Sedimentation and Disinfection Chamber (6) Reclaimed Water Outflow

Source: (Mizumo, 2010)

Grease traps are often installed on kitchen sink discharge pipes in order to remove

grease and oils from kitchen wastewater to avoid the clogging of the system. Safety

control units are necessary to provide a visual alarm and shut down reclaimed water


78

supply in case of system malfunction. Figure 3.20 illustrates a small-scale treatment unit

for wastewater reclamation.

3.4 Conclusion

This chapter provided an overview of the state-of-the art domestic water conservation

measures for Brazilian dwellings. Overall, domestic water conservation measures are

capable of promoting the preservation of natural fresh water resources by reducing

water demand through efficiency and reuse.

Water efficient strategies are demand-side water conservation measures capable of

reducing water consumption through the improved effectiveness of water usage. A

range of commercially available water efficient technologies were identified and their

reduced flow rates or potential to reduce domestic water consumption addressed. The

main water efficient strategies selected for analysis included low flush and dual flush

toilets, automatic and sensor faucets, low-flow showerheads, flow regulators, high

efficiency washing machines, pressure washers, automatic shut-off nozzles, automatic

irrigation systems and leakage repair.

Water reuse systems on the other hand, are supply-side water conservation measures

which make use of alternative sources of water such as rainwater, grey water and

wastewater for non-potable reuse. Brazilian building regulations allow the use of

reclaimed water for non-potable domestic end-uses, as long as the necessary precautions

are taken to avoid mains water contamination and adequate treatment for reclaimed

water is provided, according to specific categories of non-potable water end-uses such

as garden irrigation, toilet flushing, floor, vehicle and clothes washing.

A range of commercially available water reuse systems in Brazil were identified,

ranging from simple manually operated water-butts to complex treatment units,

addressing water quality issues and system components and design. Table 3.3 on the

next page lists the water conservation measures that will be considered in the following

chapters for analysis.


79

Table 3.3 Water conservation measures considered for analysis

Water Conservation Measures

Water Efficient Strategies

Bathroom faucet flow regulator (1.8 l/min)

Automatic bathroom faucet

Bathroom sensor faucets

Low flow shower head (4.5 l/min)

Low-flush toilet (6 lpf)

Dual flush toilet (3/6 lpf)

Kitchen sensor faucet

Kitchen faucet flow regulator (1.8 l/min)

Utility faucet flow regulator (6 l/min)

High-efficiency washing machine

Automatic shut-off hose nozzle

Pressure washer

Automatic irrigation sprinkler system

Leakage repair

Water Reuse Systems

Rainwater harvesting system

Grey water recycling system

Wastewater reclamation system

Chapter 4 Methodological Approach

Methodological Approach

81

4. Methodological Approach

4.1 Introduction

There is a growing public awareness of water scarcity and its economic value. However,

quantifying potential savings from an array of water conservation strategies and demand

management practices for Brazilian dwellings can be difficult due to the lack of specific

and generalizable domestic water end-use consumption data. In order to evaluate the

effectiveness of demand-side and supply-side water conservation measures and identify

viable solutions to reduce domestic water consumption, it is crucial to quantify how

much water is consumed by each major domestic water fixtures and appliances and

understand how water is being consumed by residents in the household (De Oreo et al.,

1996; Jorgensen et al., 2009).

It is agreed among researchers that domestic water consumption varies according to a

series of variables, mostly based on dwelling characteristics (Loh and Coghlan, 2003;

Russac et al., 1991; Thackray et al., 1978; Troy and Randolph, 2005), social and

economic factors (Agthe and Billings, 1987; Conley, 1967; Dalhuisen et al., 2003;

Savenije, 2002; Schleich and Hillenbrand, 2009; Worthington and Hoffman, 2008),

climate (Billings, 1982; Dziegielewski et al., 1993; Foster and Beattie, 1979; Hoffmann

et al., 2006; Mayer et al., 1999) and occupant behaviour (Gregory and Di Leo, 2003;

Jorgensen et al., 2009; Randolph and Troy, 2008).

These explanations can vary from place-to-place leading to differences in the patterns of

water consumption. Countries with different national income are most likely to present

distinct patterns of domestic water consumption. Although numerous studies have fully

analysed domestic water consumption in developed countries, little research has been

carried out within developing economies (Potter and Darmame, 2010; Sivakumaran and

Aramaki, 2010; Zhang and Brown, 2005).

In Brazil, research on domestic water end-use consumption is still in its infancy, and

generalizable data has not yet been produced. Research carried out so far, has been

limited to two houses in Palhoça (Ghisi and Oliveira, 2007), three multi-storey

buildings in southern Brazil (Ghisi and Ferreira, 2007), one flat and seven houses in São


82

Paulo (Barreto, 2008; Rocha et al., 1998). In Brazil, there is a lack of specific domestic

water end-use consumption data of low, medium and high income dwellings, for the

different residential building typologies and their behavioural water usage. Furthermore,

as far as the literature goes, no study has analysed the impact of high differences in

household income on domestic water consumption, especially within the Brazilian

context, where social inequality is high

Having these issues in mind, the main objectives of this investigation are:

1. To measure domestic water consumption and understand how water is being

used by residents for the different income ranges and dwelling typologies in the

Federal District; and

2. To assess water end-use patterns between the different income ranges and

dwelling typologies in the Federal District.

The characterisation of domestic water end-use consumption has led to a series of

investigations to verify potential water savings from an array of water conservation

measures (i.e. Brewer et al., 2001; Griggs et al., 1998; Maddaus, 1984; Mayer et al.,

2003). While demand-side water conservation measures have been acknowledged to

promote water reductions through the use of water efficient strategies in residential

buildings (ANA et al., 2005; EA, 2007; Grant, 2006; Vairavamoorthy and Mansoor,

2006; Vickers, 2001), supply-side measures such as water reuse systems, make use of

alternative sources of water supply for non-potable end-uses such as garden irrigation,

toilet flushing, floor, vehicle and clothes washing to reduce domestic water

consumption (Ahn et al., 1998; EA, 2008a; EA, 2008b; Leggett et al., 2001a; Leggett et

al., 2001b; Tchobanoglous et al., 2003).

In Brazil, water conservation studies have focused in estimating the reductions

promoted by leakage repair (Oliveira, 2002) and use of flow regulators (ANA et al.,

2005) in multi-storey residential buildings, through the installation of water efficient

fittings, fixtures and appliances in low income houses (Vimieiro and Pádua, 2005), and

rainwater harvesting and greywater recycling systems in southern Brazil (Ghisi, 2006;

Ghisi et al., 2007; Ghisi and Ferreira, 2007; Ghisi et al., 2006; Ghisi and Oliveira,


83

2007). However, they fail to depict a comparative study of the potential water savings

obtained for both demand-side and supply-side water conservation measures according

to dwelling income range and building typology.

A number of studies have evaluated the economics of domestic water conservation

measures in developed countries (Arpke and Strong, 2006; EA, 2003; EA et al., 2007;

Marshallsay et al., 2007; Rahman et al., 2010; Roebuck et al., 2010; Waterwise, 2008),

however, these countries contain an improved economic setting, different from that of

developing countries. Little is known about the feasibility of the use of water

conservation measures within developing economies. Only one work has looked into

the cost-benefits of rainwater harvesting systems in Brazil (Júnior et al., 2008).

Therefore, further research is required in order to evaluate the feasibility of water

conservation measures in terms of their applicability and cost-benefits according to

building typology and household income.

In order to fill these gaps in knowledge, a third research objective is derived:

3. To identify and evaluate the feasibility of domestic water conservation measures

in terms of their applicability, water savings and financial benefits for different

income ranges and residential typologies.

Based on the hypothesis that variables such as household income, building typology and

occupant behaviour affect the way water is consumed, a methodology was designed to

address the aims of this study and to provide a generalizable tool for future research

capable of providing meaningful data over domestic water end-use consumption and

identifying feasible water conservation measures for the different income ranges and

building typologies. Figure 4.1 on the next page illustrates the overall methodological

approach designed to address the aims of the study.

Figure 4.1 Flow diagram of the methodological approachFlow diagram of the methodological approach


84


85

4.2 Case study site selection

The best approach to assess domestic water consumption and identify the feasibility of a

range of water conservation measures was through the use of statistically representative

sites and residential typologies of high, middle and low income dwellings. As a starting

point, this investigation has set out to understand and compare domestic water

consumption by cross referencing geo-demographic and socio-economic indicators as

well as secondary data of dwelling typology in the Federal District in order to point out

statistically representative regions for analysis.

4.2.1 Administrative region selection

The Federal District is currently composed of 29 administrative regions (AR). However,

data for the region as a whole was available only for 19 AR's. Using secondary sources

of statistical data obtained from the Federal District’s Water and Sewage Company

(Companhia de Saneamento Ambiental do Distrito Federal - CAESB, 2004) and the

Government’s District Household Survey (Pesquisa Distrital de Amostra por

Domicílios - PDAD, 2004), aggregate data for water consumption, household income

and dwelling typology were obtained for the 19 administrative regions (Table 4.1).

Eight administrative regions were selected for primary data collection on dwelling

characteristics, household income, water consumption, and occupant water use

behaviour through the use of questionnaire survey and water auditing.

4.2.1.1 The Federal District

Brasília was conceived by the urban planner Lúcio Costa, having its major buildings

designed by Oscar Niemeyer. The construction for Brazil’s new capital city started in

1956, and was inaugurated in April 21, 1960 by President Juscelino Kubitchek. Initially

planned for only 500,000 inhabitants, Brasília has seen its population grow much more

than expected. In order to accommodate such demand, new neighbourhoods and

satellite cities were created around Brasília. All together, the satellite cities, Brasilia and

its surrounding neighbourhoods compose the Federal District. Today, the Federal

District’s total population is now over 2,500,000 inhabitants. Originally, the Federal

District was undivided, and the entire region was administrated as a whole, but in 1964

it was split, for the first time, into 8 administrative regions (AR). Today, the Federal

District is currently divided into 29 administrative regions (Figure 4.1).


86

Figure 4.2 Administrative Regions of the Federal District.

Source: CODEPLAN (2006)

4.2.1.2 Geo-demographic indicators

Secondary data of monthly water consumption for the 19 administrative regions of the

Federal District were obtained from the water company (CAESB, 2005). Table 4.1

shows monthly water consumption for 19 administrative regions of the Federal District.

Overall, Brasília administrative region has the highest average monthly water

consumption and Candangolândia, the lowest.

Population figures obtained from (PDAD, 2004) were taken into consideration in order

to obtain a more reliable indicator for benchmarking water consumption. Although

Candangolândia presented a low volume of supplied mains water, it did not have the

lowest consumption rate. Ceilândia contained the highest number of inhabitants in the

Federal District and its monthly water consumption was less than half of Brasilia’s

domestic consumption.


87

Table 4.1 Geo-demographic indicators

Administrative

Region Total

Population

Av. Monthly Water

Consumption (m

3/month)

Av. Consumption Per

Capita (litres/person/day)

Brasília 198,906 2,841,440 476

Gama 112,019 597,771 178

Taguatinga 223,452 1,377,748 206

Brazlândia 48,958 169,439 115

Sobradinho 61,290 367,209 200

Planaltina 141,097 429,679 102

Paranoá 39,630 196,091 165

Núcleo Bandeirante 22,688 296,034 435

Ceilândia 332,455 1,301,646 131

Guará 112,989 819,746 242

Cruzeiro 40,934 596,943 486

Samambaia 147,907 625,343 141

Santa Maria 89,721 362,740 135

São Sebastião 69,469 166,077 80

Recanto das Emas 102,271 321,281 105

Lago Sul 24,406 498,348 681

Riacho Fundo 26,093 206,858 264

Lago Norte 23,000 299,217 434

Candangolândia 13,660 68,247 167

Federal District 2,096,534 11,541,857 184 Sources: PDAD (2004) and CAESB (2004)

Domestic water consumption per capita figures were obtained by cross-referencing

statistical water consumption data from CAESB (2005) with statistical population

survey from PDAD (2004).

Overall, the Federal District had an average domestic water consumption rate per capita

of 184 litres per person per day (l/p/d), Lago Sul administrative region contained the

highest water consumption rate of 681 l/p/d, and São Sebastião the lowest, only 80

l/p/d. Figure 4.2 on the following page presents the domestic water consumption rates

per capita for the 19 administrative regions. It is interesting to note that the regions of

highest income show water consumption greater than 434 litres per capita per day.


88

Figure 4.3 Average domestic water consumption per capita (litres/person/day)


4.2.1.3 Socio-economic indicators

Statistical figures of average monthly income rates for the administrative regions were

obtained from PDAD (2004) and are shown in Table 4.2. Following the Brazilian

Institute for Geography and Statistics standards for household income subdivision

(IBGE, 2000), the average monthly income data of dwellings was divided into 5 income

classes:

• Poor: Less than 1 minimum wage

• Low income: From 1 to 5 minimum wages

• Mid-low income: From 5 to 10 minimum wages

• Mid-high income: From 10 to 20 minimum wages

• High income: Above 20 minimum wages

The minimum wage in Brazil, during 2007, was equal to 380.00 Brazilian Reais per

month (R$/month), equivalent to 95.00 British Pounds. Table 4.2 shows the number of

minimum wage for each administrative region.

681486

476435434

264242

206200

178167165

141135131

115105102

80

0 100 200 300 400 500 600 700 800

Lago SulCruzeiro

BrasíliaNúcleo Bandeirante

Lago NorteRiacho Fundo

GuaráTaguatingaSobradinho

Gama Candangolândia

ParanoáSamambaiaSanta Maria

CeilândiaBrazlândia

Recanto das EmasPlanaltina

São Sebastião


89

Table 4.2 Socio-economic indicators

Administrative

Region

Average Dwelling Monthly Income

Average Income (R$/month)

No. of Minimum

Wages Income Range

Brasília 5,026 19.3 Mid-high Income

Gama 1,558 6.0 Mid-low Income

Taguatinga 2,493 9.6 Mid-low Income

Brazlândia 885 3.4 Low Income

Sobradinho 2,401 9.2 Mid-low Income

Planaltina 825 3.2 Low Income

Paranoá 1,361 5.2 Mid-low Income

Núcleo Bandeirante 2,157 8.3 Mid-low Income

Ceilândia 1,211 4.7 Low Income

Guará 3,186 12.3 Mid-high Income

Cruzeiro 3,155 12.1 Mid-high Income

Samambaia 1,039 4.0 Low Income

Santa Maria 962 3.7 Low Income

São Sebastião 1,362 5.2 Mid-low Income

Recanto das Emas 1,013 3.9 Low Income

Lago Sul 11,276 43.4 High Income

Riacho Fundo 1,535 5.9 Mid-low Income

Lago Norte 8,922 34.3 High Income

Candangolândia 2,150 8.3 Mid-low Income

Federal District 2,332 9.0 Mid-low Income Source: PDAD (2004)

The Federal District presented an average monthly income equivalent to 9 minimum

wages. Lago Sul and Lago Norte administrative regions had the highest income rate of

the Federal District, 43 and 34 minimum wages per month respectively, and were

classified as high-income administrative regions. Brasília, Guará and Cruzeiro were

classified as mid-high income administrative regions, whilst most of the administrative

regions of the Federal District belong to a mid-low income range. Ceilândia,

Samambaia, Recanto das Emas, Santa Maria, Brazlândia and Planaltina were low

income administrative regions, with average monthly income ranging between 1 and 5

minimum wages. Figure 4.4 shows the average monthly income rates (number of

minimum wages) from low to high-income classes for each administrative region.


90

Figure 4.4 Average dwelling monthly income in minimum wages

Source: PDAD (2004)

Figure 4.5 Relationship between income and water consumption

Source: PDAD (2004); CAESB (2004)

By cross-examining the average monthly water consumption rate for each

administrative region of the Federal District and their average monthly income rate, a

direct relationship between consumption and income could be noticed. Overall, high-

43.4

34.3

19.3

12.3

12.1

9.6

9.2

8.3

8.3

6.0

5.9

5.2

5.2

4.7

4.0

3.9

3.7

3.4

3.2

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

Lago Sul

Lago Norte

Brasília

Guará

Cruzeiro

Taguatinga

Sobradinho

Núcleo Bandeirante

Candangolândia

Gama

Riacho Fundo

São Sebastião

Paranoá

Ceilândia

Samambaia

Recanto das Emas

Santa Maria

Brazlândia

Planaltina

1

10

100

1,000

10,000

100,000

Bra

sília

Gam

a

Tagu

atin

ga

Bra

zlân

dia

Sob

rad

inh

o

Pla

nal

tin

a

Par

ano

á

N. B

and

eira

nte

Cei

lân

dia

Gu

ará

Cru

zeir

o

Sam

amb

aia

San

ta M

aria

São

Seb

asti

ão

R. d

as E

mas

Lago

Su

l

Ria

cho

Fu

nd

o

Lago

No

rte

Can

dan

golâ

nd

ia

Av. Domestic Water Consumption (l/p/d) Av.Dwelling Monthly Income (R$/month)


91

income administrative regions presented a high level of water consumption per capita,

whereas low-income administrative regions presented a low level of water consumption

per capita. Figure 4.4 presents this relationship for the 19 administrative regions,

indicating that, the higher the income, the higher water consumption tends to be and, the

lower the income, the lower the consumption rate.

Such relationship between income and water consumption might be explained through

behavioural aspects of water consumption between the income classes. High-income

families might increase their water consumption because they are easily capable of

paying for their water bills, and therefore squander water. On the other hand, low-

income families need to control their water consumption through behavioural actions

due to their limited monthly budget.

Another aspect to be taken into consideration would be dwelling typology. Such

relationship between water consumption and income can be explained by dwelling

characteristics such as built area, garden/yard area and even the number of water-

consuming features. For example, high-income dwellings tend to have a greater number

of fixtures and appliances, bigger garden area to irrigate, larger external floor area to

wash, and even a swimming pool. Low-income dwellings, on the other hand, tend to

have only the minimal number of fixtures and appliances, a small garden or yard, and

no swimming pool.

4.2.1.4 Dwelling typology

There are two types of dwellings in the Federal District: (i) houses and (ii) flats.

According to statistical figures of PDAD (2004), 78% of the residential dwellings in the

Federal District are houses, and the remaining 22% consist of flats. Table 4.3 shows the

number of houses and flats for each administrative region as well as their dominant

average dwelling size.

Lago Sul and Lago Norte administrative regions’ main dwelling typology consisted of

houses with an average built area ranging between 221m2 and 400m2. Ninety percent of

Brasilia’s residential stock consisted of flats, with most of them ranging between 61m2

to 120m2 of built area. Almost half of Núcleo Bandeirante and Cruzeiro administrative


92

regions were composed of flats with the average built area ranging from 61m2 to 120m2.

The remaining dwelling stock was mostly composed of houses between 41m2 and 90m2.

Table 4.3 Dwelling Typologies in the Federal District

Administrative

Region

Dwelling Typology Average Size (m

2) Houses Flats

Brasília 6,907 63,942 61 - 120

Gama 24,761 3,882 61 - 120

Taguatinga 47,383 11,721 61 - 120

Brazlândia 11,959 171 61 - 120

Sobradinho 13,580 2,231 Less than 60

Planaltina 32,965 806 61 - 120

Paranoá 8,772 159 Less than 60

Núcleo Bandeirante 3,034 3,147 61 - 120

Ceilândia 85,359 2,694 Less than 60

Guará 24,124 6,003 61 - 120

Cruzeiro 5,697 4,695 61 - 120

Samambaia 33,676 2,267 Less than 60

Santa Maria 21,726 994 61 - 120

São Sebastião 17,622 504 Less than 60

Recanto das Emas 23,692 392 Less than 60

Lago Sul 6,018 19 221 - 400

Riacho Fundo 5,541 998 Less than 60

Lago Norte 5,200 0 221 - 400

Candangolândia 3,432 209 61 - 120

Federal District 433,436 125,795 61 - 120 Source: PDAD (2004)

Figure 4.6 Relationship between built area and income

Source: PDAD (2004); CAESB (2004)

1.0

10.0

100.0

1000.0

Bra

sília

Gam

a

Tagu

atin

ga

Bra

zlân

dia

Sob

rad

inh

o

Pla

nal

tin

a

Par

ano

á

N. B

and

eira

nte

Cei

lân

dia

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ará

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zeir

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Sam

amb

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ta M

aria

São

Seb

asti

ão

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as E

mas

Lago

Su

l

Ria

cho

Fu

nd

o

Lago

No

rte

Can

dan

golâ

nd

ia

Av. Monthly Income (m.w.) Av. Built Area (m2)


93

Although there is a positive relationship between income and built area in the majority

of the administrative regions, some did not follow the pattern. Interestingly, dwellings

with the highest built area are part of the high-income administrative regions; however,

low-income administrative regions not necessarily presented the smallest built area

(Figure 4.5). For example, Brazlândia, Planaltina, and Santa Maria presented a lower

income and higher built area than Sobradinho, Paranoá and São Sebastião, having

61m2 - 120m2 of built area against less than 60m2.

For the majority of the administrative regions, there was a positive relationship between

built area and water consumption (Figure 4.6). However, five administrative regions did

not follow the pattern (Gama, Taguatinga, Brazlândia, Planaltina and Santa Maria).

Figure 4.7 Relationship between built area and water consumption

4.2.1.5 Selected administrative regions

The selection of the administrative regions for analysis took into consideration three

variables: (i) water consumption, (ii) income and (iii) dwelling typology (Table 4.4).

Two administrative regions were selected according to the four main income groups of

the Federal District in order to obtain a larger representative sample.

1

10

100

1,000

Bra

sília

Gam

a

Tagu

atin

ga

Bra

zlân

dia

Sob

rad

inh

o

Pla

nal

tin

a

Par

ano

á

N. B

and

eira

nte

Cei

lân

dia

Gu

ará

Cru

zeir

o

Sam

amb

aia

San

ta M

aria

São

Seb

asti

ão

R. d

as E

mas

Lago

Su

l

Ria

cho

Fu

nd

o

Lago

No

rte

Can

dan

golâ

nd

ia

Av. Domestic Water Consumption (l/p/d) Av. Built Area (m2)


94

Table 4.4 Summary of selected Administrative Regions for analysis

Administrative

Region Income Group

Domestic Water

Consumption

(l/p/d)

Dwelling Typology

Built Type Built Area (m2)

Lago Sul High 681 House 221 – 400

Lago Norte High 434 House 221 – 400

Brasília Mid-High 476 Flat 61 – 120

Cruzeiro Mid-High 486 Flat 61 – 120

Taguatinga Mid-low 206 House 61 – 120

Candangolândia Mid-low 167 House 61 – 120

Ceilândia Low 131 House Less than 60

Samambaia Low 141 House Less than 60

Source: PDAD (2004)

• Lago Sul and Lago Norte: Lago Sul and Lago Norte AR’s were selected for

analysis due to their similar typological profile of houses ranging from 221m2 to

400 m2, highest average water consumption ranging from 430 l/p/d to 680 l/p/d,

and mean household monthly income (R$9,000 – R$11,000).

• Brasília and Águas Claras: Brasília was selected for analysis because there is

a significant amount of habitants residing in flat dwellings in the Federal District

and it contains the largest number of flats (from 61m2 to 120m2 ) and household

income of R$ 5,000. Águas Claras is a new region in the Federal District and

has recently become an AR. Although aggregate statistical figures for this region

were not available, this AR was selected due to its large number of high-rise flat

dwellings and its large and fast growing population.

• Taguatinga and Candangolândia: Taguatinga and Candangolândia

administrative regions were selected mainly because their dominant dwelling

typology of houses range between 61 and 120m2 and because their water

consumption rate represent the average water consumption per capita of the mid-

low income group.

• Ceilândia and Samambaia: Celiândia and Samambaia contained the highest

number of habitants and were therefore capable of providing a significant

representative sample size for analysis, with a dominant house dwelling

typology of below 60 m2 and a household low monthly income of (R$ 1,000 –

R$ 1,200).


95

4.3 Primary data collection

In order to explore the relationship between domestic water consumption and three

variables: (i) residential dwelling typology, (ii) household income and (iii) occupant

water use behaviour; this research incorporated both quantitative and qualitative

methodological approaches. The first, involved a face-to-face questionnaire survey that

gathered primary data over socio-economic aspects of domestic water consumption and

dwelling characteristics over a stratified random sample size of 481 dwellings. The

second involved an in-depth analysis of end-use domestic water consumption with an

interview designed to understand resident water-consuming habits, and through a water

auditing technique developed, to measure, for seven days, domestic water end-use

consumption for 125 dwellings.

4.3.1 Questionnaire survey

The investigation made use of two types of questionnaires: a face-to-face questionnaire

and in-depth questionnaire. The face-to-face questionnaires were applied to house and

flat residents (Appendix A and Appendix B) in order to collect quantitative data on

dwelling characteristics (such as household size, income, tenure, monthly water

expenses, number of water-consuming equipments and features and existence of water

efficient fittings, fixtures or appliances) as well as public opinion (on mains water and

sewage tariffs, the importance of saving water and concern with future water resources),

awareness (of the existence of a range of water conservation measures) and acceptance

of water conservation measures (use of water conservation measures, dwelling retrofit

and willingness to pay). The in-depth questionnaires (Appendix C and Appendix D) on

the other hand, were used as part of the domestic water audit on houses and flats to

collect qualitative data on habits of water consuming activities at home (dish washing,

clothes washing, vehicle washing, floor washing, garden irrigation and water reuse), the

equipments used and water-saving attitudes in the home.

A distinction between the house and flat dwelling questionnaire was necessary mainly

due to typological differences in the way domestic water is metered, and in the way

outdoor water is used. Although every house in the Federal District is individually

metered, flats shared a common water meter. The great majority of residential multi-

storey buildings in the Federal District have one water meter to measure the domestic


96

water consumption for the entire building block. The water and sewage bill is divided

equally between the flats, and is commonly included as part of the condominium bills.

Although both built-types had similar indoor water-using amenities, residential building

blocks contained communal grounds and gardens which led to a distinct pattern of

outdoor water consumption. In order to collect primary data of building characteristics

(such as number of flats per floor, water metering and water bills), and to fully

understand habits of communal water consumption (floor washing and irrigation) and

the equipments used, it was necessary to create a different questionnaire directed to

building managers (Appendix E).

Face-to-face questionnaires were directed to 481 randomly selected dwellings of the

eight statistically selected AR’s of the Federal District, two of each AR representing an

income group: (i) high income, (ii) mid-high income, (iii) mid-low income and (iv) low

income. The face-to-face questionnaire was used to identify dwellings willing to take

part on a water audit to measure their water end-use consumption and an interview

designed to understand resident-consuming habits of water usage within dwellings. For

an in-depth understanding of domestic water end-use consumption, 125 questionnaires

were used as part of the domestic water audits.

4.3.2 Domestic water auditing

Residential water audits are capable of identifying domestic water end-use consumption

patterns. They make use of techniques which evaluate the processes in which water is

used, obtaining a balance of water input to, and output from a building, by measuring

the end-uses of domestic water consumption. In order to assess domestic water

consumption, this research created a simple, low budget method capable of measuring a

significant sample size of domestic water end-use consumption from different dwelling

types by adapting existing water auditing techniques of water measurements and

resident interviews.

To collect a significant sample size of primary data for domestic water end-use

consumption from different socio-economic profiles and dwelling typologies, 125 water

audits on residential dwellings were carried out (at least 30 audits per income range / 15

audits per Administrative Region). In order to obtain a set of reliable data, such in-depth


97

analysis consisted in measuring domestic water end-use consumption from dwellings

for a period of seven days, followed by a questionnaire designed to understand domestic

water-consuming activities and identify what equipments are being used during these

activities.

Dwellings willing to take part on the in-depth analysis of domestic water consumption

were identified through the use of the face-to-face questionnaire. Before the domestic

water audit started, it was crucial to fully explain the procedures to all family members

to engage them in recording their water consumption every day, for a period of seven

days. Residents were under no obligation to participate, and it was made clear that they

could withdraw from the survey at any time. Although the majority of family members

demonstrated a good level of participation, some participants felt that recording their

water consumption at all times became a bit tiresome towards the last day or two of the

auditing period. Three dwellings withdrew from the survey before the end of the water

auditing period, and therefore were not included in analysis.

In order to measure domestic water end-use consumption, one stop-watch was fixed

next to each tap-opening water fixture so that residents could easily register the time

water was used at each fixture, by simply pressing a button to start and pause the timer.

This stop-watch technique proved to be an effective, low-budget method for time-

tracking water use events, and it was capable of storing the timed data at each stop-

watch.

Due to the fact that toilets, washing machines and dishwashers contain a fixed-rate of

water consumption per use, diary-tracking cards were used to register the number of

times these appliances were used (Appendix F). For a seven day period, residents were

asked to record the number of toilets flushed daily by using diary cards fixed to the wall

next to each toilet. For washing machines and dishwashers, residents were asked to

record the day, number of uses and type of programme selected.

In order to obtain daily domestic water end-use consumption data, one resident was

asked to enter the number of ticks from toilet flushing, clothes washing, dish washing

and register the accumulated consumption time for every fixture at a summary card

(Appendix G), and reset all stop-watches for the next day. By using the number of water


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fixtures and appliances obtained from the face-to-face questionnaire, it was possible to

identify the number of bathrooms and other water-using amenities from a dwelling, to

prepare the diary-tracking summary card before site visit.

A full inventory of appliances, fixtures and other water-consuming features was carried

out in order to identify sources of water usage, quantify their flow rates and detect any

visible leaks. The flow rate of every tap-opening fixture (such as kitchen sink faucets,

wash basin faucets, showers, utility sink faucets, external taps, etc.) was identified by

measuring the time it took to fill up a one litre container by opening the tap half a turn

in order to obtain the average flow of a tap, thus obtaining its flow rate (litres per

second). The above data was registered on a water audit inventory form (Appendix H).

Prior measurements of these flow rates, residents were asked to demonstrate how they

usually operated every tap-opening fixture in order to obtain a more precise flow rate

measurement, according to their individual tap-opening habits. However, when

residents were not present, or unwilling to participate during inventory, tap-opening

fixtures were opened in a single wrist turn (equivalent to half a turn) in order to obtain

an average flow of water.

Flow rates of toilets were estimated according to the toilet cistern’s flushing volume (6,

9 or 12 litres). Water usage from washing machines and dishwashers could be obtained

from manufacturers' data sheets according to programme settings. The flow rates of

detected visible leaks were measured using a small measured container by recording the

time it took to fill up 1 ml, or estimated by using data on Table 3.1 (see Chapter 3,

Section 3.2.9) provided by ANA et al. (2005).

The water audit inventory was also used to collect background information about the

dwelling (built type, built area, garden/yard area, roof area, number of residents and

swimming pool volume) and to register the dates and meter readings before and after

the water audit.

After a full inventory of the water fixtures and appliances, and having set up the stop-

watches and diary-tracking cards next to each point of water use, residents were asked

for a recent water bill. The water bill shows data of monthly water consumption for the


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dwelling from the past 12 months as well as information on the water and sewage tariff

charged per consumption ranges. The data on the water bill was either written down on

the water audit inventory form, or photocopied and later returned to the residents at the

last day of the water audit.

4.4 Primary data analysis

The primary data collected from the in-depth questionnaire survey and domestic water

audits were used to assess domestic water consumption for the different socio-economic

dwelling typologies and identify their water end-use patterns. Baseline consumption

data of annual, monthly, weekly, daily and end-use water consumption benchmarks

were obtained and their water-consuming activities and habits analysed. The data

collected from both quantitative and qualitative approaches were used to compose

representative models for each of the different socio-economic dwelling typologies of

the Federal District based on a primary data set of dwelling characteristics, baseline

water consumption and resident opinion, awareness and acceptance. These models were

used to evaluate a range of water conservation measures in terms of their applicability,

water reductions and cost-benefits.

4.4.1 Baseline water consumption

Based on the measured fixture flow rates and the timed data of water end-uses collected

during domestic water auditing, it was possible to identify the volume of water

consumed daily per tap-opening fixture (Equation 4.1.). However, in order to obtain

daily water consumption figures from appliances such as toilets, washing machines and

dishwashers, appliance consumption rates per use were multiplied by the number of

uses recorded by residents during the domestic water audits (Equation 4.2).

�F = ��ℎH × 3600 + �LMN × 60 + OPQ� × RF (4.1)

Qf = Water Consumption per Fixture (litre) qf = Fixture Flow Rate (litre/second)

�S = T × RS (4.2)

Qa = Water Consumption per Appliance (litre) N = Number of Uses qa = Appliance Consumption Rate per Use (litre/use)


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Dealing with large data sets of timed and recorded consumption from fixtures and

appliances, an Excel model was created based on Equations (4.1) and (4.2) in order to

automate water end-use consumption calculations and simplify data analysis.

In order to validate the estimated domestic water end-use consumption an analysis using

metered data was carried out. Mains readings from each of the analysed house dwellings

were written down before starting the residential water audit and after its conclusion, in

order to obtain precise values of the total water consumption during the one-week

period of measurements. It was possible to compare the results from the total estimated

water consumption obtained from diary tracking with the total measured water

consumption from metered readings.

Dwellings that contained a discrepancy above or below 20% between estimated and

measured water consumption were discarded from analysis. Furthermore, the water bill

was collected in order to obtain not only the household’s annual water consumption, but

also to obtain its average monthly water consumption. With this, it was possible to

compare the dwelling’s metered consumption with its average consumption. Flats in the

Federal District were not individually metered. Residential building blocks used only

one mains water meter, and the bill equally shared between the flats. In this case, it was

impossible to use metered data for comparison.

Equation 4.3 shows that the average water consumption frequencies for tap-opening

fixtures were estimated by dividing their average daily water consumption (Qf) by their

measured flow rates (qf), whilst Equation 4.4 demonstrates how water consumption

frequencies for toilets, washing machines and dishwashers were estimated by dividing

their average daily water consumption (Qa) by their consumption rate per usage (qa).

UF = �FRF (4.3)

Ff = Fixture Frequency (min/day) Qf = Fixture Water Consumption (litre/day) qf = Fixture Flow Rate (litre/min)


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US = �SRS (4.4)

Fa = Appliance Frequency (uses/day) Qa = Appliance Water Consumption (litre/day) qa = Appliance Flow Rate (litre/use)

Average values obtained from measured domestic water end-uses were categorized

according to indoor and outdoor water consumption for benchmarking comparisons

between the different income dwellings. Water consumption per capita parameter of

litres per person per day (l/p/d) was used to benchmark the different sources of water

usage inside dwellings; however, in order to compare outdoor uses between different

residential typologies, a litre per area per day (l/m2/d) parameter was applied. Such

disaggregated values for both indoor and outdoor water end-use consumption were

aggregated into daily average figures of domestic water consumption per dwelling

(litres/dwelling/day) and per person (litres/person/day) for assessment.

In one hand, weekly water consumption figures, obtained from daily water consumption

averages, allowed an analysis of weekly variations in water consumption during

weekdays and weekends. On the other hand, mean monthly values of dwelling water

consumption obtained from historic billing records, allowed an evaluation of seasonal

variations in domestic water consumption by cross-referencing secondary climatic data

of precipitation and relative humidity.

4.4.2 Statistical analysis

In order to identify what lies behind domestic water consumption in dwellings with

different socioeconomic backgrounds and typological characteristics, a multivariate

statistical analysis was performed based on both sets of primary data collected from the

questionnaire survey and the domestic water audits, to explore the relationship between

independent variables of domestic water consumption and evaluate their level of

significance to model a domestic water demand function for the Federal District.

A descriptive analysis using mean values from variables related to dwelling income,

household size, residential typology and the number of water-consuming fixtures and


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appliances in the home was carried out for a better understanding on the composition of

dwellings with different built types and household income.

A correlation analysis between a series of variables related to domestic water

consumption, household composition and dwelling characteristics was performed and

their relationship measured using Pearson’s coefficient.

Coefficients which indicated a predictive relationship between variables of indoor and

outdoor water consumption were reported and used in a regression analysis to estimate

the domestic water consumption function. Multiple regressions allowed the

development of indoor and outdoor water consumption models generating a prediction

tool for domestic water consumption based on a set of explanatory variables.

Although results from domestic water auditing offered reliable domestic water

consumption data for domestic water end-use consumption according to income and

dwelling typology, it fails to provide and in-depth understanding of occupant behaviour

towards domestic water consumption, and perception of water conservation strategies.

A descriptive analysis of key water-consuming activities such as dish washing, clothes

washing, vehicle washing, floor washing and garden irrigation, as well as occupant

perceptions of water saving attitudes in the home were carried out according to dwelling

typology and dwelling income.

A descriptive analysis of resident’s opinion, awareness and acceptance of domestic

water conservation strategies provided a basis for understanding the level of concern

towards environmental issues and to identify how much occupant’s are willing to invest

in order to adapt their dwellings to reduce their consumption and promote water

conservation.

4.4.2.1 Drivers of domestic water consumption function

This section aims to understand what lies behind domestic water consumption and

review the main drivers of domestic water consumption. Numerous studies have

demonstrated that variables such as the cost of water, household income, climate,

dwelling characteristics, and occupant behaviour affect the way water is used and

should therefore be considered for water demand predictions.


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Empirical studies indicate that domestic water consumption is correlated with a series of

explanatory variables affecting domestic water demand (Espey et al., 1997). A series of

econometric models for domestic water demand estimations (Qd) have been derived

following the simple form in Equation 2.1, which relates water consumption in function

of price (P) and other factors (Z) such as income, household type and household

composition (Arbués et al., 2003).

�� = ��, � (4.5)

Qd = Domestic Water Demand P = Price Z = Other Independent Variables

4.4.2.2 Price of water

A great deal of economic research has been carried out over pricing policies as a

mechanism for managing domestic water consumption. The essential logic behind the

theory is that the higher the cost of water, the lower domestic water consumption is

(Shaw, 2005). This makes sense if water is considered as a pure economic good,

however, according to Savenije (2002), water is not a normal economic good. It

contains a number of characteristics, which makes it unique. Liu et al. (2003) argues

that the different uses of water, have different levels of economic values. For example,

in an extreme case, water, as a basic human need for survival, ceases to be an economic

good. On the other hand, once basic needs have been satisfied, surplus water can be

considered an economic good.

Numerous studies have shown that domestic water consumption tends to be price-

inelastic, that is, the decrease in consumption is lower than the increase in cost (see

Worthington and Hoffman, 2008). Arbués (2003) argues that in most cases water

demand is inelastic due to the fact that there are no substitutes for water and because

there is a low level of consumer perception on rate structures, since these represent a

very small fraction of household income.

It has been observed, however, that price elasticity varies according to a given use

(Conley, 1967). Essential water uses (i.e. drinking, cooking, personal hygiene, etc.) are

not affected by the cost of water and have low price elasticity. As a result, price increase

is expected to result in a small decrease in consumption. On the other hand, unessential


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water uses (i.e. landscape irrigation, car washing, swimming pools, etc.) are usually

affected by the cost of water and have a higher elasticity. As a result, price increase

would lead to changes in the way unessential water is used, or even, to the use of

alternative sources of water, in order to reduce consumption (Corbella and Pujol, 2009;


4.4.2.3 Household income

Numerous econometric models have been estimated using income as an independent

variable of water demand function (i.e. Agthe and Billings, 1987; Billings and Agthe,

1980; Dalhuisen et al., 2003; Hewitt and Hanemann, 1995; Niewswiadomy and Molina,

1989). Per capita income is commonly applied to models which make use of aggregated

water consumption data at the neighbourhood level, however, at the household-scale,

property value has been used as a substitute for household income because of their high

correlation (Dandy et al., 1997).

According to Dziegielewski et al. (1993) income measures the ability of residents to

pay for water, whereas the cost of water influences the amount of water residents are

willing to purchase. Both variables are capable of affecting domestic water consumption

behaviour. On one hand, low income linked with high water costs might cause residents

to modify their behaviour by reducing water irrigation, number of laundry loads, taking

shorter showers, making use of alternative water supplies, etc. On the other hand, high

income linked with low water costs might lead to a water-spending behaviour.

Generally, income is a measure of purchase power and is commonly associated with

living standards and level of education. Income can have an effect over the perception

of water cost. High income households might not be as responsive to water pricing as

low income households (Agthe and Billings, 1987). Living standards and property

characteristics are also affected by income. The basic premise is that the higher the

income, the higher the number of water consuming features in the household. Wealth

can be associated with the presence of a higher number of water fixtures and appliances,

larger gardens and swimming pool, affecting the way water is used (Corbella and Pujol,

2009). On the other hand, income has a positive correlation with education, and

therefore might be responsive to water conservation measures taken by residents


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through the purchase of water-saving equipment and adopting water drought-tolerant

garden vegetation (Worthington and Hoffman, 2008).

Worthington and Hoffman (2008) point out that estimates of income elasticity in the

literature indicate that domestic water consumption is income inelastic and small in

magnitude. Although results are consistent with income inelasticity, sample bias might

have a role to play. The authors argue that most studies were carried out in populations

with similar household income, and that domestic water demand might prove to be

income-elastic in an income-diverse situation, such as those found in developing

economies.

4.4.2.4 Household size

Daily per capita consumption (litres per person per day) is a common performance

indicator used to benchmark and forecast domestic water consumption (Wong and Mui,

2008). If domestic water consumption is measured at the household level, the number of

residents should have a positive association with water use, since occupancy has a direct

influence on water consumption. Studies demonstrate that household size is correlated

with domestic water consumption (i.e. Arbués et al., 2010; Barrett and Wallace, 2009;


It is expected that, the larger the number of residents in a household, the bigger the

consumption will be, however, it has been found that the increase in domestic water

consumption is less than proportional to the increase in household size (Arbués et al.,

2003; Worthington and Hoffman, 2008).

4.4.2.5 Dwelling Characteristics

Dwelling characteristics such as building typology, built area, garden area and water-

using facilities might influence the way water is used, and therefore affects the amount

of water consumed in a household. A series of studies indicate that domestic water

consumption varies according to residential building typology (i.e. Loh and Coghlan,

2003; Russac et al., 1991; Thackray et al., 1978; Troy and Holloway, 2004; Zhang and

Brown, 2005). Research carried out suggests that water consumption rates between the

different dwelling typologies are not significantly different from each other (Troy and


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Holloway, 2004; Zhang and Brown, 2005). However, an investigation carried out by

Russac et al. (1991) found that water consumption was higher in detached houses and

lower in flats.

Randolph and Troy (2008) explore variables of dwelling characteristics in Australia as

means to evaluate occupant behaviour towards domestic water consumption. According

to the authors, the ability to use water is dependent upon the range of water-using

facilities available in different residential building typologies. The number of water-

using facilities helps to explain how residents use their water and explain the differences

in water consumption behaviour. For example, flat dwellings tend to have a smaller

built area with fewer bathrooms, no gardens and swimming pools when compared to

house dwellings, thus limiting their potential to consume water, and therefore affecting

their behaviour towards domestic water consumption.

Another aspect of domestic water consumption to be taken into consideration is the fact

that water demand might be linked to built area, since the greater the floor area, the

higher the number of residents and water-using equipment (Memon and Butler, 2006).

According to Troy and Randolph (2005) the presence of water-using equipment can

influence the way water is used should be considered when studying behavioural

patterns of domestic water consumption. Rajala and Katko (2004) point out that

although domestic water consumption does not vary much according to built age of a

dwelling, the age of the water-using equipment has a more influential factor for

domestic water consumption.

A study focusing on indoor and outdoor domestic water usage for single and multi-

storey dwellings found that multi-storey dwellings used less water than single

residential dwellings (Loh and Coghlan, 2003). This might be attributed to the

typological characteristics of residential multi-storey buildings, since flat dwellings

contain communal garden areas, and therefore can have a lower water consumption rate

on outdoor activities than house dwellings with individual gardens.


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4.4.2.6 Climate

Domestic water consumption can be divided into seasonal and non-seasonal uses. The

first is related with activities such as irrigation and cooling, which are weather

correlated. The latter, is related with water-consuming activities that are not weather

correlated, such as toilet flushing and dishwashing (Dziegielewski et al., 1993).

Climatic factors can also influence domestic water consumption behaviour. High

temperatures can lead to changes in behaviour for cooling by increasing the frequency

of showers. Also, low levels of precipitation affect garden plants, and to maintain the

garden, occupant behaviour changes in order to provide supplement water for non-

native vegetation.

Precipitation regimes usually affect outdoor water consumption for garden irrigation.

Sources of water required to maintain garden plants generally comes from a

combination of rainfall and supplementary irrigation water during dry spells (Foster and

Beattie, 1979). Consequently, the lack of precipitation leads to an increase in water

consumption.

Although several water demand models have included different climatic parameters

such as temperature, precipitation and evapotranspiration (i.e. Billings, 1982; Hoffmann

et al., 2006; Mayer et al., 1999; Niewswiadomy and Molina, 1989), none of them seem

to have addressed relative humidity as a factor for outdoor water consumption for

garden irrigation.

Relative humidity is a measure of the amount of water vapour in the air and has a direct

relationship with precipitation and solar radiation. Relative humidity not only indicates

the likelihood of precipitation, but also is necessary for cloud formation. Therefore, low

levels of humidity imply in higher solar radiation, as clouds tend to decrease solar

intensity. Low relative humidity associated with high solar gain leads to high levels of

evapotranspiration, therefore increasing outdoor water demand for irrigation.


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4.5 Evaluation of water conservation measures

In order to identify feasible water conservation measures in terms of their applicability,

water savings and financial benefits for the different income ranges and residential

building typologies, four representative models were composed, one for each income

range, to represent: (i) high income dwellings, (ii) mid-high income dwellings, (iii) mid-

low income dwellings, and (iv) low income dwellings. Each representative model was

created according to the average values of primary data collected from the questionnaire

survey and domestic water audits for each income range.

Input data such as baseline water end-use consumption, number of residents, built area,

garden/yard area, roof area, number of fixtures and appliances and their measured flow

rates, were used to calculate domestic water reductions of water efficient technologies

and water reuse systems for the different income ranges and their residential typologies.

The representative models were also used as a basis to estimate capital costs and

evaluate the applicability of water conservation measures in terms of building

adaptation. Therefore, typological characteristics of dwellings (built area, plot size,

water-using amenities and typical plumbing installations) were considered for analysis.

Input data regarding public opinion towards the use and application of water efficient

technologies and water reuse systems, as well as the level of acceptance for dwelling

retrofit and the willingness-to-pay for water conservation strategies, were also applied to

the models in order to evaluate their applicability.

4.5.1 Domestic water reductions

The potential water savings of domestic water conservation measures are directly

related with a strategy’s capacity to reduce mains water consumption. Overall, domestic

water reductions (Qred) were obtained by the difference between baseline water

consumption (Qbase) and the estimated potential water savings (σw) for a determined

water conservation strategy (Equation 4.6).


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�VW� = �XSYW − Z[ (4.6)

Qred = Reduced Water Consumption (m3) Qbase = Baseline Water Consumption (m3)

σw = Water Savings (m3)

4.5.1.1 Water efficient fittings, fixtures and appliances

Water efficient fittings, fixtures and appliances are capable of promoting water savings

in dwellings. For this study, only commercially available water efficient equipments in

Brazil were considered for analysis. These included, flow regulators for lavatory,

kitchen and utility faucets, automatic lavatory faucet, lavatory sensor faucet, kitchen

sensor faucet, low-flow shower head, low-flush toilet, dual-flush toilet, high-efficiency

washing machine, automatic shut-off hose nozzle, pressure washer and automatic

irrigation system. Overall, the water savings (σw) for these strategies were determined

according to their potential water reductions (φr) (Equation 4.7).

Z[ = �XSYW − \�XSYW × ] ^V100_` (4.7)

σw = Water Savings (m3) Qbase = Baseline Water Consumption (m3) φr = Potential Reductions (%)

Potential reductions (φr) for low-flow rate water efficient fittings and fixtures were

obtained by dividing the average measured fixture flow rate (qf) with efficient fixture

flow rates (qef) gathered from manufacturer’s specifications (Equation 4.8).

^V = 100 − ab RFRWFc × 100d (4.8)

φr = Potential Reductions (%) qf = Fixture Flow Rate (litre/min) qef = Water Efficient Fixture Flow Rate (litre/min)

Potential reductions (φr) from water efficient appliances were obtained by dividing the

average appliance rate of consumption per use (qa) with the reduced water consumption

rates per usage (qea) gathered from manufacturer’s specifications (Equation 4.9).


110

^V = 100 − ef RSRWSg × 100h (4.9)

φr = Potential Reductions (%) qa = Appliance Consumption Rate per Use (litre/min) qea = Water Efficient Appliance Consumption Rate per Use (litre/min)

Potential reductions for water efficient equipment such as the automatic faucet, sensor

faucet, automatic shut-off hose nozzle and automatic irrigation system were obtained

from secondary sources based in previous studies. Due to their characteristics, these

water efficient strategies promote water reductions by controlling the frequency of

water usage. Equation 4.10 was used in order to estimate their reduced frequency (Fred).

UVW� = UXSYW − \UXSYW × ]^VW�100 _` (4.10)

Fred = Reduced Frequency (min) Fbase= Baseline Frequency (min) φr = Potential Reductions (%)

4.5.1.2 Rainwater harvesting systems

Reports on rainwater harvesting systems demonstrate that collecting rainwater from

rooftops is a simple concept that promotes self-sufficiency and saves mains water

because it can be used safely on non-potable end-uses such as irrigation, floor washing,

toilet flushing, clothes washing. In order to analyse the potential water savings from

rainwater harvesting systems, three types of rainwater demands were considered for

analysis:

• Reuse 1: Irrigation and floor washing

• Reuse 2: Irrigation, floor washing and toilet flushing

• Reuse 3: Irrigation, floor washing, toilet flushing and clothes washing

Although the different types of rainwater reuse described above have an effect on the

overall cost in plumbing installation and building adaptation, the main expenditure of

rainwater harvesting system lies within the rainwater tank size. Therefore, for each of

the above rainwater reuse types, simulations based on monthly time intervals using

Equation 4.11 for a series of storage volumes was carried out in order to identify water

savings for each storage volume.


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0� = 0�12 + �� − �� (4.11)

Subject to 0 ≤ Vt-1 ≤ C Vt = Volume in Store �m3 during time interval, t Vt-1 = Volume in Store �m3 during time interval, t-1 St = Rainwater Supply �m3 during time interval, t Qt = Rainwater Consumption �m3 during time interval, t C = Rainwater Storage Capacity

The average monthly rainwater supply (St) was obtained through the product of the

Federal District’s average historic monthly rainfall data (Rt) and dwelling average roof

area (A), considering the losses during runoff (Cr) and Filtration (Cf) (Equation 4.12).

�� = k� × l × V × F (4.12)

St = Rainwater Supply (litres) during time interval, t Rt = Average Rainfall (mm) during time interval, t A = Roof Area (m2) Cr = Runoff Coefficient Cf = Filter Coefficient

4.5.1.3 Greywater recycling systems

Greywater generated from bathroom (lavatory, shower and bath) and laundry (washing

machines and utility wash basins) can be reused for non-potable end-uses such as

irrigation, floor washing, toilet flushing and clothes washing. Four different types of

greywater systems were analysed. The first consisted in simply storing greywater from

the washing machine in a 300 litre greywater butt for irrigation and floor washing via

manual bucketing. The second system consisted of diverting greywater generated by the

premises for gravity fed sub-surface irrigation. The third, consisted of a commercially

available state-of-the-art greywater recycling apparatus composed of a single wash

basin and toilet unit linked together to treat greywater produced at the lavatory for toilet

flushing. The last, made use of commercially available greywater treatment units for

three types of greywater demands:





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Since greywater reuse systems are dimensioned according to the volume of greywater to

be supplied in a daily basis for reuse, sources of greywater were selected according to

the volume generated from bathroom and laundry in order to promote efficiency in the

greywater collection pipework retrofit and treatment. The collection of greywater in

existing residential buildings requires the interception of greywater outlets before they

reach the wastewater network. As result, the greater the numbers of interceptions, the

higher the costs involved in building adaptation. Furthermore, commercially available

greywater treatment systems are designed according to the volume of daily greywater

generated. For these reasons, an attempt to equalise the volume of greywater available

for treatment with the volume of greywater required to meet demand was sought

balance greywater demand and supply for the different types of reuses.

4.5.1.4 Wastewater reclamation systems

Traditionally, wastewater reclamation for non-potable reuse has been primarily been

done by centralized systems controlled by municipal water companies, however, in

recent years, commercially available small scale decentralized wastewater reclamation

systems have emerged in the Brazilian market. According to manufacturer’s,

wastewater reclamation systems are capable of providing adequate treatment and

disinfection to domestic wastewater for non-potable reuse in irrigation, floor washing

and toilet flushing. Hence, two types of domestic wastewater reuse were considered for

analysis:



Although collection pipework for wastewater reclamation systems require little or no

intervention to existing sanitary pipework installations, commercially available

wastewater treatment systems can be onerous. Although potable water savings from

wastewater reclamation systems were equivalent to reclaimed wastewater demand,

reclamation systems were dimensioned according to the total volume of wastewater

generated daily, given that commercially available wastewater treatment systems are

designed according to the volume of daily discharge of domestic wastewater.


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4.5.1.5 Water reduction index

In order to carry out an adequate evaluation of a comprehensive range of water

conservation measures, a water reduction index (WRI) was used as an indicator to

compare the level of potable water reductions promoted by different types of water-

saving strategies individually or in combination (Equation 4.13).

mkn = f�XSYW − �VW��XSYW g × 100 (4.13)

WRI = Water Reduction Index (%) Qred = Reduced Water Consumption (m3) Qbase = Baseline Water Consumption (m3)

4.5.1.6 Water consumption scenarios

Although water efficient strategies were evaluated individually, water reuse systems

were evaluated individually and in combination with water efficient strategies. Since

water efficient strategies reduce domestic water consumption, thus affecting water reuse

system dimensioning by decreasing water demand, and greywater and wastewater

supply. Hence, two scenarios were created to evaluate water reuse strategies. The first

scenario considered baseline water end-use consumption figures, and the second,

considered reduced water end-use consumption figures from a set of water efficient

strategies selected to promote maximum efficiency.

4.5.2 Applicability

The applicability of water conservation measures was determined according to (i)

public opinion, awareness and acceptance, and (ii) building adaptation. The average

values from the primary data collected from the questionnaire survey regarding public

opinion, awareness and acceptance of water conservation measures that served as input

data for the representative models, were used as a basis for evaluating the applicability

of a range of water conservation strategies. These were capable of measuring resident’s

awareness of existing water conservation strategies, acceptance over the use of water

efficient and water reuse strategies. Most importantly, these were able to evaluate if

residents were compliant to retrofit their homes, and pinpoint how much they would be

willing to pay to adapt their dwelling for water conservation, featuring both

environmental and financial benefits.


114

Typological characteristics of built form, built area, plot size and typical plumbing

installations, from each representative model were used as a basis to evaluate the

applicability of water conservation measures in terms of building adaptation. Such

information served mainly as a basis for water reuse system composition, dimensioning

and details of collection, drainage and distribution pipework, water tanks and equipment

installations, thus aiding in the estimation of their capital costs (including system cost

and installation costs) and operational costs (including energy consumption and

maintenance costs).

4.5.3 Cost-benefit analyses

Water conservation measures must answer two questions: (i) what are their costs? And

(ii) are they cost-effective? Their financial benefits were measured using three different

cost-benefit methods: (i) simple payback period, (ii) life cycle cost-benefit analysis and

(iii) average incremental costs.

4.5.3.1 Simple payback period

According to Herrington (2006), the simple payback period method identifies the length

of time, usually measured in years, it takes for an investment to generate enough

financial savings to repay the capital and other incurred costs of a determined water

conservation measure. Or, how long does it take for incoming return to cover its cost?

The main advantage of the payback period method is that it provides an easily

understood estimate of the benefits generated by a determined water conservation

measure from a customer point of view. Shorter payback period is considered the better

investment.

Assuming that, for the general public, the main incentive for investing in water

conservation measures is to save money, a simple payback period analysis was carried

out in order to verify which water conservation measures were most likely to be

invested by the general public. Primary data regarding the willingness-to-pay for water

conservation measures gathered from the questionnaires was used as a decision tool in

order to identify which measures were most likely to be invested by high, mid-high,

mid-low and low income residents.


115

To determine the payback period of a water-saving measure, its cost (Cm) and

installation expenses (Ci) were divided by the sum of the product of monthly water

savings (σw) and monthly costs of water (Cw) for the period of one year, subtracted by

the operational costs (Co) involved (Equation 4.14).

��o = p + q�∑ �Z[ × [2s2 � − t (4.14)

SPB= Simple Payback (yr) Cm = Cost of Measure (R$) Ci = Installation Cost (R$) σw = Water Savings (m3/month) Cw = Water Cost (R$/m3/month) Co = Operational Costs (R$/m3/yr)

Cost estimates for the above equipments, components and treatment systems were based

on the lowest price from at least three quotations obtained from local suppliers. Labour

costs were obtained according to the estimated number of labourer’s and days necessary

for commissioning, multiplied by the average daily rate of construction labour per

person in the Federal District. Annual energy consumption for electrical equipment was

estimated by the product of the equipment’s electric power by its total annual frequency

of usage.

The payback period does not take into account the distribution of costs and savings over

time and ignores the total savings generated over the lifetime of the equipment.

Furthermore, it does not provide a simple decision-rule of acceptance or rejection of the

equipment.

4.5.3.2 Life cycle cost-benefit analysis

Since the simple payback method offers no data regarding the financial benefits of a

determined investment over the useful lifetime of a water conservation measure, a life

cycle cost benefit analysis was carried out in order to take into account all the benefits

and relevant costs during a measure’s lifespan, including the adjustment for time value

of money. Life cycle cost analysis is an economic evaluation technique that determines

the total cost of owning and operating a facility over a period of time.


116

The life cycle cost-benefit analysis compares the total benefits generated by the

different water conservation measures during their useful lifespan, using the annual

discount rate to summarize findings into a measure of net present value (NPV) as

described in Equation 4.15.

T�0 = −uv + w o� − ��1 + H�x

�yv (4.15)

NPV = Net Present Value (R$) K0 = Capital Costs in year zero (R$) Ct = Costs in year t (R$/yr) Bt = Benefits in year t (R$/yr) r = Annual Discount Rate (%) n = Useful lifespan (yr)

The annual discount rate reflects time preference, i.e., people prefer experiencing

benefits sooner than later and facing costs later than sooner. Through discount rate the

present value of a benefit arising in the future is estimated in present value terms.

Basically, the discount rate is the interest rate that would make an investor indifferent as

to whether receive a payment now or a greater payment in the future.

Negative figures of net present value indicates that the costs of a determined water

conservation measure is greater than the benefits generated during the measure’s life

time, and thus, is considered unviable. Positive values on the other hand, indicates that

the benefits generated by a measure during its useful life is greater than the costs, and

consequently, the highest NPV figures are the preferred option as these indicate the

level of financial gains promoted by a water conservation measure.

A discount rate of 3% per annum was used for discounting future costs back to

equivalent present values. This rate is an average of the two most used interest rates in

Brazil: TR (referential rate of return, in Portuguese), which is used on loans, deferred

payment and general insurance, and TJLP (long run interest rate, in Portuguese), which

is the rate of return used on government bonds and popular savings.

The 3% discount rate was estimated according to the average values of reference

interest rates and long term interest rates from June 2009 to June 2010, obtained from

Brazil’s Central Bank (Brasil, 2010).


117

The average life expectancy for each water conservation measure, was estimated

according to secondary sources, or obtained from manufacturers (Tables 4.5 and 4.6).

Although water reuse systems were estimated to contain a useful life of 30 years, mostly

due to the indicative life expectancies of the PVC pipework, water tanks and treatment

units, the life cycle cost-benefit analysis considered the costs for component

replacement during their lifespan.

Due to the fact that a state-of-the-art greywater reuse toilet and lavatory unit has been

recently introduced in the market, no life cycle data could be estimated. However,

considering the fact that such apparatus is composed of a one-piece ceramic toilet and

wash basin appliance, the same indicative life cycle of average 23 years for toilets was

considered for analysis.

Table 4.5 Estimated life expectancies used for water efficient strategies.

Water Efficient Strategy Indicative

Life Expectancy

Estimated

Life Expectancy

Bathroom Faucet Flow Regulator Aerator 10 - 30 yrsb 20 yrs

Automatic Bathrom Faucet 10 - 30 yrsb 20 yrs

Bathroom Sensor Faucets 10 - 30 yrsb 20 yrs

Low Flow Shower Head 5 yrsa 5 yrs

Low-Flush Toilet (6 lpf) 15 - 30 yrsa 23 yrs

Dual Flush Toilet (3/6 lpf) 15 - 30 yrsa 23 yrs

Kitchen Sensor Faucet 10 - 30 yrsb 20 yrs

Kitchen Faucet Flow Regulator Aerator 10 - 30 yrsb 20 yrs

Utility Faucet Flow Regulator 10 - 30 yrsb 20 yrs

High-Efficiency Washing Machine 10 yrsa 10 yrs

Automatic Shut-off Hose Nozzle 5 yrsc 5 yrs

Pressure Washer 5 yrsd 5 yrs

Automatic Irrigation Sprinkler System 5 - 10 yrsc 7.5 yrs

Leakage Repair 10 – 50 yrs 30 yrs

a. Environment Agency (2003); b. Fernando Saibro from Fabrimar p.c. July 2010; c. GARDENA Manufacturing GmbH p.c. July 2010; d. Fernanda Mosquiar from Karcher Brasil p.c. July 2010

Table 4.6 Estimated life expectancies used for water reuse system components.

Water Reuse System Components Indicative

Life Expectancy

Estimated

Life Expectancy

Pipework (PVC) Over 20 yrsa 30 yrs

Pumps 5-10 yrsa 7.5 yrs

Filters (self-cleaning) 10-15 yrsa 12.5 yrs

Solenoid Valves 5-10 yrsa 7.5 yrs

Float Valves 10-15 yrsa 12.5 yrs

Level Switches 10-15 yrsa 12.5 yrs

Rainwater Tank Over 20 yrsa

30 yrs

Greywater Treatment Unit 10-50 yrsb 30 yrs

Wastewater Treatment Unit 10-50 yrsb 30 yrs

a. Leggett et al. (2001b); b. Rafael Souza from EcoCasa p.c. July 2010


118

4.5.3.3 Average incremental cost-benefit analysis

Surely, when comparing results for the life cycle cost-benefit analysis, the higher the net

present value, the bigger the financial benefits for a determined water conservation

measure. However, it might be difficult to appraise different types of water conservation

strategies, of different scales and lifespan. Therefore, an average incremental cost-

benefit analysis was used in order to compare the cost effectiveness of large initiatives

with that of smaller ones by scaling NPV results as a rate of financial benefit per

volume of water saved within the same time horizon.

The average incremental cost (AIC) of a water conservation measure could be identified

as the net present value of a series of incurred future capital and operational costs of a

measure to provide a service, divided by the incremental output of total water saved

during a determined time horizon (Equation 4.16). This has allowed a comparison

between different water conservation measures in terms of their cost per cubic meter of

water saved (R$/m3).

ln = − eu − o + tZ[ h (4.16)

AIC= Average Incremental Cost (R$/m3) K = NPV of Capital Costs (R$) B = NPV of Benefits (R$) Co = NPV of Operational Costs (R$) σw = Total Water Savings (m3)

Given the fact that water reuse systems contained the oldest average life expectancy

equivalent to thirty years, a time horizon of 30 years was used level out the different life

cycles of the varied water conservation measures. Capital costs related to the

replacement of fittings, fixtures, appliances and the main equipments related to the

proper functioning of a determined water conservation measure once they reached their

average life expectancies was incurred during the thirty-year analysis (see Tables 4.5

and 4.6).

The three methods above were used as a filtering criterion to identify economically

viable water conservation measures. Initially, the simple payback method was used to

quickly eliminate unrealistic options which contained periods of financial return above a

measure’s lifespan, or demonstrated higher annual operational costs than annual


119

financial benefits. Then, a life cycle cost-benefit analysis was used to rule out any water

conservation measure with costs greater than their financial benefits generated during

the measure’s life expectancy. Lastly, results from average incremental cost-benefit

analysis were presented on a comparable level of cost per unit of water saved, which

allowed us to rank and compare the benefits generated from the remaining water

conservation measures in a 30 year time horizon.

4.6 Conclusion

This chapter has described the methods used to (i) measure domestic water end-use

consumption for the different socio-economic dwellings in the Federal District, (ii)

evaluate the feasibility of a range of water conservation measures according to income

and residential typology, and (iii) to understand the way water is used and to review the

main drivers of domestic water consumption. Table 4.7 summarises the methodological

techniques used for data collection and the evaluation of water conservation measures.

By cross-referencing geo-demographic and socio-economic secondary data, the

selection of the administrative regions for analysis took into consideration water

consumption, income and dwelling typology. Two administrative regions were selected

for each of the 4 main income groups of the Federal District:

• High Income: Lago Sul and Lago Norte Administrative Regions

• Mid-High Income: Brasília and Águas Claras Administrative Regions

• Mid-Low Income: Taguatinga and Candangolândia Administrative Regions

• Low Income: Ceilândia and Samambaia Administrative Regions

Table 4.7 Methodological techniques for data collection and evaluation of water

conservation measures

Primary Data Collection methods and key parameters

Questionnaire Survey

Face-to-face questionnaire

- Dwelling characteristics (household size, income, tenure, estimated monthly water expenses, number of water-consuming equipments and features and existence of water efficient fittings, fixtures or appliances).

- Public opinion (on mains water and sewage tariffs, individual water

metering, the importance of saving water and concern with future water resources).

Continues on the next page


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- Awareness of the existence of a range of water conservation measures. - Acceptance (of water conservation measures, dwelling retrofit and

willingness to pay.

In-depth questionnaire

- Habits of water-consuming activities (dish washing, clothes washing, vehicle washing, floor washing, garden irrigation and water reuse).

- Equipments used during water-consuming activities. - Water-saving attitudes.

Domestic Water Auditing

Water audit inventory

- Dwelling characteristics (built type, built area, garden/yard area and roof area).

- Type and number of water fixtures and appliances. - Volume of swimming pool and other water-consuming features. - Alternative sources of water (groundwater, rainwater and greywater). - Fixture flow rate (litres/second). - Appliance consumption rate per use (litre/use). - Detection of visible leaks and estimation of water loss.

Stop-watch technique - Daily timed water use events of tap-opening fixtures.

Diary-tracking technique - Daily registered water use events of toilet flushing, washing machine

and dishwasher appliances.

Mains water metering - Weekly measured water readings prior audit outset and after audit

closure.

Water and sewage bill - Monthly water consumption for the last 12 months. - Water and sewage tariff charged per consumption range.

Evaluation of water conservation measures

Domestic water reductions

Water efficient fittings, fixtures and appliances

- Water savings from low flow fittings and fixtures determined according to reduced flow rates obtained from manufacturer’s specifications.

- Water savings from water efficient appliances determined according to

reduced consumption rates per use obtained from manufacturer’s specifications.

- Water savings from automatic equipment determined using secondary

sources. Rainwater harvesting systems

- Water savings from three different demands determined using behavioural simulation for the operation of varied storage capacities.

Greywater recycling systems

- Water savings for four different types of greywater systems determined according to the balance of greywater supply and demand.

Wastewater reclamation systems

- Water savings determined according to reclaimed wastewater demand.

Water reduction index - Compares the level of water potable water reductions promoted by different types of water conservation measures individually or in combination.

Scenarios - Baseline scenario (water savings estimated according to current

domestic water end-use consumption). - Reduced scenario (water savings estimated for water reuse systems

according to the highest level of achievable water efficiency in domestic water end-use consumption).

Continues on the next page


121

Financial benefits

Simple payback period - Verifies which water conservation measure is most likely to be invested by residents, considering public opinion and willingness-to-pay.

- Eliminates unrealistic options (periods of financial return greater than

the measure’s lifespan, or operational costs are higher than financial benefits).

Life cycle cost-benefit analysis

- Compares the total benefits generated by different water conservation measures during their useful lifespan using net present value at a 3% discount rate.

- Negative values indicate that the costs of a water conservation measure

are greater than the benefits generated during the measure’s life time, thus, unviable.

Average incremental cost-benefit analysis

- Compares the cost effectiveness of large initiatives with that of small ones by scaling results as a rate of financial benefit per volume of water saved within a 30 year time horizon.

Applicability

Public acceptance - Verifies acceptance over the use of water efficient fittings, fixtures and appliances, rainwater harvesting systems, greywater recycling systems and wastewater reclamation systems at home.

- Verifies acceptance of dwelling retrofit and level of willingness-to-pay.

Building adaptation - Verifies physical constraints and extreme costs related to building refurbishment and plumbing installations.

In order to explore the extent to which dwelling typology, socio-economic

characteristics and occupant behaviour influence domestic water consumption, this

research incorporated both qualitative and quantitative and qualitative data collection

methods. The former involved a large-scale questionnaire survey directed to residents

for the above selected administrative regions, and the latter approach implicated in

conducting an in-depth analysis inside the dwellings, through the use of water auditing

techniques of water consumption measurements and resident interviews.

The primary data collected from the in-depth questionnaire survey and domestic water

audits were used to assess the domestic water consumption of the different socio-

economic dwelling typologies in terms of their annual, monthly, weekly, daily and end-

use water consumption, as well as to understand water-consuming activities and habits

in the home.


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Based on the data collected for dwelling characteristics, baseline water consumption,

and resident opinion, awareness and acceptance collected from both qualitative and

quantitative approaches were used to compose a representative model for each of the

different socio-economic dwelling typologies. These representative models were used to

identify feasible water conservation measures in terms of their applicability, water

reductions and cost-benefits.

Three different methods were used to measure the financial benefits of water

conservation measures: (i) payback period (number of years to pay back initial costs),

(ii) life-cycle analysis (present value of future savings), and (iii) average incremental

cost analysis (cost per cubic meter of water saved).

Correlation and regression analysis were carried out in order to estimate the demand

function for indoor water as a function of number of residents, dwelling income, cost of

water, and built area. A demand for outdoor water, as a function of cost of water and

garden area, was estimated.

Chapter 5 Domestic Water Baseline Consumption

Domestic Water Baseline Consumption

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5. Domestic Water Baseline Consumption

5.1 Introduction

As seen in chapter 4, occupant behaviour is the most important factor in determining

domestic water consumption, which is a function of (i) situational influences (household

income, number of residents, cost of water); (ii) unreasoned influences (habits and

routines); (iii) reasoned influences (attitudes); and (iv) stimulus (governmental

subsidies, environmental knowledge).

Based on the hypothesis that variables such as dwelling income, building typology and

occupant behaviour affect the way water is consumed, this chapter describes the results

obtained from fieldwork and discusses domestic water consumption and its end-uses for

different residential building types of high, mid-high, mid-low and low income

dwellings in the Federal District; exploring the way occupant behaviour has a direct

influence over the way water is used at home.

An econometric model and correlation analysis, using primary data collected in field

work, have been estimated for the demand function of domestic water in order to

understand what lies behind domestic water consumption in the Federal District.

5.2 Primary data collection

In order to assess the current domestic water consumption for the high, mid-high, mid-

low and low income dwellings of the Federal District, this research incorporated both

quantitative and qualitative methodological approaches. The first, involved a face-to-

face questionnaire survey that gathered primary data over socioeconomic aspects of

domestic water consumption such as dwelling characteristics, public awareness and

acceptance of water conservation strategies over a stratified random sample size of 481

dwellings. The second involved an in-depth analysis of domestic water end-use

consumption with a questionnaire designed to understand resident water-consuming

habits, and through a water auditing technique developed by the author to measure, for

seven days, end-use consumption for 117 dwellings. Primary data collection was

undertaken during the period of January 2008 to December 2008.


125

5.3 Dwelling characteristics

Dwelling characteristics for the high, mid-high, mid-low and low household income

were obtained from both quantitative and qualitative methodological approaches.

Parameters such as income, number of residents, tenure, built type, built area, garden

and roof areas, number of water fixtures and appliances, swimming pool and water bill

were analysed and their findings discussed.

5.3.1 Income

Through a face-to-face questionnaire, 481 residents were asked to inform their

dwelling’s gross income. In total, 12% of the respondents did not know or refused to

provide the dwelling’s gross monthly income. From those who did answer, 2% of the

dwellings were rated as poor (less than R$ 400 monthly), 23% presented a low income

(between R$400 and R$2,000 per month), 20% had a mid-low income (between

R$2,001 and R$4,000), 18% with mid-high income (between R$4,001 and R$8,000)

and 26% of the dwellings presented a high income (above R$8,000 per month) (Figure

5.1).

Figure 5.1 Income ranges of dwellings

In line with the statistical figures published by PDAD (2004), Lago Norte and Lago Sul

dwellings presented a high average income range of more than R$8,000 per month,

Brasília and Águas Claras dwellings with an average mid-high monthly income range

between R$4,001 – R$8,000, while Taguatinga and Candangolândia dwellings had a

mid-low monthly income average of R$2,001 – R$4,000 and most of Ceilândia and

Samambaia dwellings had a monthly low income of R$400 – R$2,000 (Figure 5.2).

0%

5%

10%

15%

20%

25%

30%

Less than R$400

R$400 -R$2000

R$2001 -R$4000

R$4001 -R$8000

More than R$8000

Don't Know


126

Figure 5.2 Dwelling income range per administrative regions.

Table 5.1 shows the average income per administrative region obtained from the face-

to-face questionnaire survey. The administrative regions of Ceilândia and Samambaia

had the lowest average monthly income per dwelling of R$3,200 (£914) and an average

income per capita of R$800 (£229) per person per month. Taguatinga and

Candangolândia had an average monthly income of R$4,000 (£1,143) and an average

R$1,200 per capita (£343 per person per month).

Table 5.1 Average income per administrative regions

Administrative Regions Av. Income per Dwelling Av. Income per Capita

m.m.w. R$/month £/month m.m.w R$/month £/month

Lago Norte / Lago Sul 24 9,600 2,743 6 2,400 686

Brasília / Águas Claras 19 7,600 2,171 7 2,800 800

Taguatinga / Candangolândia 10 4,000 1,143 3 1,200 343

Ceilândia / Samambaia 8 3,200 914 2 800 229

m.m.w: monthly minimum wage

The average monthly income of Lago Norte and Lago Sul dwellings was R$ 9,600

(£2,743) and a monthly income per capita of R$2,400 (£686), while Brasília and Águas

Claras presented an average income per dwelling, of R$ 7,600 (£2,172), and a monthly

income per capita of R$2,800 (£800). The household income varies form an equivalent

to 24 minimum wage to 8 minimum wage. The income of Lago Norte/Lago Sul region

0%

10%

20%

30%

40%

50%

60%

70%

80%

Less than R$400

R$401 -R$2000

R$2001 -R$4000

R$4001 -R$8000

More than R$8000

Don't Know

Lago Norte / Lago Sul Brasília / Águas Claras

Taguatinga / Candangolândia Ceilândia / Samambaia


127

(high income) is three times higher than that of Ceilândia/Samambaia (low income)

region.

5.3.2 Household size

The questionnaires also evaluated the number of residents per dwelling. It was observed

that the majority of high income dwellings had maids and, in some cases, gardeners or

housekeepers, who had a place to stay in the household, and therefore, these workers

were considered as residents of the dwelling due to the fact that they are key-consumers

of water. Mid-high income dwellings had maids that would come to work on a daily

basis and return to their own homes at evening or, would either work 1 to 3 days during

the week. In this case, they were not considered as residents. Few mid-low income

dwellings had maids working at the home and no low income dwelling had a maid.

High income dwellings (Lago Norte and Lago Sul), mid-low income dwellings

(Taguatinga and Candangolândia), and low income dwellings (Ceilândia and

Samambaia) presented an average of 5 residents per dwelling, while mid-high income

dwellings (Brasília and Águas Claras) had the lowest number of residents, an average 3

residents per dwelling. Taking all the income groups together, the average was equal to

4.3 residents per dwelling in the Federal District.

Table 5.2 Number of residents per dwelling by income group

No. of Residents High Income Mid-High Income Mid-Low Income Low Income

1 --- 7.6% 3.4% 0.9%

2 10.7% 29.5% 8.1% 11.3%

3 15.2% 21.0% 21.5% 17.4%

4 24.1% 23.8% 25.5% 28.7%

5 25.9% 14.3% 18.1% 19.1%

6 15.2% 3.8% 5.4% 10.4%

7 5.4% --- 4.7% 6.1%

8 0.9% --- 6.0% 1.7%

9 --- --- 2.0% ---

10 or above 2.7% --- 5.4% 3.5%

Total Average (4.6) 5 Residents (3.2) 3 Residents (4.6) 5 Residents (4.5) 5 Residents

5.3.3 Tenure

Overall, the results of the primary data collected from the questionnaire surveys,

indicated that almost 80% of the respondents were outright owners of their homes,

while the remaining 20% of the respondents were renting privately. High income


128

dwellings had the lowest number of rented dwellings (12%) whilst mid-high income

dwellings presented the highest number of rented dwellings (29%) (Figure 5.3).

Figure 5.3 Tenure of dwelling property by income group

5.3.4 Residential typology and amenity characteristics

Typological characteristics are determinants for water use within homes, and therefore,

through an in-depth analysis of 117 dwellings, primary data regarding the home’s built

type, built area, roof area, garden/yard size, swimming pool and other water features

were collected according to administrative regions (Table 5.3). Due to the Federal

District’s urban planning laws, a distinct pattern of typological characteristics per

administrative region could be found.

Table 5.3 Typological characteristics

Typological Parameters High Income Mid-High

Income

Mid-Low

Income Low Income

Built Area (m2): 427 91 141 110

Garden / Yard Area (m2): 1,364 --- 80 74

Roof Area (m2): 373 765 130 97

Swimming Pool Volume (m3): 53 --- 35 ---

5.3.4.1 Lago Norte and Lago Sul: High income dwellings

Lago Norte and Lago Sul dwellings were either ground floor bungalow houses (65%) or

one story detached houses (35%) with an average total built area of 427m2. Due to strict

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

High Income Mid-High Income Mid-Low Income Low Income

Owned Rented


129

local land use planning laws, the constructible area within an average 1,738m2 plots are

limited, and therefore contain average roof projections of 373m2 and extensive

vegetated gardens of 1,364m2. Almost every home had an extension with a barbeque

area next to a swimming pool (average volume of 53m3). (Figure 5.4).

Figure 5.4 Aerial view of high income houses in Lago Sul.

Source: http://www.infobrasilia.com.br

5.3.4.2 Brasília and Águas Claras: Mid-high income dwellings

All of Brasília and Águas Claras dwellings were flats, with an average built area of

91m2. Having different urban planning laws, Brasilia and Águas Claras residential

building blocks differed in size and built form.

Due to Brasilia’s urban planning, the residential building stock consisted of dominantly

horizontal high rise buildings with 4 or 6 storey high rise buildings (Figure 5.5). With

an average roof area of 1,095m2, the number of flats per floor varied from 8 to 16.


130

Figure 5.5 Aerial view of mid-high income residential buildings in Brasília.

Source: http://www.infobrasilia.com.br

Águas Claras’ residential building stock on the other hand, had a dominant vertically

shaped high rise buildings ranging from 12 to 25 storey high (Figure 5.6). Most

residential buildings contained 4 flats per floor, having an average roof area of 434m2.

Figure 5.6 Mid-high income residential buildings in Águas Claras.

Source: http://pt.wikipedia.org/wiki/Ficheiro:Aguas_Claras_2007.JPG


131

Flat dwellings from both Brasília and Águas Claras, did not have individual gardens,

these were commonly found within communal grounds surrounding the residential

building blocks. From the analyzed sample, no swimming pools were found, however,

some recently built residential buildings contain communal pools, and a few penthouses

have an individual pool.

5.3.4.3 Taguatinga and Candangolândia: Mid-low income dwellings

The majority of the dwellings from Taguatinga and Candangolândia were ground floor

bungalow houses (86%) the remaining were one story detached houses (14%). With an

average dwelling built area of 141 m2, the houses had an average roof area of 130m2.

These homes did not have a vegetated garden, instead, they had cemented yards of an

average 80m2 (Figure 5.7). Few of Taguatinga and Candangolândia dwellings did have

a swimming pool (3.5%), with an average volume of 35m3. No water features were

found within the dwellings.

Figure 5.7 Aerial view of mid-low income houses in Taguatinga

Source: Google Earth

5.3.4.4 Ceilândia and Samambaia: Low income dwellings

Dwellings from Ceilândia and Samambaia were either ground floor bungalow houses

(85%) or one storey terraced houses (15%) with an average built area of 110m2. Having

an average roof area of 97 m2, most dwellings analysed had cemented yards with an

average 74m2 area (Figure 5.8). No swimming pools or water features were found.


132

Figure 5.8 Aerial view of low income houses in Samambaia

Source: Google Earth

5.3.5 Water fixtures and appliances in the home

Details over a number of water using fixtures and appliances used within dwellings

were gathered. These are major pieces of water using equipment within water

consuming areas of the home, and therefore, indicate water using activities per dwelling

amenity, as well as the capacity of a home to use water on a regular basis.

The number of water fixtures and appliances was collected through the use of the

quantitative face-to-face questionnaire survey, whilst their flow-rates were measured

during the in-depth water auditing approach. Table 5.4 summarizes the average number

and flow rates of water fixtures and appliances for the different levels of income.

Results from the questionnaires and water audit inventories also demonstrated that the

quantity and quality of these equipments are directly related to household income and

dwelling typology. High income dwellings contained the highest number of water

fixtures and appliances, while low income dwellings had the lowest number of water

using equipment. It was observed that the higher the income, the higher the quality of

water fixtures and appliances were within dwellings. The quality and quantity of water

fixtures and appliances were evaluated according to water using amenities within a

dwelling.


133

Overall, mid-high income dwellings presented higher flow rates within their fixtures.

This was probably due to its multi-storey typological characteristic, where water was

indirectly fed to flats through a mains water tank positioned above the building’s last

floor, causing an increase in water pressure while supplying water to the different

floors, resulting in slightly higher fixture flow rate figures.

On the other hand, low income dwellings demonstrated lower flow rate figures within

their water fixtures. This might be explained by the way in which low income residents

operated their water fixtures. Some low income residents which took part in the flow

rate measurements during the water audit inventory demonstrated a low consumption

tap-opening habit. When they were asked to demonstrate how they usually operated a

tap-opening fixture, these residents opened their taps by less than a half turn, resulting

in lower flow rate averages.

Table 5.4 Average flow rates and number of water fixtures and appliances

Water End-Uses High Income Mid-High Income Mid-Low Income Low Income

No. Flow Rate No. Flow Rate No. Flow Rate No. Flow Rate

Lavatory Faucet 6 4.8 l/min 3 6.7 l/min 3 5.1 l/min 2 4.9 l/min

Shower Head 5 5.4 l/min 3 5.7 l/min 2 5.2 l/min 2 4.0 l/min

Bath Faucet 1 8.3 l/min 0 --- 0 --- 0 ---

Bidet / Hand Douche 4 4.2 l/min 2 7.2 l/min 1 4.4 l/min 1 10.2 l/min

Toilet 6 9 l/flush 3 9 l/flush 3 9 l/flush 2 9 l/flush

Kitchen Faucet 2 6.0 l/min 1 6.8 l/min 1 5.4 l/min 1 4.7 l/min

Water Filter 1 2.4 l/min 1 2.2 l/min 1 2.5 l/min 1 2.5 l/min

Dishwasher 1 10.0 l/load 1 12.6 l/load 0 --- 0 ---

Laundry Sink Faucet 2 7.2 l/min 1 7.4 l/min 2 6.4 l/min 2 5.4 l/min

Washing Machine 1 141 l/load 1 164 l/load 1 155 l/load 1 164 l/load

External Tap 3 16.8 l/min 3 16.8 l/min 1 9.6 l/min 1 8.9 l/min

Swimming Pool Valve 1 16.8 l/min 0 --- 0 --- 0 ---

Swimming Shower Head 1 16.8 l/min 0 --- 0 --- 0 ---

5.3.5.1 Bathroom fixtures

Low income dwellings had in average 2 bathrooms per dwelling containing only the

necessary bathroom fixtures (toilet, shower head and lavatory faucet), while high

income dwellings had an average of 6 bathrooms per dwelling, containing extra

bathroom fixtures such as bath faucets and bidets or hand douches. Whilst most low

income dwellings contained plastic lavatory faucets with low budget toilets and shower

heads, high income dwellings had high standard bathroom fixtures, and some presented

state-of-the-art bathroom fixtures.


134

5.3.5.2 Kitchen fixtures and appliances

The majority of the high income dwellings had two kitchen faucets; one in the kitchen,

and another outside, within a barbeque area. Overall, the remaining income dwellings

did not have a barbeque area, and therefore, contained in average, one kitchen faucet per

home. From low budget plastic kitchen faucets to state-of-the-art equipments, it was

observed that the higher the dwelling income, the better the quality of fixtures and

appliances was. Many dwellings had water filter appliances in their home. Low income

households however, did not have such appliances.

5.3.5.3 Utility fixtures and appliances

Water using equipments such as the laundry sink, sink washers and washing machines

are commonly found in utility rooms. The laundry sink is generally used to hand-wash

floor cloths and delicate clothing by hand. Sink washers can be described as

mechanically driven laundry sinks. These non-automatic washing machines are low

budget laundry appliances used to pre-wash clothes. Different from washing machines,

the sink washer has to be drained manually after use.

While in average, high and mid-high income dwellings had one washing machine per

home and no sink washer most middle and low income dwellings had none. Over half

of mid-low and low income dwellings (55%), had both sink washer and washing

machine at their homes. In some cases, sink washers were used to pre-wash clothes

prior washing machine, but in others, the home simply updated from sink washers to

washing machines and kept both appliances.

Although it was quite common to find only one laundry sink per home, overall, house

dwellings demonstrated to contain two laundry sink faucets. The use of two laundry

sinks per dwelling might be explained through behavioural attitudes towards washing

clothes; while one laundry sink is filled with water for soaking clothes, the other is free

to be used. On the other hand, most of the interviewed flat dwellings, demonstrated to

have had only one laundry sink faucet due to lack of space.

5.3.5.4 External taps

Every house dwelling had at least one external tap for garden irrigation and floor

washing. High income dwellings contain larger garden areas, and therefore, presented a

larger number of external taps for irrigation. The majority of high income dwellings had


135

a swimming pool, and therefore, contained a pool shower head. It was uncommon to

find a swimming pool at the remaining income houses. Due to their built type, mid-

high income dwellings from Brasília and Águas Claras had no external taps or pool

shower heads. External taps were found within communal grounds of their residential

high-rise buildings, and no pool shower heads were found. Due to their typological

characteristics, the average flow rate and number of external taps considered for

analysis was for the entire residential building block.

5.4 Domestic water consumption

Primary data on baseline water consumption for the high, mid-high, mid-low and low

income dwellings were collected through the water auditing technique developed to

measure domestic water consumption using a technical survey linked with diary log

sheets and metered measurements in order to obtain annual, monthly, weekly and daily

consumption indicators as well as to understand water end-use consumption. Results

were analysed and performance evaluated.

5.4.1 Annual water consumption

Annual water consumption data for 117 dwellings, gathered from historic billing

records during the water auditing period, ranged from a minimum 36m3 per dwelling

per year to a maximum 732m3 per dwelling per year, and a mean 282m3 per dwelling

per year.

Figure 5.9 Average annual water consumption per dwelling

481

243216

180

0

100

200

300

400

500

600


(m3 /

dw

ellin

g)


136

It was observed that the higher the income, the higher the average annual water

consumption. Overall, high income house dwellings from Lago Norte and Lago Sul

presented the highest annual rate of consumption with an average 481m3 per annum.

Mid-high income flat dwellings from Brasília and Águas Claras presented an average

water consumption rate of 243m3/year, mid-low income house dwellings from

Taguatinga and Candangolândia 216m3/year and low income house dwellings from

Ceilândia and Samambaia 180m3/year (Figure 5.9).

5.4.2 Monthly water consumption

Monthly variations of mean water consumption throughout the year were analysed by

cross-referencing climatic data of monthly precipitation and relative humidity

(METEOTEST, 1999) with the historic billing data of the 117 dwellings studied. It was

observed that monthly water consumption had a direct relationship with monthly

precipitation and relative humidity, where the lower the precipitation and relative

humidity, the higher the water consumption, and the higher the precipitation and

relative humidity, the lower water consumption (Figures 5.10 and 5.11). This tendency

might be explained due to the Federal District’s intense dry season (from April to

September), which raises the demand of water for garden irrigation.

Figure 5.10 Average monthly water consumption and precipitation

0

50

100

150

200

250

300

0

5

10

15

20

25

30

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Av. Monthly Water Consumption (m3) Monthly Precipitation (mm)


137

Figure 5.11 Average monthly water consumption and relative humidity

Figure 5.12 Average monthly water consumption per income range

Figure 5.12 shows seasonal mean water consumption patterns per income range for the

analysed dwellings. A distinct high monthly water consumption pattern for high income

dwellings could be observed. Due to the fact that high income dwellings from Lago

Norte and Lago Sul contain large non-native vegetated garden areas (see Section 5.3.4),

they require higher amounts of water for irrigation during the Federal District’s dry

season. On the other hand, little seasonal variations of water consumption for mid-high,

mid-low and low income dwellings were observed. Brasília, Águas Claras, Taguatinga,

Candangolândia, Ceilândia and Samambaia dwellings require little or no water for

irrigation due to their typological characteristics.

0

10

20

30

40

50

60

70

80

90

0

5

10

15

20

25

30


Av. Monthly Water Consumption (m3) Relative Humidity (%)

0

5

10

15

20

25

30

35

40

45

50


(m3 /

dw

ellin

g)



138

5.4.3 Weekly water consumption

Weekly water consumption trends were obtained through daily monitoring of water

usage for the 117 audited dwellings during a seven day period. The average weekly

consumption for all of the studied sites ranged from a minimum 854 litres per dwelling

per week to a maximum 32,393 litres per dwelling per week, with a mean 5,191 litres

per dwelling per week.

Overall, high income house dwellings from Lago Norte and Lago Sul presented the

highest rate of weekly water consumption with an average 8,978 litres per week. Mid-

high income flat dwellings from Brasília and Águas Claras presented an average water

consumption rate of 4,412 litres per week, mid-low income house dwellings from

Taguatinga and Candangolândia 4,384 litres per week and low income house dwellings

from Ceilândia and Samambaia 3,378 litres per week.

Figure 5.13 summarises the weekly water consumption patterns for all audited

dwellings. The highest rates of consumption were during weekdays, ranging from 842

to 719 litres per dwelling per day, while water consumption on weekends ranged

between 687 and 637 litres per dwelling per day.

Figure 5.13 Average weekly water consumption patterns

Figure 5.14 shows weekly water consumption variations between the different income

dwellings. High, mid-low and low income house dwellings consumed higher amounts

of water during weekdays, while mid-high income flat dwellings consumed higher

amounts of water during the weekend.

0

100

200

300

400

500

600

700

800

900

Mon Tue Wed Thu Fri Sat Sun

(lit

res/

dw

ellin

g)


139

High income dwellings form Lago Norte and Lago Sul presented great variations of

daily water consumption during the week in comparison to other income ranges, with

higher consumption patterns during weekdays (mean 1,403 litres/day) and lower

consumption pattern during the weekend (mean 981 litres/day). This trend can be

explained by the oscillating number of residents at the dwelling during weekdays and

weekend. It is important to remember that most high income dwellings had gardeners

and housekeepers living at the household during weekdays; in the weekends, these

workers would return to their own homes, therefore playing a major influence over

water consumption.

Daily water consumption monitoring indicated that peak consumption during the week

was directly related with house cleaning. It was observed that during days on which

clothes and floors were washed, dwelling water consumption raised significantly.

Figure 5.14 Average weekly water consumption patterns per income range

5.4.4 Daily water consumption

Average daily water consumption was obtained from daily readings during water

auditing for each of the 117 analysed dwellings.

5.4.4.1 Water consumption per dwelling

Figure 5.15 shows that most dwellings consumed less than 1,000 litres per day, with a

mean daily consumption of 742 litres per dwelling per day. Mean daily water

0

200

400

600

800

1000

1200

1400

1600

1800

Mon Tue Wed Thu Fri Sat Sun

(lit

res/

dw

ellin

g)



140

consumption for most dwellings (42.2%) ranged between 501 – 1,000 litres/day, while

36.2% of the analysed dwellings consumed up to 500 litres/day and the remaining

21.6% presented an average daily consumption of over 1,000 litres/day.

Figure 5.15 Scatter diagram of average daily water consumption per dwelling

Overall, high income house dwellings from Lago Norte and Lago Sul presented the

highest rate of daily water consumption with an average 1,283 litres per day. Mid-high

income flat dwellings from Brasília and Águas Claras presented an average water

consumption rate of 630 litres per day, mid-low income house dwellings from

Taguatinga and Candangolândia 625 litres per day and low income house dwellings

from Ceilândia and Samambaia 483 litres per day.

5.4.4.2 Water consumption per capita

Figure 5.16 shows a scatter diagram of the water consumption per person per day for

the 117 audited dwellings. With a mean consumption of 196 litres per person per day,

most dwellings consumed less than 200 litres per person per day. Average per capita

water consumption for the majority of the analysed dwellings ranged between 101 – 200

litres per person per day (45.7%), while a small portion of the observations consumed

above 300 litres per person per day (8.6%), 18.1% consumed up to 100 litres per person

per day, and the mean per capita consumption for 27.6% of dwellings ranged between

201 – 300 litres.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 20 40 60 80 100 120

Av

. D

ail

y C

on

sum

pti

on

(li

tre

s/d

ay

)

Observations (n=117)


141

Figure 5.16 Scatter diagram of average daily water consumption per capita

Figure 5.17 clearly shows the direct relationship between water consumption per capita

and dwelling income range. With the highest per capita water consumption, high

income house dwellings from Lago Norte and Lago Sul consumed in average 321 litres

per person per day, mid-high income flat dwellings from Brasília and Águas Claras

mean water consumption rate was 205 litres per person per day, while mid-low income

house dwellings from Taguatinga and Candangolândia consumed an average 146 litres

per person per day, and with the lowest consumption rate, low income house dwellings

from Ceilândia and Samambaia per capita consumption was an average 112 litres per

person per day.

Figure 5.17 Average daily water consumption per capita by income range

0

200

400

600

800

1000

1200

0 20 40 60 80 100 120

Av

. C

on

sum

pti

on

pe

r C

ap

ita

(lit

res/

pe

rso

n/d

ay

)

Observations (n=117)

321

205

146

112

0

50

100

150

200

250

300

350


(lit

res/

per

son

/day

)


142

Previous studies (Loh and Coghlan, 2003; Thackray et al., 1978; Zhang and Brown,

2005) have indicated that the raise in domestic water consumption is constant and

proportional to the household income (see Chapter 2). Although the overall findings

were in-line with previous research, this study has shown that, not only domestic water

consumption increases proportionally to the increase in income, but also there was a

significant contrast of domestic water consumption for high income dwellings in the

Federal District. In short, there is an outstanding difference in water consumption of

high income dwellings when compared to lower income ranges (Figures 5.9; 5.12; and

5.17).

5.4.5 End-use consumption

End-use water consumption patterns for the 117 analysed dwellings were obtained

through daily measurements of end-use water usage during a seven day period. Figure

5.18 illustrates the average domestic water end-use consumption pattern for the Federal

District at its simplest form, including potable, laundry, toilet flush and outdoor uses.

Figure 5.18 Average domestic water end-use consumption pattern at its simplest form

To be able to compare the end-use results of this research with that of previous studies,

leaks and losses were not accounted. Swimming pool water end-use consumption was

also not included for comparison for two main reasons. The first, was that apart from

two studies (Loh and Coghlan, 2003; Roberts, 2005), the great majority of analysed

dwellings in previous research, did not have swimming pools. The second reason was

Potable Uses47%

Laundry25%

Toilet Flush15%

Outdoor uses13%


143

that a very small sample size of dwellings in the Federal District used water for topping-

up swimming pools (Table 5.6).

Although overall results from this study presented similar proportions of water end-use

consumption from previous studies carried out in developing countries (as seen in

Chapter 2, Section 2.4, Figure 2.12), the Federal District presented a slightly higher

trend in laundry water use. Such disparity might be related to differences in water-using

habits and utility fixtures and appliances. For a more in-depth analysis, disaggregated

results of domestic water end-use consumption were categorized according to indoor

water consumption and outdoor water consumption.

5.4.5.1 Indoor water consumption

With a total mean indoor consumption of 182 litres per person per day, in average,

indoor water-consuming activities from shower heads (20.6%), washing machines

(17.2%), toilet flushes (16.8%) and kitchen faucets (16.6%) had the highest rates of

daily water consumption per person, while water filters (1,4%), bidet/hand douches

(1,4%) and dishwashers (1,5%) contained the lowest rates of daily consumption per

person (Figure 5.19).

Figure 5.9 Average indoor water end-use consumption per capita

Although each individual dwelling demonstrated unique patterns of indoor water

consumption, similar trends were observed between the varied income groups and built

types. Table 5.5 summarises the results for the indoor water end-use consumption,

demonstrating a high consumption trend at the kitchen faucet, shower head and toilet

flush, and a low consumption trend at the water filter and bidet/hand douche for high,

Bathroom Faucet8.6%

Shower Head20.6%

Bidet / Hand Douche

1.5%Toilet Flush

16.8%Kitchen Faucet16.6%Water Filter

1.4%

Dishwasher1.8%

Utility Faucet9.5%

Washing Machine

17.2%

Leaks & Losses6.0%


144

mid-high, mid-low and low income dwellings. Overall, high income dwellings

presented the highest water end-use consumption rates, while low income dwellings had

the lowest water end-use consumption rates.

With the highest total mean indoor water consumption of 227 l/p/d (litres per person per

day), high income dwellings presented an end-use water consumption rate of 42 l/p/d on

toilet flushes (18.5%), 36 l/p/d on shower heads (15.9%) and 35 l/p/d on the kitchen

faucet (15.4%). Overall, 25.3% of indoor water consumption was used for clothes

washing and cleansing on washing machines (34 l/p/d) and utility faucets (23 l/p/d),

posing a significant contribution towards indoor water consumption. The lowest end-use

water consumption rates were measured at bidet/hand douches (1.1%) with an average

consumption rate of 2.6 l/p/d, water filters (1.4%) with a mean rate of 3.2 l/p/d and

dishwashers (2.3%) with an average consumption of 5 l/p/d. One out of seven analysed

house dwellings presented water leakage (11.9%), with an average loss rate of 27 l/p/d.

With a total average indoor consumption of 221 l/p/d, mid-high income dwellings

obtained their highest end-use water consumption values on shower heads (23.9%) with

an average 53 l/p/d, washing machines (22.1%) with an estimated 49 litres/person/day,

toilet flushes (15.8%) with a mean 35 litres/person/day and kitchen faucets (15.5%)

with a mean rate of 34 l/p/d. Low end-use rates were measured on dishwashers (0.7%)

with a mean 1 l/p/d, water filter (1.3%) with an estimated 3 l/p/d and bidets / hand

douches (1.5%) with an average 3 l/p/d, indicated that such appliances and fixtures were

not commonly used. It was observed that, due to periodic maintenance of building

hydraulics, no visible leaks were detected on the analysed flat dwellings.

Mid-low income dwellings, on the other hand, had an average indoor water

consumption of 144 l/p/d. Their highest mean end-use water consumption rates were 33

l/p/d on shower heads (23.0%), 29 l/p/d on kitchen faucets (20.2%) and 27 l/p/d on

toilet flushes (19%) with low mean rates of 2 l/p/d on water filters (1.4%), 4 l/p/d on

bidet/hand douches (2.8%) and 10 l/p/d on bathroom faucets. From 28 analysed

dwellings, only 6 contained hand douches, and none of them presented a dishwasher.

Only one mid-low income house presented leakage of an estimated 0.5 l/p/d (0.3%).

Low-income dwellings presented the lowest indoor water consumption with an average

total of 118 litres per person per day. The highest rates were measured at shower heads


145

(23.7%) with a mean 28 l/p/d, kitchen faucets (18.9%) with average 22 l /p /d and toilet

flushes (16.0%) at 19 l/p/d. The lowest end-use values were registered on bidets/hand

douches (0.8%) with a low rate of 1l/p/d, water filter (1.8%) with a low average of 2

l/p/d and utility faucets (8.8%) with a mean 10 l/p/d. From a total of 26 analysed

dwellings, only 3 low income dwellings had hand douches and none of them contained

a dishwasher. Five low income dwellings presented leaks (4.3%) with an average water

loss rate of 5 l/p/d.

5.4.5.2 Outdoor water consumption

Overall, water consumption from external taps consisted mainly of garden irrigation and

floor washing. Therefore, irrigable garden areas, as well as veranda, paved yards and

other washable floor areas were considered as a basis for parametrical comparison of

external water consumption. In this study, garden/floor area was equivalent to irrigable

garden areas and washable floor areas such as verandas and paved yards. These were

identified through resident interview and measured on site. Due to its building typology,

outdoor water consumption for high rise residential building blocks were performed

within communal grounds, and therefore considered for benchmarking consumption.

Both irrigation and floor washing water consumption were estimated as a whole, due to

the fact that both activities use the same water fixture or alternative source of water

supply.

Table 5.6 summarises the results of outdoor water consumption for garden irrigation

and floor washing. High income dwellings from Lago Norte and Lago Sul had the

highest water consumption rate of 2.2 litres per garden/floor area per day, while mid-

low and low income house dwellings had an average 0.7 l/m2/d. With the lowest water

consumption rate of 0.5 litres per garden/floor area per day (l/m2/d), high rise flat

buildings from Brasília and Águas Claras, consumed 42% less water than house

dwellings. Such results are compatible with findings presented by Loh and Coghlan

(2003), which indicated that multi-storey flat buildings consumed 55% less water

outdoors than house dwellings (see Chapter 2, section 2.4.1).

From twenty eight high income house dwellings with a swimming pool, only four

dwellings topped-up their swimming pools with mains water during water auditing.

Overall, swimming pools had a high water consumption rate (9 litres per swimming

pool area per day), and therefore, the great majority of dwellings avoided mains water


146

top-ups or used a closed filtration system for water purification, avoiding water losses

for cleansing. During water auditing, no water consumption was measured from

swimming pool shower heads, therefore, it was not included for analysis.

Lago Norte and Lago Sul house dwellings situated near the lake normally have access to

groundwater. A small sample size of dwellings extracted groundwater from wells in

order to use on irrigation and floor washing (0.8 l/m2/d). The remaining administrative

regions did not have access to groundwater tables.

This study represents the first attempt to understand outdoor water end-uses in Brazilian

dwellings. Works carried out so far have focused in analysing indoor water end-use

consumption, and no attention has been given to outdoor end-uses such as irrigation,

floor washing and swimming pool top-up (see Chapter 2 Section 2.4).


147

Table 5.5 Indoor water end-use consumption per income range

Indoor Water End-Uses High Income Mid-High Income Mid-Low Income Low Income

l/p/d*

sample size % l/p/d* sample size % l/p/d

* sample size % l/p/d

* sample size %

Bathroom Faucet 18 28 8.1 21 35 9.5 10 28 7.1 13 26 10.9

Shower Head 36 28 15.9 53 35 23.9 33 28 23.0 28 26 23.7

Bidet / Hand Douche 3 19 1.1 3 23 1.5 4 6 2.8 1 3 0,8

Toilet Flush 42 28 18.5 35 35 15.8 27 28 18.6 19 26 16.0

Kitchen Faucet 35 28 15.4 34 35 15.5 29 28 20.2 22 26 18.9

Water Filter 3 22 1.4 3 21 1.3 2 14 1.4 2 8 1.8

Dishwasher 5 2 2.3 1 5 0.7 --- --- --- --- --- ---

Utility Faucet 23 28 10.2 22 33 9.8 14 28 9.7 10 23 8.8

Washing Machine 34 28 15.1 49 32 22.1 25 22 17.1 17 18 14.7

Leaks & Losses 27 4 11.9 --- --- --- 0.5 1 0.3 5 6 4.3

TOTAL 226 100.0 221 100.0 144 100.0 118 100.0 *litres per person per day

Table 5.6 Outdoor water end-use consumption per income range

Water Sources High Income Mid-High Income Mid-Low Income Low Income

l/m2/d

* sample size l/m

2/d

* sample size l/m

2/d

* sample size l/m

2/d

* sample size

External Tap 2.2 25 0.5 30 0.7 22 0.7 17

Swimming Pool Valve 9 4 --- --- --- --- --- ---

Water Well 0.8 2 --- --- --- --- --- ---

Water Reuse 1.3 1 --- --- 1.5 11 2.0 13 *litres per garden, floor or swimming pool area per day


148

5.5 Water end-use frequencies and activities

In order to understand the behavioural aspects of domestic water usage for the different

income dwellings, primary data on resident’s frequencies of water usage per water

fixture and appliance, as well as their main water-consuming activities were collected

during the water auditing survey.

5.5.1 Frequencies of water usage

As seen in Chapter 4, end-use water consumption frequencies for tap-opening fixtures

were determined by dividing average daily water consumption with their average

measured flow rates, while water consumption frequencies for appliances were obtained

by the product of their average daily water consumption with their fixed water

consumption rate per usage. Average values of water consumption frequencies for the

various end-uses from high, mid-high, mid-low and low income dwellings were

obtained (Table 5.7).

Table 5.7 End-use water consumption frequency per income range

Water End-Uses High Income Mid-High

Income

Mid-Low

Income Low Income Average

Lavatory Faucet 3.8 min/p/d 3.1 min/p/d 2.0 min/p/d 2.6 min/p/d 2.9min/p/d

Shower Head 6.7 min/p/d 9.2 min/p/d 6.3 min/p/d 7.0 min/p/d 7.3 min/p/d

Bidet / Hand Douche 0.6 min/p/d 0.5 min/p/d 0.9 min/p/d 0.1 min/p/d 0.5 min/p/d

Toilet 5 f/p/d 4 f/p/d 3 f/p/d 2 f/p/d 4 f/p/d

Kitchen Faucet 5.8 min/p/d 5.1 min/p/d 5.4 min/p/d 4.7 min/p/d 5.2 min/p/d

Water Filter 1.3 min/p/d 1.2 min/p/d 0.8 min/p/d 0.9 min/p/d 1.1 min/p/d

Dishwasher 0.5 load/p/d --- --- --- --

Laundry Sink Faucet 3.2 min/p/d 2.9 min/p/d 2.2 min/p/d 1.9 min/p/d 2.6 min/p/d

Washing Machine 0.2 load/p/d 0.3 load/p/d 0.2 load/p/d 0.1 load/p/d 0.2load/p/d

External Tap 0.1 min/m2/d 0.03 min/m

2/d 0.1 min/m

2/d 0.08 min/m

2/d 0.1 min

2/d

Swimming Pool Valve 0.7 min/m2/d --- --- --- --

min/p/d – minutes per person per day f/p/d – flush per person per day load/p/d – load per person per day

Results indicated that, in average, lavatory faucets were used on a frequency of 2.9

minutes per person per day (min/p/d), daily showers lasted 7.3 minutes per person,

bidets or hand douches were used for only 0.5 min/p/d, toilets were flushed 3.5 times a

day per resident, the kitchen faucet was used for 5.2 min/p/d, the water filter was used

for 1.1 min/p/d for drinking purposes, the laundry sink faucet was used 2.6 min/p/d, 0.2

loads of dirty clothes were washed per day, and the external tap used to wash floors or

irrigate gardens for 0.1 minutes per garden/yard area per day (min/m2/d).


149

Although the average results of water end-use frequencies were similar to the average

values obtained from previous studies (see Chapter 2, Section 2.4.3), some differences

in the patterns of water end-use frequencies could be observed.

Interestingly, the average results of indoor faucet frequency were similar to those

studies carried out in developed countries, rather than from previous findings in Brazil

(Ghisi and Ferreira, 2007; Ghisi and Oliveira, 2007). Although frequencies of bathroom

faucet usage were within range of previous findings in Brazil, the duration of kitchen

faucet usage frequency was almost twice as high. Such differences might be explained

through the methodological approach used by previous studies for estimating water end-

uses, or even, by their limited number of samples collected.

Mid-low and low income dwellings presented lower rates of toilet usage per capita than

those from previous studies. This might be related to resident occupancy patterns inside

the home, which in turn, could be related to employment patterns and working hours.

Clearly, as the dwelling income level rose, so did the number of toilet flushes per capita.

Although both high and mid-high income dwellings contained dishwashers in their

homes, only high income dwellings used it, at an estimated frequency of 0.5 loads per

person per day (load/p/d), during water auditing. High income dwellings also presented

an average water consumption frequency of 0.7 minutes per swimming pool area per

day (min/m2/d) at the swimming pool valve for water top-up.

The fact that no water consumption in bath faucets and swimming pool shower heads

was registered in high income dwellings during water auditing does not mean that these

fixtures are not used by residents. Their sole existence in dwellings indicates that some

usage must occur. However, results do indicate that these fixtures are rarely used and

they do not affect domestic water consumption.

In general, high income dwellings presented the highest frequency rates of water end-

uses, whilst low income dwellings had the lowest end-use water consumption frequency

rates. One hypothesis is that dwelling income and occupant perception on the cost of

water can influence water consumption frequencies through behavioural attitudes.


150

Although the results above provided some useful information regarding domestic water

consumption behaviour for the different income dwellings, through patterns of water

consumption frequency for the different end-uses, it fails to provide a better

understanding on how water is used and what types of equipments are involved.

5.5.2 Water-consuming activities

An in-depth analysis of water-consuming activities inside 117 dwellings was carried out

in order to provide some understanding on the behavioural patterns of domestic water

usage for the different income dwellings. Key elements of water usage such as dish

washing, clothes washing, vehicle washing, floor washing, garden irrigation, water

reuse and water-saving attitudes were measured in order to point out behavioural trends

of water consumption according to dwelling income range and built type.

5.5.2.1 Dish washing

Residents were asked about their use of water for washing dishes. Overall, most

respondents washed their dishes at least twice a day (33.4%), 26.1% washed three times

a day, and some, more than three times a day (21.3%). The remaining 19.2% washed

their dishes less than twice a day. Mid-low income dwellings were more likely to wash

their dishes three times a day, while the other income groups usually washed their

dishes twice a day.

Most residents washed their dishes by hands, controlling the faucet (opening and

closing) while washing (83.5%). Some residents, however, washed their dishes with

running water at all times, with the faucet constantly opened (11.6%). No respondent

washed their dishes with a plugged sink, different from other findings, where a clear

majority of residents washed their dishes using a plugged sink (Randolph and Troy,

2008). Such behavioural differences in dish washing could be linked to cultural values,

custom and tradition.

A small number of respondents washed their dishes using a dishwasher (4.9%). Similar

findings were reported in Randolph and Troy (2008) indicating that those who have a

dishwasher, barely use them.

But for those residents which made use of dishwashers, few of them used economy

settings (14.5%), the great majority did not use economy settings (69.3%) and the


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remaining 16.3% did not have economy settings on their dishwashers. Low income

dwellings were less likely to use economy settings.

5.5.2.2 Clothes washing

Residents were asked about the use of water for washing clothes. High and mid-high

income dwellings washed their clothes more frequently than mid-low and low income

dwellings. With clothes washing frequencies reaching up to more than once a day, most

high income dwellings (27.3%) and mid-high income dwellings (28.1%) washed their

clothes in an average of three times a week. On the other hand, mid-low income

dwellings (35.0%) and low income dwellings (46.7%) were most likely to wash their

clothes only once a week.

The great majority of respondents (53.6%) washed part of their clothes by hands, the

remaining was machine-washed. While 25.3% of residents machine-washed their

clothes without pre-wash, 13.0% pre-washed their delicates and white clothes in the

washing machine. A few low-income dwellings washed their clothes by hands only

(11.1%), indicating that these families cannot afford a washing machine.

Findings suggest, however, that washing part of the clothes by hand or pre-washing

delicates is a common practice amongst Brazilian households. Once more, such

behavioural pattern might be linked to cultural values custom and tradition, since

previous findings in a developed country reported that almost all respondents only used

washing machines at home (Randolph and Troy, 2008).

Most respondents from high income dwellings (52.2%) and mid-high income dwellings

(34.8%) used economy settings to machine-wash their clothes, while most residents

from mid-low income dwellings (81.8%) and low income dwellings (50.0%), did not

use economy settings to machine-wash their clothes. In average, 9% of all respondents

did not have a washing machine or sink washer with economy settings.

5.5.2.3 Vehicle washing

Residents were asked if they washed their vehicles at home. Overall, the great majority

of residents did not wash their cars at home (51.2%). No mid-high income flat dwelling

resident washed their car at home, due to condominium rules, and therefore, residents

are not allowed to have access to external water taps on communal grounds for car

washing.


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Most of the 48.8% of respondents used a hand-held hose for vehicle-washing at home.

Some residents used an automatic shutoff nozzle at the end of the hose to control water

flow during vehicle-washing (46.5%), others did not (39.8%). A small percentage of

residents (13.7%) used water buckets to wash their vehicles. It was observed, however,

that almost no resident washed their vehicles during the one-week water auditing

period, indicating that this was not a frequent activity.

5.5.2.4 Floor washing

In Brazil, it is a common habit to clean external grounds of homes, such as verandas,

yards, pavements and any other external surrounding paved floor surface. House

dwelling residents and residential building block facilities managers were asked about

their water usage on floor washing.

Overall, high income house dwellings from Lago Norte and Lago Sul, wash the external

grounds of their homes once a week (54.2%), while mid-low income houses from

Taguatinga and Candangolândia, in average, wash their external grounds more than

once a week (65.2%) and low-income houses from Ceilândia and Samambaia wash

their external floors in an average once a week (47.4%).

Most house dwellings from Lago Norte and Lago Sul (30.4%) and mid-low income

dwellings from Taguatinga and Candangolândia (45.0%) used a hand-held hose

without a shutoff nozzle to clean their floors, while 55.6% of low income house

dwellings from Ceilândia and Samambaia used a bucket of water and mop to wash their

external grounds.

As for residential building blocks from Brasília and Águas Claras, communal floors

were washed, in an average, once a week (41.7%) using hand-held hoses with automatic

shutoff nozzles (37.1%).

5.5.2.5 Garden irrigation

House dwelling residents and residential building block facilities managers were asked

often lawns were irrigated during the dry season (April – September) and rainy season

(October – March) and the type of irrigation equipment was used.


153

High income houses from Lago Norte and Lago Sul irrigated a small part of their lawn

(50.0%) more than once a week during the dry season (47.8%) using a hand-held hose

without a shutoff nozzle (47.1%). During the rainy season, the great majority of

residents did not irrigate their lawns (82.6%).

While 32.4 % of mid-high income residential building blocks from Brasília and Águas

Claras did not irrigate their communal gardens all year round, 38.2% irrigated their

lawns using a manual sprinkler system (52.2%). During the rainy season, 90.9% of the

communal gardens were rain-fed only.

While most mid-low income houses from Taguatinga and Candangolândia irrigated

their lawns during the dry season, one third of respondents did not use water to irrigate

their lawns all year round. In average, 33.3% of respondents watered their entire lawn

once a day during the dry season using a hand-held hose without a shutoff nozzle

(60.0%). During rainy season, most residents did not use water to irrigate their lawns

(62.5%).

Most low income house residents from Ceilândia and Samambaia irrigated their entire

lawn (75.0%), once a week during the dry season (46.2%), using a hand-held hose with

an automatic shutoff nozzle (41.7%). During the rainy season, 69.2% of respondents did

not water their lawns.

5.5.2.6 Water reuse

Residents were asked if they reused rainwater, greywater or wastewater in their homes.

From the analysed dwellings, 29.4% made use of rainwater and 36.8% made use of

greywater in their homes. No dwelling made use of reclaimed wastewater.

Three out of four low income residents used rainwater (40.0%) or greywater (60.0%) in

their homes for washing external floors. One in four dwellings made use of both

rainwater and greywater. Most dwellings used simple and low-budget directly fed,

untreated rainwater or greywater reuse systems. Most dwellings which made use of

rainwater, collected runoff from their rooftops and stored it on a 200 – 300 litres barrel

placed under gutters or downpipes for reuse on external floor washing. In one case, a

dwelling used rainwater for drinking purposes, by placing the collected rainwater into

the dwelling’s water filter. Most dwellings which made use of greywater, stored laundry


154

water from washing machines on 200 – 300 litres butts, and was usually used on the

same day for washing the external floors of the house. Residents used the first rinse of

the washing machine (which contains a considerable amount of soap) to scrub the

external floors, and the second rinse (with a cleaner water) to wash away the soap.

One in six mid-low income houses used rainwater (28.6%) or greywater (45.5%) mainly

for washing external floors by using the same low-budget directly fed untreated

rainwater and greywater systems described above. In some cases, rainwater and

greywater from the washing machine were used for pre-washing clothes.

One in eight high income house residents used rainwater (21.7%) or greywater (4.3%)

in their homes using simple directly fed systems. With little investment, some houses

used a simple pipework to transport untreated rainwater directly to swimming pools,

other houses stored rainwater inside water tanks for later use on gravity fed, sub-surface

irrigation of gardens. Using the same principal, one refurbished dwelling adapted its

plumbing in order to transport greywater from showers and bathroom faucets via

gravity to a sub-surface irrigation system.

No analysed residential building blocks from Brasília and Águas Claras made use of a

water reuse system.

Rainwater and greywater reuse were commonly used in low income house dwellings

(2.0 l/m2/d ) and mid-low income house dwellings (1.5 l/m2/d), however only one high

income dwelling reused water for irrigation and floor washing (1.3 l/m2/d), suggesting

that the lower the income, the higher the rate of water reuse. This suggests that due to

the cost of mains water, mid-low and low income households searched for alternative

sources of water to reduce water bills.

These results indicate that there was a direct relationship between mains water

consumption and water reuse, where, water reuse was inversely proportional to mains

water consumption. The lower the household income, the lower mains water

consumption was, however, the higher the usage of alternative water supply such as

rainwater and greywater reuse.


155

5.6 Water-saving attitudes in the home

In order to understand behavioural aspects of water-saving attitudes in the home,

residents were asked if they have taken any actions in the past to reduce water

consumption, and what actions they would be willing to take in order to promote water

conservation.

Figure 5.20 shows that although most high (63.6%), mid-high (58.4%) and low income

(60.0%) respondents had taken some type of water-saving action to reduce water

consumption in the last years, the majority of mid-low income residents took no actions

to conserve water (57.1%).

Figure 5.20 In the last years, has your dwelling taken any actions to conserve water?

Most of those residents, who, in the last years took actions to conserve water, made

changes in their water use habits (Figure 5.21). Personal water use habits such as taking

shorter showers or controlling water faucets while brushing teeth, shaving and washing

(29.7%), clothes washing (20.8%), dish washing and floor washing (16.8%) were the

most common actions taken by respondents.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%


Yes No


156

Figure 5.21 Actions residents have taken in the last years to conserve water at home.

More than 20% of residents of high income dwellings changed their habits regarding the

use of water. Considerable number of mid-high income residents changed their habits of

personal and dish washing water uses. Around 20% o mid-low and low income

residents changed their habits of personal and clothes washing water uses.

Regarding to actions taken to conserve water, a reasonable number of high income

dwellings had made changes in their habits of garden irrigation (25.0%), while the other

income dwellings had not (Table 5.8). In the last years, some high income residents

have made investments in water efficient fixtures, fittings or appliances (12.5%) and in

rainwater harvesting systems (16.7%), while little or no investments in this area have

been made for the other income dwellings. A great number of mid-high (21.2%) and

mid-low (16.7%) income residents repaired leakage in their homes, whilst only few

high (8.3%) and low (5.0%) income residents repaired water leaks in their homes.

Clearly, Figure 5.22 shows that most respondents willing to make changes in order to

reduce their domestic water consumption, are most likely to invest in water efficient

fittings, fixtures and appliances (47.5%), rainwater (39.6%) and greywater (27.7%)

reuse systems, as well as promoting changes in the habits of floor washing (26.7%) in

their homes.

0.0% 5.0% 10.0% 15.0% 20.0% 25.0% 30.0% 35.0%

Change in habits of personal water use

Change in habits of clothes washing

Change in habits of dish washing

Change in habits of vehicle washing

Change in habits of floor washing

Change in habits of garden irrigation

Water efficient equipment/tecniques for …

Leak repair

Installation of water efficient FFA

Installation of RWH system

Installation of GWR system

Installation of WWR system


157

Table 5.8 Actions taken in the last years to conserve water per income group

Water-saving attitudes HI MHI MLI LI

Change in habits of personal water use 29.2% 45.5% 16.7% 20.0%

Change in habits of clothes washing 16.7% 18.2% 20.8% 30.0%

Change in habits of dish washing 20.8% 33.3% 8.3% 5.0%

Change in habits of vehicle washing 20.8% 6.1% 8.3% 5.0%

Change in habits of floor washing 16.7% 15.2% 16.7% 20.0%

Change in habits of garden irrigation 25.0% --- 0.0% 5.0%

Water efficient equipment/techniques for irrigation 8.3% --- 4.2% 0.0%

Leak repair 8.3% 21.2% 16.7% 5.0%

Installation of water efficient FFA 12.5% 3.0% 0.0% 5.0%

Installation of RWH system 16.7% --- 0.0% 0.0%

Installation of GWR system 4.2% --- 0.0% 0.0%

Installation of WWR system 0.0% --- 0.0% 0.0%

FFA – Fittings, fixtures and appliances RWH – Rainwater harvesting GWR – Greywater recycling WWR – Wastewater reclamation

Figure 5.22 Actions residents are willing to take in order to conserve water at home

Most low income residents would rather change their water-consuming habits than

invest on water-saving equipments, while mid-low income residents are not only willing

to change their habits of water consumption, but also invest on water efficient fittings

fixtures and appliances and rainwater and greywater reuse systems. High income

residents, on the other hand, are not only willing to invest on rainwater and greywater

reuse systems, but also willing to change indirect water-using habits from gardeners or

housekeepers such as of clothes washing, floor washing and garden irrigation (Table

5.9).

15.8%

23.8%

24.8%

17.8%

26.7%

12.9%

17.8%

14.9%

47.5%

39.6%

27.7%

14.9%

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%

Change in habits of personal water use

Change in habits of clothes washing

Change in habits of dish washing

Change in habits of vehicle washing

Change in habits of floor washing

Change in habits of garden irrigation

Water efficient equipment/tecniques for …

Leak repair

Installation of water efficient FFA

Installation of RWH system

Installation of GWR system

Installation of WWR system


158

Table 5.9 Actions residents are willing to take in order to reduce water consumption

Water-saving attitudes HI MHI MLI LI

Change in habits of personal water use 4.2% 6.1% 29.2% 30.0%

Change in habits of clothes washing 33.3% 21.2% 16.7% 25.0%

Change in habits of dish washing 25.0% 24.2% 29.2% 20.0%

Change in habits of vehicle washing 20.8% 9.1% 25.0% 20.0%

Change in habits of floor washing 33.3% 21.2% 29.2% 25.0%

Change in habits of garden irrigation 25.0% --- 16.7% 15.0%

Water efficient equipment/techniques for irrigation 37.5% --- 29.2% 10.0%

Leak repair 29.2% 3.0% 16.7% 15.0%

Installation of water efficient FFA 58.3% 69.7% 33.3% 15.0%

Installation of RWH system 54.2% 48.5% 37.5% 10.0%

Installation of GWR system 29.2% 42.4% 25.0% 5.0%

Installation of WWR system 12.5% 30.3% 8.3% 0.0%

Interestingly, the great majority of mid-high income residents are most likely to invest

in water efficient equipments and water reuse systems, than to change their water-

consuming habits. A considerable number of flat residents would be willing to invest on

a communal wastewater reuse system (30.3%) whilst most house residents would be

unwilling to install such equipment in their homes. This might be due to the fact that

residential building blocks contain facility managers which can provide daily

inspections and periodic maintenance to wastewater reuse systems in order to avoid

health risks to residents, house dwellings on the other hand, do not.

In short, our research shows that not only a reasonable number of residents had taken

actions to change some habits of water use, but also they are willing to change another

habits and to install water efficient fittings and rain water and grey water systems.

5.7 Statistical evidence of water consumption

The scarcity of water resources is a crucial problem in the Federal District. Households

account for a great proportion of total water supply, and residential water demand has

become an important concern of policymakers. Demand for water increases due to: (i)

increase in population, (ii) economic growth, and (iii) life-style. The determination of

the variables that affect domestic water demand is an essential element for policy

makers decision.

As reviewed in Chapter 4, based on the hypothesis that domestic water consumption is a

function of dwelling income, number of residents, and building typology, a multivariate

statistical analysis was performed in order to explore the relationship between a series


159

of variables, evaluate their level of significance and model a domestic water function for

the Federal District.

So as to simplify the domestic water consumption models, only independent variables

with accessible data from secondary sources were selected. To evaluate the strength of

statistical correlation between the variables of indoor water consumption, outdoor water

consumption, number of residents, dwelling income, cost of water, built area and

garden/yard area, a matrix of simple correlations was carried out using Pearson

coefficient (the value of correlation does not depend on the specific units used).

The correlation coefficient is a measure of linear association between two variables and

it varies between 1 and 0. A correlation coefficient of 1 indicates that two variables are

perfectly related in a positive or negative linear sense. A correlation coefficient of 0

indicates that there is no linear relationship between the two variables. The correlations

serve as empirical indications of possible relationships between variables and measure

the degree of linear association between two variables.

Results shown in Table 5.10 indicates that indoor water consumption had a very strong

relationship with water tariff (0.90) and dwelling built area (0.63), a substantial

relationship with dwelling income (0.49) and a moderate relationship with the number

of residents (0.37). Outdoor water consumption on the other hand, presented a strong

relationship with garden/yard area (0.49) and a moderate relationship with dwelling

income (0.32). Dwelling income also had a substantial relationship with dwelling built

area (0.47) and garden/yard area (0.42). These correlation coefficients are significant at

the 1% or 5% level, that is, they are statistically significantly different from zero at 99%

or 95% level of significance.


160

Table 5.10 Matrix of simple correlations

Domestic Water

Consumption (m

3/month)

No. of Residents

Dwelling Income

(R$/month)

Cost of Water (R$/month)

Built Area (m

2)

Garden / Yard Area (m

2)

Outdoor Water Consumption (m

3/month)

Garden Water Cost

(R$/month)

Domestic Water Consumption (m

3/month)

Pearson Correlation 1 .365**

.489**

.905**

.632**

.190* .095 .132

Sig. (2-tailed) .000 .000 .000 .000 .048 .380 .220

N 119 119 111 119 117 108 88 88

No. of Residents

Pearson Correlation .365**

1 .032 .315**

.099 -.083 -.170 -.109

Sig. (2-tailed) .000 .742 .000 .289 .393 .114 .313

N 119 119 111 119 117 108 88 88

Dwelling Income (R$/month)


.032 1 .408**

.474**

.423**

.323**

.275*

Sig. (2-tailed) .000 .742 .000 .000 .000 .003 .011

N 111 111 111 111 109 103 84 84

Cost of Water (R$/month)


.315**

.408**

1 .475**

.184 .068 .081

Sig. (2-tailed) .000 .000 .000 .000 .057 .528 .452

N 119 119 111 119 117 108 88 88

Built Area (m

2)


.099 .474**

.475**

1 .326**

-.074 -.006

Sig. (2-tailed) .000 .289 .000 .000 .001 .495 .959

N 117 117 109 117 117 108 88 88

Garden / Yard Area (m

2)

Pearson Correlation .190* -.083 .423

** .184 .326

** 1 .491

** .357

**

Sig. (2-tailed) .048 .393 .000 .057 .001 .000 .001

N 108 108 103 108 108 108 87 87

Outdoor Water Consumption (m

3/month)

Pearson Correlation .095 -.170 .323**

.068 -.074 .491**

1 .937**

Sig. (2-tailed) .380 .114 .003 .528 .495 .000 .000

N 88 88 84 88 88 87 88 88

Garden Water Cost (R$/month)

Pearson Correlation .132 -.109 .275* .081 -.006 .357

** .937

** 1

Sig. (2-tailed) .220 .313 .011 .452 .959 .001 .000

N 88 88 84 88 88 87 88 88

**Correlation is significant at the 0.01 level (2-tailed).

*Correlation is significant at the 0.05 level (2-tailed).


161

However, correlation (association) does not prove causation. The correlation

coefficients cannot be interpreted as establishing cause-and-effect relationships.

Correlation is necessary but no sufficient for causation. In other words correlation

makes no assumption as to whether domestic water consumption variable is dependent

on the others, and is not concerned with the relationship between them.

Knowing that these variables are strongly associated with domestic water consumption,

a regression analysis was carried out in order to describe the level of dependence of

domestic water consumption from a series of independent variables. The most

commonly used form of regression is linear regression, and the most common type of

linear regression is called ordinary least squares regression.

Multiple regressions allowed the development of indoor and outdoor water consumption

models generating a prediction tool for domestic water consumption based on a set of

explanatory variables. So, the hypothesized relationship between water consumption

and number of residents, household income, cost of water, and built area may be written

as:

�� = zv + z2TV + zsn� + z{[ + z|lX + } (5.1)

Qd = Domestic Water Consumption �m3/month Nr = Number of Residents �person Id = Dwelling Income �R$/month Cw = Cost of Water �R$/month Ab = Built Area �m2 ε = Error in predicting the value of Q

The regression model in Equation 5.1 denotes the monthly indoor water consumption

for dwellings in Federal District as a function of number of residents, household income

(R$/month), cost of water (R$/month), and built area (m2). Due to the different units of

measurement between variables, the magnitudes of unstandardized coefficients were

difficult to assess. Standardized coefficients on the other hand, had a greater effect upon

the dependent variable of outdoor water consumption in the multiple regression

analysis. The magnitudes of Beta coefficients indicated which variables had the greatest

effect on the predicted value of indoor water consumption.


162

In multiple linear regression, the size of the coefficient for each independent variable

gives the size of the effect that variable is having on your dependent variable, and the

sign on the coefficient (positive or negative) gives the direction of the effect. The

coefficient tells how much the dependent variable is expected to increase when that

independent variable increases by one, holding all the other independent variables

constant.

The estimated regression (Equation 5.2) for indoor water consumption displayed a

relatively strong variation in function of number of residents, dwelling income, cost of

water and built area, with R2 = 0.881 p< 0.001. This value shows that 88.1% of the

variance in indoor water consumption can be predicted from the number of residents,

dwelling income, cost of water and built area.

F ratio is a test for statistical significance of the regression equation as a whole, i.e.

whether the equation as a whole is statistically significant in explaining water

consumption. The F statistics test the overall significance of the regression

model. Specifically, it tests the null hypothesis that all of the regression coefficients are

equal to zero.

Since F=192 is significant, the regression equation helps us to understand the

relationship between the water consumption and the other variables. Predictions from

this model are reliable and statistically significant at p=0.001 and F=192.446, with a

degree of freedom corresponding to 116. This provides evidence of existence of a linear

relationship between water consumption and the explanatory variables.

��x�ttV = 3.82 + 0.11TV + 0.09n� + 0.71[ + 0.24lX �5.2 �2.40 �3.19 �2.16 �5.79 �17.30 R2 = 0.88; F = 192.5 QIndoor = Indoor Water Consumption �m3/month Nr = Number of Residents �person Id = Dwelling Income �R$/month Cw = Cost of Water �R$/month Ab = Built Area �m2 In parenthesis, the value of t-statistics

The t-statistics is used to test the hypothesis that the true value of the coefficient is non-

zero. T-statistics is a measure of the likelihood that the actual value of the parameter is


163

not zero. The larger the absolute value of t, the less likely that the actual value of the

parameter could be zero. The t-statistics for the above independent variables and their

associated 2-tailed p-values indicated a reliability of p<0.033. The indoor water

consumption model indicates a constant value equivalent to 3.82, which suggests that

dwellings consume a minimum amount of 3.82 m3 of water per month, regardless of the

dwelling’s income, number of residents, cost of water and built area.

Our result shows, like other studies (Arbués et al., 2003; Barrett and Wallace, 2009;

Schleich and Hillenbrand, 2009) that household size is positively correlated with

domestic water consumption. Water demand is predicted to rise 0.11 m3/month for

every additional resident per dwelling. The estimated equation shows that dwelling

income has an influence over indoor water consumption, where, the higher the income,

the greater the consumption at 0.09 m3/month for every R$/month of income.

Also, our results indicate that the larger the dwelling, the higher the consumption at 0.24

m3/month per built area. Result similar to a series of studies that show that domestic

water consumption varies accordingly to residential buildings typology (Loh and

Coghlam, 2003; Russac et al., 1991; Zhang and Brown, 2005).

Although the cost of water was expected to be negatively related to domestic water

consumption, where, the higher the cost of water, the lower the consumption, the

estimated model indicates a positive relationship. This positive relationship is found in

numerous studies for other countries; they have shown that domestic water consumption

is price-inelastic (that is, an increase in the price of water does not reduces its

consumption) (Worthington and Hoffman, 2008).

Nauges and Whittinghton (2010) review what is known and what is missing from that

literature thus far that uses data from household surveys to estimate household water

demand functions in less developed countries. The findings from the literature on the

main determinants of water demand in these countries suggest that, despite

heterogeneity in places and time periods studied, authors agree on the inelasticity of

water demand in less developed countries.


164

This positive relationship might also be due to a low water tariff structure, where the

cost of water does not affect indoor water consumption negatively. Arbués et al. (2003)

argues that water demand is inelastic to water price since there are no substitutes for

water and because there is a low level of consumer perception on rate structures. On the

other hand, expenditure in water represents a very small fraction of household income

(Kostas and Chrisostomos, 2006 and Martinez, 2002).

The number of water facilities may help to explain the differences in water consumption

behaviour. Houses tend to have greater area, more bathrooms, gardens, and swimming

pool when compared to flat dwellings. So, we decided focus on outdoor domestic

consumption taking into account the garden and floor areas.

In most studies, outdoor water use is exclusively allocated to irrigation and swimming

pool consumption (Mayer et al., 1999). However, as far as the literature goes, no study

has analysed the influence of patios and verandas towards outdoor water consumption.

In Brazil, it is a common practice to wash patio and veranda floors periodically and

therefore, these outdoor spaces should be taken into consideration during domestic

water consumption analysis. This indicates that domestic water consumption is not only

associated with the number of persons in a household, but also with other communal

uses (i.e. irrigation, cleaning, washing, swimming pool, etc.).

Equation 5.3 presents the regression for monthly outdoor water consumption. The result

shows a near perfect relationship with garden/yard area and cost of water, with R2 =

0.906(116), p<0.001, indicating that 90.6% of the variance in outdoor water

consumption can be predicted from garden/yard area and cost of water. Predictions from

this model are reliable and statistically significant with p=0.000 and F=405.933, with a

degree of freedom corresponding to 116.

��ttV = 1.21 + 0.87[ + 0.18l�F (5.2) �2.58 �24.24 �5.02 R2 = 0.90 F = 405.9 QOutdoor = Outdoor Water Consumption �m3/month Cw= Cost of Water �R$/month Ag = Garden/Floor Area �m2 In parenthesis, the value of t-statistics


165

The result indicates that the cost of water has a greater effect on the predicted value of

outdoor water consumption than garden/floor area. T-statistics and their associated 2-

tailed p-values indicated a reliability of p<0.012.

The outdoor water consumption model indicates a constant value of 1.21, which

suggests that dwellings consume a minimum amount of 1.21 m3 of water per month for

garden irrigation and/or floor washing, regardless of the cost of water and garden/yard

area. The model also shows that outdoor water consumption is predicted to rise 0.18

m3/month for every m2 of garden/floor area. Although the cost of water was expected to

be negatively related to outdoor water consumption, our equation indicates that the

relationship is positive. This might be due to the fact that water tariff is low, and the

cost of water does not affect outdoor water consumption negatively, since water demand

is inelastic to water consumption. Moreover, there is no substitute for water, a low level

of consumer’s perception on water rates structure and the water tariff represents small

fraction of household income.

In order to verify the income inelasticity of water consumption hypothesis, residents

were asked to share their opinion over water tariffs. Although the great majority of

residents believed that the tariff charged by the water facility company was expensive,

their water-consuming behaviour indicated otherwise, especially with high income

dwellings. Such results indicate that resident’s perceived belief over the cost of water

was insufficient to modify water consumption behaviour.

Water demand in relatively price-inelastic, therefore price is an ineffective tool for

controlling its consumption. In this case non-price strategies would be more effective

for regulating water consumption like education campaigns (brochures and handouts,

television and radio, public broadcasting) and financial incentives to install water

efficient fittings, grey water reuse and rain water harvesting systems. These non-price

strategies intend to change behaviour since water does not appear on day-to-day agenda,

unless there is a crisis. Moreover, not only water is cheap but also there is a behavioural

inertia and an inability to modify residents behaviour.


166

5.8 Conclusion

This chapter explores the relationship between domestic water consumption and

residential dwelling typology, household income and occupant water use behaviour.

Findings suggest that dwelling characteristics affect not only domestic water

consumption, but also occupant behaviour.

Domestic water consumption was analysed at different levels, and overall, a direct

relationship between dwelling income and water consumption could be observed,

where, the higher the income, the higher the water consumption rate. High income

dwellings presented an average of 481 m3 per year, mid-high income flat dwellings an

average of 243 m3, mid-low income dwellings an average of 216 m3 and low income

dwellings an average of 180 m3 per year.

Average water consumption per person per day obtained from questionnaires presented

a mean of 196 litres per person per day. The consumption for the majority of dwellings

ranged from 101 to 200 litres per person per day. While high income dwellings

consumed above 300 litres per person per day, low income dwellings consumed an

average of 112 litres per person per day.

The quality and quantity of water fixtures and appliances were evaluated according to

water using facilities within a dwelling. It was observed that as household income rose,

so did the quality and quantity of water fixtures and appliances within dwellings.

Although each individual dwelling demonstrated unique patterns of indoor water

consumption, similar trends were observed between the varied income groups and built

types. The highest rates of water consumption per person per day comes from shower

heads (21%), washing machines and toilet flushes (17% each), and kitchen faucets

(16.6%).

Key elements of water usage such as dish washing, clothes washing, vehicle washing,

floor washing, garden irrigation, water reuse and water-saving attitudes was measured

in order to point out behavioural trends of water consumption according to dwelling

income range and built type.


167

The correlation analysis carried out shows a strong relationship between indoor water

consumption and built area (0.63), dwelling income (0.49), and number of residents

(0.37). Estimated water consumption function have shown a strong relationship between

dwelling income and built area. The coefficient of cost of water presented a positive

relationship showing that water demand is inelastic to water price due to the fact that

water tariff is low, there is no substitute for water, and water tariff represents a small

fraction of household income.

In order to verify the inelasticity of water of water consumption to its price, residents

were asked about their perception of water tariff. Although they believe that tariff is

high, observed water-consumption behaviour indicated otherwise. It seems that

resident’s opinion over water cost is insufficient to modify their behaviour. Our research

shows that the great majority of residents are most likely to invest in water efficient

equipments and water reuse systems rather than change their water-consuming

behaviour.

Chapter 6 Evaluation of Domestic


Evaluation of Domestic Water Conservation Measures

169

6. Evaluation of Domestic Water Conservation Measures

6.1 Introduction

In the previous chapter, primary data of household income, dwelling typology and

occupant behaviour was analysed and findings discussed. Based on such primary data,

this chapter sets out to identify feasible water conservation measures in terms of their

applicability, adaptability, water savings and cost-benefits, based on representative

models for the different income ranges and residential typologies of the Federal District.

6.2 Public Opinion, Awareness and Acceptance

In order to evaluate the applicability of water conservation measures for the different

income groups, 481 questionnaires were directed to residents, in order to understand

public opinion, awareness and acceptance over water conservation measures for the

varied income ranges.

6.2.1 Mains Water Metering and Tariff

Although every house contained an individual mains water meter, only few flats

dwellings were individually metered (11.1%). From those residential buildings which

were not sub-metered, 61.8% has plans to achieve sub-metering through plumbing

adaptation and building refurbishment. The great majority (90.4%) of residents were in

favour of installing individual mains meters in their flats.

Most of the residential flat buildings of Brasília and Águas Claras contained only one

mains water meter (88.9%), but one out of nine residential flat buildings had two mains

water meter; one shared between every flat dwelling, and the other for external use on

communal grounds. Due to the fact that external uses such as irrigation and floor

washing do not produce sewage to be collected and treated, water tariffs for external

uses were cheaper than for internal uses. However, few residential flat buildings

installed an extra water meter to measure external uses only in order to reduce water

cost.

In the Federal District, domestic water consumption is charged according to levels of

consumption, where, the higher the consumption range, the higher the water tariff per


170

m3 (Table 6.1). If a dwelling’s consumption is below 10m3/month, there is a minimum

monthly charge of R$14.30 (£4.08) for mains water supply maintenance and

administration, equivalent to 10m3 of mains water consumption. The facility company

also charges an extra tariff for sewage collection and treatment, with the same value of

water supply, doubling the cost of the water bill, arguing that the same volume of water

that comes in comes out as swage.

Table 6.1 Domestic water tariffs per consumption ranges

Consumption

Range (m3)

Range Volume (m

3)

Water Tariff Cost per Range Cumulative Cost

(R$/m3) (£/m

3) (R$) (£) (R$) (£)

0 to 10 10 1.45 0.41 14.30 4.09 14.30 4.09

11 to 15 5 2.66 0.76 13.30 3.80 27.60 7.89

16 to 25 10 3.39 0.97 33.90 9.69 61.50 17.58

26 to 35 10 5.47 1.56 54.70 15.63 117.20 33.21

36 to 50 15 6.04 1.73 90.60 25.89 206.80 59.10

More than 50 --- 6.61 1.89 --- --- --- ---

Source: Obtained from water consumption bills.

6.2.2 Monthly Water Bill

The questionnaires provided primary data over the average costs of monthly water bill.

Figure 6.1 shows that the higher the dwelling’s income, the higher the average monthly

water bill. Low income residents from Ceilândia and Samambaia paid, in average,

R$63.30 (£18.08) per month for their water consumption, while high income dwellings

from Lago Norte and Lago Sul paid, in average, R$213.72 (£61.06) per month.

Figure 6.1 Average dwelling monthly water bill per income group

R$ 213.72

R$ 105.05R$ 91.79

R$ 63.30

R$ 0.00

R$ 50.00

R$ 100.00

R$ 150.00

R$ 200.00

R$ 250.00



171

Through the use of questionnaires, residents were asked to share their opinion over

water tariffs (Figure 6.2). Overall, the majority of high, mid-low and low income

residents believed that the tariff charged by the water facility company was expensive

(66.4%), while 29.5% agreed with the tariff charged, and only 4.1% thought that the

tariff being charged was cheap. Mid-high income, most of them flat residents, did not

share the same opinion. They believe that the water tariff charged by the facility

company is cheap (32.7%), while 20.2% think that it is expensive, and only 4.8% agree

with the tariff.

Figure 6.2 Resident’s opinion on the costs of mains water

Overall, the majority of high rise flat residents did not have access to the building’s

monthly water bills, and therefore, were unaware of how much water they consumed

and how much was being charged for their water.

The majority of mid-high, mid-low and low income residents believed that the

progressive tariff over consumption ranges encourage consumers to control their water

consumption; however, 54.1% of high-income residents believed that such strategy does

not work (Figure 6.3).

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%


Expensive Fair Cheap Do not have acess to water bill


172

Figure 6.3 Incentive for water consumption reductions through progressive tariff

Apart from the progressive mains water tariff charges, residents were asked what they

thought about having an extra tariff charged for those dwellings whose water

consumption was way above average. Interestingly, although most respondents believed

water tariffs were high, the majority of the interviewed residents would agree to have an

extra tariff for high water usage as a way of promoting water conservation (Figure 6.4).

Figure 6.4 Resident’s opinion for charging an extra tariff for dwellings with

consumption above average

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

High Income Mid-High Income Mid- Low Income Low Income

Yes No Don't Know

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Yes No Don't Know


173

On the other hand, most respondents thought that it would be a good idea to have

financial incentives or bonuses for those dwellings whose water consumption was

below average (Figure 6.5). Residents whose water consumption was below

10m3/month, thought it was unfair to be charged the equivalent to 10m3 of mains water

consumption for their water bill. They believed that such charging does not incentive

residents to reduce their water consumption and to invest on water conservation

strategies.

Figure 6.5 Residents’ opinion for providing discounts for dwellings with consumption

below average.

Opinions were divided on the question whether an additional tariff destined towards

investments on water conservation practices and policies should be charged on water

bills. While most mid-high and low income dwellings agreed on an additional tariff

destined for water conservation improvements, high and mid-low income dwellings

disagreed (Figure 6.6).

Respondents, who disagreed to such additional cost over their water bills, believed that

the water tariff is already high enough for such investments to take place by the facility

company. From those who did agree with an additional water tariff to fund water

conservation practices and policies, 83.3% of respondents believed such additional cost

should not be more than 5% over their total monthly water bills.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Yes No Don't Know


174

Figure 6.6 Public opinion on additional water tariff destined towards investments on

water conservation practices and policies

6.2.3 Efficient Water Fittings, Fixtures and Appliances

Residents were asked if their dwelling contained at least one water efficient fitting,

fixture or appliance (Figure 6.7). Overall, few dwellings had water efficient fittings,

fixtures and appliances (19.1%). High income house dwellings had the highest number

of dwellings with water efficient equipment, while mid-high income flats contained the

lowest number of dwellings with water efficient equipment.

Figure 6.7 Water efficient fittings fixtures or appliances within dwellings

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%


Yes No Don't Know

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%


Yes No Don't Know


175

Residents were also asked if they were aware of the existence of water efficient fittings,

fixtures and appliances (Figure 6.8). Although most residents were aware of the

existence of such water efficient equipment, a considerable number demonstrated to be

unaware that such equipment was capable of promoting water savings (39.1%).

Figure 6.8 Public awareness of the existence of water efficient equipment

In order to understand public acceptance over the use of water efficient fittings, fixtures

and appliances residents were asked if they were willing to adapt their dwelling to

install water efficient equipment. Around 80% of them answered yes; only a small

percentage (14.7%) of residents did not agree to use such equipment (Figure 6.9). They

were afraid that might reduce the level of comfort due to their low water flow rate.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%


Aware Unaware


176

Figure 6.9 Public acceptance over the use of water efficient equipment in the dwelling

In short, although the majority of the dwellings did not contain water efficient fittings,

fixtures and appliances (72.4%), most residents were aware that water efficient

equipments are capable of promoting water savings (61%) and would be willing to

install such low-flow devices within their homes (85.3%).

6.2.4 Water Reuse Systems

Public awareness over the existence of water reuse systems and the level of acceptance

towards the reuse of rainwater, greywater and wastewater within dwellings was

measured. Results indicated that residents were aware of water reuse systems, and that

they are capable of promoting water savings inside the home. The great majority of

home owners would be willing to make use of such systems in their dwellings. It was

observed that the reuse of rainwater had a higher rate of acceptance (96.4%) than

greywater (93.3%) and wastewater (78.5%). Detailed results for the different types of

reuse systems are discussed below.

6.2.4.1 Rainwater Harvesting Systems

Overall, almost every resident was aware that treated rainwater can be used for

irrigation, floor washing, vehicle washing, washing clothes and toilet flushing (Figure

6.10), only 6.8% of the interviewed population was unaware of such water reuse

system.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Yes No


177

Figure 6.10 Public awareness of domestic rainwater harvesting systems

The level of acceptance over the non-potable reuse of rainwater at home was high

(Figure 6.11). The majority of residents accepted the use of treated rainwater for non-

potable uses inside and outside their homes (88.1%), however, 8.3% of the interviewed

residents agreed to reuse rainwater only outside their homes to water plants, wash floors

and cars. Some people felt uncomfortable using rainwater for toilet flushing and

washing clothes, afraid that might cause plumbing malfunction and water supply issues

due to plumbing adaptations in their home.

Figure 6.11 Level of acceptance over the reuse of rainwater at home.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Aware Unaware

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Yes Yes, partially No


178

6.2.4.2 Greywater Reuse Systems

Although most residents (87.8%) were aware that treated greywater can be used for

irrigation, external floor washing, vehicle washing, washing clothes and toilet flushing,

12.2% of the interviewed residents were unaware of the existence of greywater reuse

systems (Figure 6.12).

Figure 6.12 Public awareness of domestic greywater recycling systems

Although the level of acceptance for the reuse of greywater in a dwelling was not as

high as rainwater reuse, a considerable amount of residents would agree to use

greywater inside their homes (Figure 6.13). Most residents accepted the limited reuse of

greywater for non-potable purposes inside and outside their homes (84.1%), but 9.2% of

residents felt more comfortable by limiting its reuse for outdoor purposes such as floor

washing and garden irrigation only. Some people felt uncomfortable using greywater

for toilet flushing and washing clothes, afraid that might cause bad odors in the toilets

and clothes. Plumbing adaptation and eventual malfunction was also another concern,

due to sewage and water plumbing refurbishment.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Aware Unaware


179

Figure 6.13 Level of acceptance over the reuse of treated greywater at home

6.2.4.3 Wastewater Reuse Systems

Although the level of awareness over the existence of wastewater reuse systems were

not as high as those from rainwater and greywater, 67.5% of residents were aware that

properly treated and disinfected domestic wastewater can be used for irrigation, vehicle-

washing, external cleansing and flushing toilets (Figure 6.14).

Figure 6.14 Public awareness of domestic wastewater reuse systems

Although the level of acceptance for using properly treated and disinfected domestic

wastewater was not as high as rainwater and greywater reuse, 59.8% of the interviewed

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%



0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%


Aware Unaware


180

residents would agree to reuse wastewater in their homes for both internal and external

non-potable reuses, as long as the water quality of the treated wastewater reached

adequate levels for reuse (Figure 6.15). Not all residents agreed to use treated

wastewater inside their homes, 18.7% would only agree to reuse wastewater on sub-

surface irrigation to avoid any complications related towards water quality.

Figure 6.15 Level of acceptance over the reuse of treated wastewater at home

6.2.5 Dwelling Retrofit and Willingness-to-Pay

Through the use of questionnaires, residents were asked if they would be willing to

retrofit their homes in order to install water-saving features for both environmental and

financial benefits, at what cost, and payback period.

When asked if they would be willing to adapt their dwellings in order to install water-

saving equipments or reuse systems, in average, 74.4% of respondents would invest on

water-saving strategies in their homes, independent of their income range (Figure 6.16).

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%




181

Figure 6.16 Residents willing to adapt their home for water conservation

Those willing to retrofit their dwellings for water conservation, most were willing to

make a monthly investment ranging between R$11.00 and R$50.00 (£3.15 – £14.28).

Figure 6.17 shows that, while high income dwellings were willing to make higher

investments than the other income groups, low income dwellings preferred to limit their

investments only up to R$100.00 per month (£28.57).

Figure 6.17 Level of monthly investment for dwelling retrofit

When residents were asked for how long they would be willing to make such

investments, most responded that they would be willing to pay a fixed rate ranging from

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%


Willing Unwilling

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

Less than R$10

R$11 - R$50 R$51 -R$100

R$101 -R$250

R$251 -R$500

R$501 -R$1000

More than R$1000



182

1 to 6 months (32.4%). In average, high income dwellings demonstrated to be willing to

invest on a fixed rate from 6 to 12 months (30.6%), and most mid-low income dwellings

would be willing to invest for only one month (32.0%), while the majority of mid-high

income dwellings (38.8%), and low income dwellings (45.8%) would rather pay a fixed

amount from 1 to 6 months (Figure 6.18).

Figure 6.18 Duration of monthly investment for dwelling retrofit

When asked for how long would they be willing to wait for the payback of their

investments on water conservation retrofit, and start receiving financial benefits over

water-saving strategies, most residents would expect a short-term payback period from

2 to 6 months only (29.7%). Most low income dwellings (40.5%) and mid-low income

dwellings (44.1%), expected a fast financial return for their investment for 1 month

only, while high income dwellings expected a payback period from 2 to 6 months

(32.9%). Mid-high income flat residents, on the other hand, would be willing to wait for

a financial return ranging from 1 to 2 years (31.8%) (Figure 6.19).

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

1 month only 1 - 6 months 6 - 12 months 1 - 2 years 2 - 3 years More than 3 years



183

Figure 6.19 Expected payback period of investments on dwelling retrofit

6.2.6 Water Conservation Principals

The quantitative questionnaires were also able to measure public concern towards the

future of Federal District’s water resources and importance to conserve water. A small

fraction of the interviewed population (4.6%) demonstrated not to be worried with the

future of water resources, however, 40.2% of the respondents were concerned, and most

were very concerned (55.2%) with the future of local water resources (Figure 6.20).

Figure 6.20 Level of concern over the future of water resources

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

1 month only

2 - 6 months

6 - 12 months

1 - 2 years 2 - 3 years 3 - 5 years 5 - 10 years

More than 10 years


0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%


Not Concerned Concerned Very Concerned


184

Independent of the income range, almost every resident believed to be either important

(21.9%), or very important (77.8%) to conserve water on a daily basis in order to avoid

future water supply issues (Figure 6.21), however, an insignificant number of

respondents felt it was not important to save water on a regular basis (0.4%).

Figure 6.21 Level of importance to conserve water on a daily basis

6.3 Domestic Water Efficiency

The evaluation of water efficient strategies were based on four representative models,

one for each of the different socio-economic residential building typologies in study.

Composed of mean values of dwelling characteristics, baseline water end-use

consumption and public opinion, awareness and acceptance of water efficient strategies

collected from the questionnaire survey and water audits for each income building

typology, these models were used as a basis to evaluate building adaptation, identify

potential water savings and estimate the costs and benefits of water efficient strategies.

6.3.1 Building Adaptation

Overall, the existing water efficient equipments available in the Brazilian market are of

simple installation, rendering little or no refurbishment for their application. The

replacement of existing water faucets and shower heads require no refurbishment and

this can be easily done in a DIY basis. The installation of flow regulators also require no

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%


Not Important Important Very Important


185

refurbishment to the existing plumbing, such fittings can be easily installed without the

need of laboured workforce. Sensor faucets and low-flow toilets on the other hand,

might require laboured workforce and some refurbishment.

Sensor faucets are electrically operated, and consequently, require an electrical

connection or batteries for operation. Although battery operated sensor faucets are

easily adaptable because they require no refurbishment, periodic replacement of battery

is necessary. For residential purposes, electrically operated sensor faucets can be more

user-friendly; nevertheless, they must be connected to an electric outlet, thus, resulting

in the installation of an extra power socket.

Low flush toilet bowls are necessary for the proper functioning of dual flush toilets. As

previously seen, most dwellings presented a 9 litre flush bowl. Such toilet bowls were

designed to use 9 litres of water to activate the siphon effect for solid waste removal,

thus, the installation of dual flush valves in 9 litre toilet bowls would render in their

malfunction. Although the replacement of low flow toilets is relatively simple, this is

usually carried out by skilled labour.

In order to install individual water meters in flat dwellings, a high level of

refurbishment would be necessary. In Brazilian multi-storey buildings, mains water is

commonly supplied indirectly via a header water tank. Vertical individual distributing

pipes are used to feed determined bathrooms, kitchens and utility areas for every floor

level of the multi-storey building. In order to adapt existing buildings for individual

water metering, the existing distribution pipework would have to be disconnected and a

new distribution pipework remodelled in order to fix a water meter per flat dwelling.

Traditionally, Brazilian plumbing installations of every pipework is fitted inside brick

walls, therefore, such building adaptation would render in high costs associated with

labour, materials and redecoration. Such building retrofit was considered onerous, and

extremely inconvenient to residents, therefore it was not considered for analysis.

6.3.2 Domestic Water Reductions

Domestic water reductions for a series of water efficient strategies such as leakage

repair and commercially available water efficient fittings, fixtures and appliances, such

as flow regulators for bathroom, kitchen and utility faucets, automatic bathroom faucet,


186

bathroom sensor faucet, kitchen sensor faucet, low-flow shower head, low-flush toilet,

dual-flush toilet, high-efficiency washing machine, automatic shut-off hose nozzle,

pressure washer and automatic irrigation system, were calculated for the high (Table

6.2), mid-high (Table 6.3), mid-low (Table 6.4) and low (Table 6.5) income dwellings.

As previously seen in Chapter 4, their water savings were determined according to their

potential water reductions (Equation 4.7), using a water reduction index to compare

results (Equation 4.13).

Overall, high-efficiency washing machines proved to be the most effective water

efficient strategy, with an average rate of potable water savings equivalent to 58 m3 per

dwelling per year (m3/dw/yr). In other words, high-efficiency washing machines

promoted a reduction of 21.4% on total domestic water baseline consumption. Results

indicated that the least effective water efficient strategy was the automatic shut-off

nozzle, promoting potable water savings equivalent to an average 3.5 m3 per dwelling

per year, representing only 0.7% reduction over the annual domestic water baseline

consumption.

Figure 6.22 Domestic water reductions per water efficient strategies for high income

dwellings

Figure 6.22 shows that in one hand, the most effective water efficient strategies for high

income houses was the pressure washer with 10.4% water reductions (68 m3/dw/yr),

followed by repair of water leakage, representing a 7.4% reduction over baseline

consumption (39 m3/dw/yr ), and dual flush toilets with 6.9% reductions (17 m3/dw/yr).

10.4

7.4

6.9

4.4

3.9

3.8

3.5

3.2

2.9

2.0

1.7

1.2

1.1

1.0

0 2 4 6 8 10 12

Pressure Washer

Leakage Repair

Dual Flush Toilet

High-Efficiency Washing Machine

Low-Flush Toilet

Kitchen Sensor Faucet

Bathroom Sensor Faucets

Bathroom Faucet Flow Regulator Aerator

Kitchen Faucet Flow Regulator Aerator

Automatic Irrigation Sprinkler System

Low Flow Shower Head

Automatic Shut-off Hose Nozzle

Utility Faucet Flow Regulator

Automatic Bathrom Faucet

Water Reduction Index (%)


187

On the other hand, ineffective water efficient strategies for high income house dwellings

in the Federal District included the automatic bathroom faucet with a low average of

1.0% (5.4 m3/dw/yr), utility faucet flow regulator, representing a 1.1% reduction in

baseline consumption (5.6 m3/dw/yr), and the automatic shut-off hose nozzle, with a

low 1.2% reductions in domestic water consumption (8 m3/dw/yr).

Figure 6.23 Domestic water reductions per water efficient strategies for mid-high

income dwellings

The highest rates of domestic water reductions for mid-high income flat dwellings

included the high-efficiency washing machine, with an estimated 11.7% reduction in

water consumption (29 m3/dw/yr), use of dual flush toilets, with 9.0 % reductions (22

m3/dw/yr), and bathroom faucet flow regulators, with 6.9% reductions (17 m3/dw/yr).

Figure 6.23 shows us that the lowest rates of domestic water reductions for mid-high

income dwellings included the automatic irrigation system, with only 0.1% reduction in

domestic water consumption (0.3 m3/dw/yr), pressure washer, having an estimated 0.7%

reduction in baseline consumption (1.7 m3/dw/yr), and utility faucet flow regulator,

representing a mean 1.8% reduction (4.4 m3/dw/yr). Since most mid-high income

residential building typologies already make use of the automatic shut-off hose nozzles

(see Chapter 5), such strategy was not included in the analysis.

In mid-low income house dwellings, considerable water savings were obtained from the

use of high-efficiency washing machines, with an estimated 36.5% reduction in water

11.7

9.0

6.9

6.6

6.1

5.2

5.0

4.1

1.9

1.8

0.7

0.1

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0


Dual Flush Toilet




Low-Flush Toilet





Pressure Washer




188

consumption (103 m3/dw/yr), followed by dual flush toilets, representing a 9.7%

reduction in baseline water consumption (27 m3/dw/yr) and kitchen sensor faucets, with

7.5% reductions (21 m3/dw/yr). The least effective water efficient strategies for mid-low

income dwellings was water leakage repair, with a low 0.3% reduction in baseline

consumption (0.9 m3/dw/yr) and automatic bathroom faucet, having an estimated 1.3%

reduction in water consumption (3.7 m3/dw/yr) (Figure 6.24).

Figure 6.24 Domestic water reductions per water efficient strategies for mid-low

income dwellings

Figure 6.25 clearly illustrates that effective water efficient strategies for low income

house dwellings included the use of high-efficiency washing machine, with 33.1%

water reductions (77 m3/dw/yr), dual flush toilets, with an estimated 7.8% reduction on

baseline consumption (18 m3/dw/yr), followed by bathroom sensor faucets with 7.1%

reductions (15 m3/dw/yr). The lowest rates of domestic water reductions for low income

house dwellings were the automatic shut-off hose nozzle, representing a low 0.5% in

domestic water reductions (1.2 m3/dw/yr), automatic bathroom faucet, with an average

2.0% water reduction (4.7 m3/dw/yr) and pressure washer, with an estimated 2.2%

reduction in baseline consumption (5.1 m3/dw/yr). Due to the fact that the average

measured flow rates for the existing shower heads and utility faucets in low income

dwellings presented a lower flow rate than that of manufacturer’s reduced flow rate

specifications for low flow shower heads and utility faucet flow regulators, these proved

to be ineffective strategies.

36.5

9.7

7.5

6.3

5.7

4.6

4.3

2.9

2.6

1.3

0.6

0.5

0.3

0 5 10 15 20 25 30 35 40


Dual Flush Toilet



Low-Flush Toilet




Pressure Washer




Leakage Repair



189

Figure 6.25 Domestic water reductions per water efficient strategies for low income

dwellings

It should be noted that there were some limitations when comparing potential water

reductions of faucet flow regulators with automatic and sensor faucets. Firstly, the

methodology developed to identify potential reductions from water efficient flow

regulators was calculated by dividing the average measured fixture flow rate with the

efficient fixture flow rate gathered from manufacturer’s specifications. Secondly,

potential reductions for automatic and sensor faucets were obtained from secondary

sources based in previous studies. In other words, while potential reductions for faucet

flow regulators varied according to baseline flow rates, potential reductions for

automatic and sensor faucets remained stationary.

Although bathroom sensor faucets provided the highest rates in water reduction for

high, mid-low and low income dwellings, results indicated that the use of bathroom

faucet flow regulators in mid-high income dwellings were more effective than sensor

faucets. Estimated potential reductions for bathroom faucet flow regulators were

equivalent to 73%, when compared to the 70% potential reductions from sensor faucets.

In order to explore the upper limit of domestic water reductions that could be obtained

through the use of water efficient strategies for high, mid-high, mid-low and low

income dwellings in the Federal District, the study selected the most effective strategies

33.1

7.8

7.1

7.0

6.7

6.4

5.0

4.1

2.2

2.0

0.5

0 5 10 15 20 25 30 35


Dual Flush Toilet





Low-Flush Toilet

Leakage Repair

Pressure Washer





190

capable of obtaining the highest level of efficiency in domestic water end-use

consumption (Table 6.6).


191

Table 6.2 Potential water reductions per water efficient product for high income dwellings

Water Efficient Strategy Quantity Flow Rate Frequency Potential

Reduction (%)

Baseline

Consumption (m

3/dw/yr)

Reduced

Consumption (m

3/dw/yr)

Water Savings (m

3/dw/yr)

Water

Reduction

Index (%)

Bathroom Faucet Flow Regulator Aerator 6 1.8 l/min 3.8 min/p/d 63 * 27 10 17 3.2 Automatic Bathroom Faucet 6 4.8 l /min 3.1 min/p/d 20 ** 27 22 5 1.0 Bathroom Sensor Faucets (6w) 5 4.8 l/min 1.2 min/p/d 70 * 27 8 19 3.5 Low Flow Shower Head 5 4.5 l/min 6.7 min/p/d 17 * 53 44 9 1.7 Low-Flush Toilet 6 6 l/f 5 f/p/d 33 * 62 41 21 3.9 Dual Flush Toilet 6 3/6 l/f 5 f/p/d 60 * 62 25 37 6.9 Kitchen Sensor Faucet (6w) 2 5.8 l/min 3.5 min/p/d 40 * 51 31 20 3.8 Kitchen Faucet Flow Regulator Aerator 2 1.8 l/min 5.8 min/p/d 30 * 51 36 15 2.9 Utility Faucet Flow Regulator 2 6 l/min 3.2 min/p/d 17 * 34 28 6 1.1 High-Efficiency Washing Machine 1 76 l/load 0.2 load/p/d 46 * 205 27 23 4.4 Automatic Shut-off Hose Nozzle 3 16.8 l/min 15.9 min/dw/d 8 *** 106 80 6 1.2 Pressure Washer (1500w) 1 6 l/min 6.1 min/dw/d 64 * 106 31 55 10.4 Automatic Irrigation Sprinkler System (9V) 1 16.8 l/min 15.1 min/dw/d 12.5 *** 106 75 11 2.0 Leakage Repair --- --- --- 100 39 0 39 7.4

* Based on manufacturer’s specifications ** SABESP (1996) ***Vickers (2001)


192

Table 6.3 Potential water reductions per water efficient product for mid-high income dwellings


Reduction (%)

Baseline

Consumption (m

3/dw/yr)

Reduced

Consumption (m

3/dw/yr)

Water Savings (m

3/dw/yr)

Water

Reduction

Index (%)

Bathroom Faucet Flow Regulator Aerator 3 1.8 l/min 3.1 min/p/d 73 * 23 6 17 6.9 Automatic Bathroom Faucet 3 6.7 l /min 2.5 min/p/d 20 ** 23 18 5 1.9 Bathroom Sensor Faucets (6w) 2 6.7 l/min 0.9 min/p/d 70 * 23 7 16 6.6 Low Flow Shower Head 2 4.5 l/min 5.7 min/p/d 21 * 58 45 12 5.0 Low-Flush Toilet 3 6 l/f 4 f/p/d 33 * 38 25 13 5.2 Dual Flush Toilet 3 3/6 l/f 4 f/p/d 58 * 38 16 22 9.0 Kitchen Sensor Faucet (6w) 2 5.8 l/min 2.7 min/p/d 40 * 38 23 15 6.1 Kitchen Faucet Flow Regulator Aerator 2 1.8 l/min 4.6 min/p/d 27 * 38 28 10 4.1 Utility Faucet Flow Regulator 2 6 l/min 2.7 min/p/d 19 * 24 19 4 1.8 High-Efficiency Washing Machine 1 76 l/load 0.2 load/p/d 54 * 53 25 29 11.7 Pressure Washer (1500w) 1 6 l/min 6.1 min/dw/d 64 * 3 1 1.7 0.7 Automatic Irrigation Sprinkler System (9V) 1 16.8 l/min 15.1 min/dw/d 12.5 *** 3 2.3 0.33 0.1



193

Table 6.4 Potential water reductions per water efficient product for mid-low income dwellings


Reduction (%)

Baseline

Consumption (m

3/dw/yr)

Reduced

Consumption (m

3/dw/yr)

Water Savings (m

3/dw/yr)

Water

Reduction

Index (%)

Bathroom Faucet Flow Regulator Aerator 3 1.8 l/min 2.2 min/p/d 63 * 19 7 12 4.3 Automatic Bathroom Faucet 3 5.1 l /min 1.8 min/p/d 20 ** 19 15 4 1.3 Bathroom Sensor Faucets (6w) 3 5.1 l/min 0.7 min/p/d 70 * 19 6 13 4.6 Low Flow Shower Head 2 4.5 l/min 7.0 min/p/d 17 * 60 52 8 2.9 Low-Flush Toilet 3 6 l/f 3 f/p/d 33 * 49 32 16 5.7 Dual Flush Toilet 3 3/6 l/f 3 f/p/d 60 * 49 21 27 9.7 Kitchen Sensor Faucet (6w) 1 5.4 l/min 3.6 min/p/d 40 * 53 32 21 7.5 Kitchen Faucet Flow Regulator Aerator 1 1.8 l/min 6.0 min/p/d 30 * 53 35 18 6.3 Utility Faucet Flow Regulator 2 6 l/min 2.4 min/p/d 17 * 25 24 2 0.6 High-Efficiency Washing Machine 1 76 l/load 0.2 load/p/d 46 * 201 99 103 36.5 Automatic Shut-off Hose Nozzle 1 9.6 l/min 5.1 min/dw/d 8 *** 19 18 1 0.5 Pressure Washer (1500w) 1 6 l/min 3.4 min/dw/d 64 * 19 12 7 2.6 Leakage Repair --- --- --- 100 1 0 1 0.3



194

Table 6.5 Potential water reductions per water efficient product for low income dwellings


Reduction (%)

Baseline

Consumption (m

3/dw/yr)

Reduced

Consumption (m

3/dw/yr)

Water Savings (m

3/dw/yr)

Water

Reduction

Index (%)

Bathroom Faucet Flow Regulator Aerator 2 1.8 l/min 2.9 min/p/d 63 * 24 9 15 6.4 Automatic Bathroom Faucet 2 4.9 l /min 2.3 min/p/d 20 ** 24 19 5 2.0 Bathroom Sensor Faucets (6w) 2 4.9 l/min 0.9 min/p/d 70 * 24 7 17 7.1 Low Flow Shower Head 2 4.5 l/min 7.8 min/p/d 17 * 51 51 0 0 Low-Flush Toilet 2 6 l/f 2 f/p/d 33 * 34 23 11 5.0 Dual Flush Toilet 2 3/6 l/f 2 f/p/d 60 * 34 16 18 7.8

Kitchen Sensor Faucet (6w) 1 4.7 l/min 3.2 min/p/d 40 * 41 24 16 7.0

Kitchen Faucet Flow Regulator Aerator 1 1.8 l/min 5.3 min/p/d 30 * 41 25 16 6.7 Utility Faucet Flow Regulator 2 6 l/min 2.1 min/p/d 17 * 19 19 0 0 High-Efficiency Washing Machine 1 76 l/load 0.1 load/p/d 46 * 143 66 77 33.1 Automatic Shut-off Hose Nozzle 1 8.9 l/min 4.5 min/dw/d 8 *** 16 15 1 0.5 Pressure Washer (1500w) 1 6 l/min 3.3 min/dw/d 64 * 16 11 5 2.2 Leakage Repair --- --- --- 100 9 0 9 4.1



195

Table 6.6 Baseline water end-uses, and reduced water end-uses through water efficient

strategies applied to the different income dwellings

Baseline Water End-Uses Reduced Water End-Uses

High Income Dwelling

Bathroom Faucet 18 l/p/d Bathroom Sensor Faucets 6 l/p/d Shower Head 36 l/p/d Low Flow Shower Head 30 l/p/d Bidet / Hand Douche 3 l/p/d Bidet / Hand Douche 3 l/p/d Toilet Flush 42 l/p/d Dual Flush Toilet 17 l/p/d Kitchen Faucet 35 l/p/d Kitchen Sensor Faucet 21 l/p/d Water Filter 3 l/p/d Water Filter 3 l/p/d Dishwasher 5 l/p/d Dishwasher 5 l/p/d Utility Faucet 23 l/p/d Utility Faucet with Flow Regulator 19 l/p/d Washing Machine 34 l/p/d High-Efficiency Washing Machine 19 l/p/d Leaks and Losses 27 l/p/d Leakage Repair 0 l/p/d External Tap 2.2 l/m

2/d Pressure Washer and Automatic Irrigation 0.5 l/m

2/d

Swimming Pool Valve 12 l/m2/d Swimming Pool Valve 12 l/m

2/d

Mid-High Income Dwelling

Bathroom Faucet 21 l/p/d Bathroom Faucet with Flow Regulator 6 l/p/d Shower Head 53 l/p/d Low Flow Shower Head 42 l/p/d Bidet / Hand Douche 3 l/p/d Bidet / Hand Douche 3 l/p/d Toilet Flush 35 l/p/d Dual Flush Toilet 15 l/p/d Kitchen Faucet 34 l/p/d Kitchen Sensor Faucet 21 l/p/d Water Filter 3 l/p/d Water Filter 3 l/p/d Dishwasher 1 l/p/d Dishwasher 1 l/p/d Utility Faucet 22 l/p/d Utility Faucet with Flow Regulator 18 l/p/d Washing Machine 49 l/p/d High-Efficiency Washing Machine 22 l/p/d External Tap 0.5 l/m

2/d Pressure Washer and Automatic Irrigation 0.1 l/m

2/d

Mid-Low Income Dwelling

Bathroom Faucet 10 l/p/d Bathroom Sensor Faucets 3 l/p/d Shower Head 33 l/p/d Low Flow Shower Head 26 l/p/d Bidet / Hand Douche 4 l/p/d Bidet / Hand Douche 4 l/p/d Toilet Flush 27 l/p/d Dual Flush Toilet 11 l/p/d Kitchen Faucet 29 l/p/d Kitchen Sensor Faucet 16 l/p/d Water Filter 2 l/p/d Water Filter 2 l/p/d Utility Faucet 14 l/p/d Utility Faucet with Flow Regulator 12 l/p/d Washing Machine 25 l/p/d High-Efficiency Washing Machine 11 l/p/d Leaks and Losses 0.5 l/p/d Leakage Repair 0 l/p/d External Tap 0.7 l/m

2/d Pressure Washer 0.4 l/m

2/d

Low Income Dwelling

Bathroom Faucet 13 l/p/d Bathroom Sensor Faucets 3 l/p/d Shower Head 28 l/p/d Low Flow Shower Head 25 l/p/d Bidet / Hand Douche 1 l/p/d Bidet / Hand Douche 1 l/p/d Toilet Flush 19 l/p/d Dual Flush Toilet 8 l/p/d Kitchen Faucet 22 l/p/d Kitchen Sensor Faucet 12 l/p/d Water Filter 2 l/p/d Water Filter 2 l/p/d Utility Faucet 10 l/p/d Utility Faucet with Flow Regulator 9 l/p/d Washing Machine 17 l/p/d High-Efficiency Washing Machine 7 l/p/d Leaks and Losses 5 l/p/d Leakage Repair 0 l/p/d External Tap 0.7 l/m

2/d Pressure Washer 0.5 l/m

2/d


196

6.3.3 Cost-Benefit Analyses

An economic assessment for the different water efficient strategies was carried out

using: (i) simple payback period; (ii) life cycle cost-benefit analysis and; (iii) average

incremental cost for the high, mid-high, mid-low and low income dwellings (see Tables

6.7, 6.8, 6.9 and 6.10 for a summary of the results).

In order to determine the capital costs of water efficient strategies for each of the

income building typologies, the average number of fixtures and appliances from the

representative model was multiplied by the equipment’s unit cost. This was based on

the assumption that resident’s who are willing to invest in water efficient strategies,

would retrofit the entire dwelling with a set of water-saving equipment. For example, in

order to obtain maximum water efficiency by using low flow toilets in a home, every

toilet in the dwelling would have to be changed.

Although some water efficient strategies included labour costs for their installation,

most were considered easy to install on a DIY basis. In order to work, three out of

thirteen water efficient strategies, required electric installation and consequently, annual

operational costs of energy consumption were estimated according to their individual

consumption frequency. During water auditing, the great majority of the analysed

dwellings presented visible leaks in tap-opening fixtures, therefore, an average capital

costs for leakage repair was estimated according to labour and material costs. The

estimate for the automatic irrigation system on the other hand, was based on the

irrigable garden area from high income dwellings (Appendix I).

Considering the fact that high income residents would be willing to invest an average

maximum of R$600.00 in a year, water efficient strategies such as the bathroom,

kitchen and utility faucet flow regulators, kitchen sensor faucet, low-flush toilets,

automatic shut-off hose, pressure washer and leakage repair, proved to be the options

most likely to be invested for water efficiency in their homes. However, if high income

residents expect a return of their financial investment within 6 months, the bathroom,

kitchen and utility faucet flow regulators, as well as the automatic shut-off hose nozzle,

pressure washer, and leakage repair would be the best alternatives for their investment.

Mid-high income residents, on the other hand, were willing to invest an average

maximum of R$300.00 in a year, therefore, water efficient strategies such as the


197

bathroom, kitchen and utility faucet flow regulator, low-flush toilets, pressure washer

and an automatic irrigation system proved to be the options that would most likely be

invested by residents. However considering the fact that most mid-high income

residents would rather obtain a financial return in 2 years maximum, strategies such as

the low-flush toilet and the automatic irrigation system would not be feasible choices of

investment.

As previously seen, mid-low income resident’s willingness-to-pay for water efficient

strategies was equivalent to an average maximum R$50.00 in a year, and therefore,

would most likely invest in bathroom, kitchen and utility faucet flow regulators,

automatic shut-off hose nozzle and leakage repair. But considering their preference in

obtaining financial return in only one month, only the kitchen faucet flow regulator

would be the best option.

Interestingly, the data collected demonstrated that low income dwellings would be

willing to invest more than mid-low income dwellings, with lower monthly payments

(R$10.00), but within a bigger time-frame (6 months), resulting in an average maximum

of R$50.00 in one year. Considering this, residents would most likely invest in

bathroom and kitchen flow regulators, automatic shut-off hose nozzle and repair

existing leaks, but if considering their desired payback period of only one month, no

strategies would be viable.

6.3.3.1 Simple payback period

The simple payback period shows how long it takes for financial savings to cover the

cost of an efficient water conservation measure. The economic assessment using

payback period has shown that automatic bathroom faucet, bathroom faucet, low flow

shower heads, high efficiency washing machine, and automatic irrigation sprinkler

present the highest payback period of around 20 years, turning them unfeasible.

Moreover, the payback period is higher than their average life expectancy. The other

efficient strategies are feasible taking into account the payback period analysis. Tables

6.7 to 6.10.

Using the simple payback period analysis we could say that 9 out of the 15 strategies

analysed are feasible. However, the payback period does not take into account the

savings generated over the lifetime of the equipment and it does not provide a simple


198

criteria for acceptance or rejection of one strategy. So, we proceed to calculate the life

cycle cost-benefit analysis.

6.3.3.2 Life cycle analysis

A life cycle cost-benefit analysis (LCCB) was capable of evaluating the financial

benefits generated by every water efficient strategy within their lifespan. Figure 6.26

shows that the repair of leaks in high income dwellings presented the highest financial

benefit equivalent to R$6,063.27, followed by dual flush toilets (R$3,153.29) and low-

flush toilets (R$2,236.41). On the other hand, automatic shut-off hose nozzle and faucet

flow regulator presented a very low benefit.

Figure 6.26 Life cycle cost benefit analysis of feasible water efficient strategies for high

income dwellings

For mid-high income dwellings, the bathroom faucet flow regulator proved to provide

the highest financial benefits during its lifespan (R$1,050.53), followed by the dual

(R$766.36) and low-flush (R$689.37) toilets and by kitchen faucet flow regulator

aerator (R$633.71) (Figure 6.27).

R$ 6.063.27

R$ 3.153.29

R$ 2.236.41

R$ 1.850.20

R$ 1.822.48

R$ 1.802.80

R$ 1.630.15

R$ 648.65

R$ 180.06

R$0 R$1,000 R$2,000 R$3,000 R$4,000 R$5,000 R$6,000 R$7,000

Leakage Repair

Dual Flush Toilet (3/6 lpf)

Low-Flush Toilet (6 lpf)

Bathroom Faucet Flow Regulator

Kitchen Sensor Faucet (6w)

Kitchen Faucet Flow Regulator

Pressure Washer




199


high income dwellings

Figure 6.28 shows us that the use of high-efficiency washing machines provided the

highest financial benefit (R$2,005.22) for mid-low income dwellings, followed by the

dual flush toilet (R$1,328.10) and the kitchen faucet flow regulator (R$1,243.56).

Kitchen sensor faucet and low-flush toilet also presented a high financial benefit.


low income dwellings

R$ 1.050.53

R$ 766.36

R$ 689.37

R$ 633.71

R$ 377.96

R$ 271.76

R$ 34.38

R$ 4.03

R$0 R$200 R$400 R$600 R$800 R$1,000 R$1,200







Pressure Washer


R$ 2.005.22

R$ 1.328.10

R$ 1.243.56

R$ 1.197.45

R$ 1.044.07

R$ 811.32

R$ 94.65

R$ 13.04

R$0 R$500 R$1,000 R$1,500 R$2,000 R$2,500










200

For low income dwellings, the kitchen faucet flow regulator (R$856.96) presented the

highest financial benefits during its lifespan, followed by the bathroom faucet flow

regulator (R$797.83) and leakage repair (R$654.74). Kitchen sensor faucet, dual flush

toilet and low flush toilet also presented a reasonable benefit (Figure 6.29).

Figure 6.29 Life cycle cost benefit analysis of feasible water efficient strategies for low

income dwellings

Using the life cycle cost-benefit analysis we could say that, except for automatic shut-

off hose nozzle, utility faucet flow regulators, pressure washer, the strategies analysed

provide reasonable financial benefit.

6.3.3.3 Average incremental cost-benefit analysis - AIC

In order to appraise different types of water efficient strategies with different life

expectancies, the average incremental cost-benefit analysis (AIC) was used in order to

compare the cost effectiveness of the feasible water efficient strategies using a time

horizon of 30 years. Overall, all the strategies analysed present the highest financial

return per cubic meter of water saved, for high income (between R$ 5.13 and R$ 3.24

per cubic meter) dwellings and the low financial return for the low income dwellings

(between R$0.04 and R$ 2.30 per cubic meter). Figures 6.30 to 6.33 rank the average

incremental cost of feasible water efficient strategies for the different income dwellings.

R$ 856.96

R$ 797.83

R$ 654.74

R$ 599.47

R$ 557.01

R$ 553.99

R$ 262.30

R$ 1.49

R$0 R$100 R$200 R$300 R$400 R$500 R$600 R$700 R$800 R$900



Leakage Repair







201

Estimates for high income dwellings shows that the kitchen faucet flow regulator

provided the highest rate of financial return of R$5.13 per cubic meter of water saved,

followed by the repair of leaks (5.13 R$/m3), and utility faucet flow regulator (4.99

R$/m3). The highest ranked water efficient strategy for mid-high income dwellings was

the pressure washer, with R$2.87 per m3 of water saved, followed by the kitchen faucet

flow regulator (2.75 R$/m3) and bathroom faucet flow regulator (R$/m3). For mid-low

income dwellings, the best alternatives for investment was the kitchen faucet flow

regulator (2.35 R$/m3), the bathroom faucet flow regulator (2.24 R$/m3) and the low-

flush toilet (2.15 R$/m3). The highest rates for financial return in low income dwellings

was the repair of leaks, at 2.30 R$/m3, followed by the kitchen faucet flow regulator

(1.83 R$/m3), and the use of bathroom faucet flow regulators (1.78 R$/m3).


strategies for high income dwellings

5.13

5.13

4.99

4.74

4.47

3.86

3.71

3.42

3.24

0.00 1.00 2.00 3.00 4.00 5.00 6.00


Leakage Repair




Pressure Washer




30 year AIC (R$/m3)


202


strategies for mid-high income dwellings


strategies for mid-low income dwellings

R$ 2.87

R$ 2.75

R$ 2.69

R$ 2.60

R$ 1.68

R$ 0.57

R$ 0.37

R$ 0.20

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Pressure Washer








30 year AIC (R$/m3)

2.35

2.24

2.15

1.99

1.89

1.61

1.30

0.65

0.30

0.00 0.50 1.00 1.50 2.00 2.50







Leakage Repair



30 year AIC (R$/m3)


203


strategies for low income dwellings

2.30

1.83

1.78

1.61

1.23

1.03

0.11

0.04

0.00 0.50 1.00 1.50 2.00 2.50

Leakage Repair








30 year AIC (R$/m3)


204

Table 6.7 Cost-benefit analyses of water efficient strategies for high income dwellings

Water Efficient Strategies Water Savings

(m3/dw/yr)

Financial

Benefits (R$/dw/yr)

Capital Cost (R$/dw)

Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Bathroom Faucet Flow Regulator 17 134.14 93.00 0.00 0.7 20 1,850.20 4.74

Automatic Bathroom Faucet 5 42.93 900.00 0.00 21.0 20 -261.37 -5.94

Bathroom Sensor Faucets 19 150.24 2,900.00 0.50 19.4 20 -738.86 -5.19

Low Flow Shower Head 9 70.32 849.50 0.00 12.1 5 -2,214.25 -14.06

Low-Flush Toilet (6 lpf) 21 163.71 455,58 0.00 2.8 23 2,236.41 4.47

Dual Flush Toilet (3/6 lpf) 37 292.48 1,656.18 0.00 5.7 23 3,153.29 3.71

Kitchen Sensor Faucet 20 163.21 600.00 0.38 3.7 20 1,822.48 3.24

Kitchen Faucet Flow Regulator 15 122.41 18.34 0.00 0.1 20 1,802.80 5.13

Utility Faucet Flow Regulator 6 44.83 18.34 0.00 0.4 20 648.65 4.99

High-Efficiency Washing Machine 23 184.89 2,184.00 0.00 11.8 10 -606.82 -4.21

Automatic Shut-off Hose Nozzle 6 51.53 55.95 0.00 1.1 5 180.06 3.42

Pressure Washer 55 441.72 329.90 13.73 0.8 5 1,630.15 3.86

Automatic Irrigation Sprinkler System 11 85.89 1,445.81 9.90 19.0 7.5 -912.38 -13.06

Leakage Repair 39 314.45 100.00 0.00 0.3 30 6,063.27 5.13


205

Table 6.8 Cost-benefit analyses of water efficient strategies for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Bathroom Faucet Flow Regulator 17 73.74 46.50 0.00 0.6 20 1,050.53 2.69

Automatic Bathroom Faucet 4.6 20.14 450.00 0.00 22.3 20 -150.32 -3.68

Bathroom Sensor Faucets 16 70.50 1,160.00 0.10 16.5 20 -112.58 -1.96

Low Flow Shower Head 12 54.04 339.80 0.00 6.3 5 -92.30 -2.66

Low-Flush Toilet (6 lpf) 13 55.78 227.79 0.00 4.1 23 689.37 1.68

Dual Flush Toilet (3/6 lpf) 22 96.96 828.09 0.00 8.5 23 766.36 0.37

Kitchen Sensor Faucet 15 66.03 600.00 0.30 9.1 20 377.96 0.20

Kitchen Faucet Flow Regulator 10 43.83 18.34 0.00 0.4 20 633.71 2.75

Utility Faucet Flow Regulator 4.4 19.50 18.34 0.00 0.9 20 271.76 2.60

High-Efficiency Washing Machine 29 126.00 2,184.00 0.00 17.3 10 -1,109.17 -7.29

Pressure Washer 1.7 7.51 0.01 0.00 0.0 5 34.38 2.87

Automatic Irrigation Sprinkler System 0.3 1.46 4.58 0.23 3.7 5 4.03 0.57


206

Table 6.9 Cost-benefit analyses of water efficient strategies for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Bathroom Faucet Flow Regulator 12.1 57.66 46.50 0.00 0.8 20 811.32 2.24


Bathroom Sensor Faucets 13.0 62.38 1,740.00 0.33 28.0 20 -816.89 -2.09

Low Flow Shower Head 8.1 38.62 339.80 0.00 8.8 5 -162.92 -0.67

Low-Flush Toilet (6 lpf) 16.2 77.35 227.79 0.00 2.9 23 1,044.07 2.15

Dual Flush Toilet (3/6 lpf) 27.4 131.13 828.09 0.00 6.3 23 1,328.10 1.61

Kitchen Sensor Faucet 21.1 101.04 300.00 0.39 3.0 20 1,197.45 1.89

Kitchen Faucet Flow Regulator 17.6 84.20 9.17 0.00 0.1 20 1,243.56 2.35

Utility Faucet Flow Regulator 1.6 7.59 18.34 0.00 2.4 20 94.65 1.99

High-Efficiency Washing Machine 102.7 491.10 2,184.00 0.00 4.4 10 2,005.22 0.65

Automatic Shut-off Hose Nozzle 1.4 6.92 18.65 0.00 2.7 5 13.04 0.30

Pressure Washer 7.2 34.60 329.90 9.42 13.1 5 -214.60 -0.99

Leakage Repair 0.9 4.36 50.00 0.00 11.5 30 35.54 1.30


207

Table 6.10 Cost-benefit analyses of water efficient strategies for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Bathroom Faucet Flow Regulator 14.9 55.71 31.00 0.00 0.6 20 797.83 1.78


Bathroom Sensor Faucets 16.5 61.64 1,160.00 0.43 19.0 20 -249.38 -0.50

Low-Flush Toilet (6 lpf) 11.5 42.93 151.86 0.00 3.5 23 553.99 1.61

Dual Flush Toilet (3/6 lpf) 18.1 67.45 552.06 0.00 8.2 23 557.01 1.03

Kitchen Sensor Faucet 16.3 60.81 300.00 0.35 5.0 20 599.47 1.23

Kitchen Faucet Flow Regulator 15.6 58.22 9.17 0.00 0.2 20 856.96 1.83

High-Efficiency Washing Machine 76.8 286.78 2,184.00 0.00 7.6 10 262.30 0.11

Automatic Shut-off Hose Nozzle 1.2 4.40 18.65 0.00 4.2 5 1.49 0.04

Pressure Washer 5.1 19.10 329.90 8.92 32.4 5 -283.26 -1.85

Leakage Repair 9.5 35.45 40.00 0.00 1.1 30 654.74 2.30


208

6.4 Rainwater Harvesting Systems

Typological characteristics such as roof area, garden/yard area, plot size, built form and

typical plumbing installations were included to the four representative models created to

represent high, mid-high, mid-low and low income dwellings from the Federal District,

to evaluate the viability of rainwater harvesting systems in terms of their applicability

(through building adaptation and public acceptance), domestic water savings, system

costs, and benefits. Residential flat buildings were considered as an entire typological

unit. Although system composition, dimensioning and building adaptation of rainwater

harvesting systems were evaluated as a whole, domestic water reductions, and cost-

benefits were divided between the average numbers of flat dwellings in the building.

The average monthly rainwater supply was estimated according to mean values of roof

area collected during fieldwork (See Chapter 5, Table 5.3) and secondary historical data

for mean monthly precipitation from the Federal District (METEOTEST, 1999). Due to

the fact that most rooftops were composed of pitched ceramic tiles or fibre-cement

roofing sheets, a coefficient of 0.9 was used to consider rainwater losses during runoff

(Leggett et al., 2001a). Commercially available filters with 90% efficiency were also

considered as a basis for estimating collectable rainwater (WISY, 2010).

As previously seen in Chapter 4, three different types of rainwater demands were

derived for analysis:




To evaluate rainwater harvesting systems, two scenarios were considered. The first

scenario consisted in analysing the performance of rainwater harvesting systems based

on baseline water end-use consumption. The second scenario analysed the performance

of rainwater harvesting systems in combination with water efficient strategies. Monthly

rainwater demands for the different types of reuse were estimated according to Table

6.6. Irrigation and floor washing rainwater demands were estimated together due to the

fact that both activities would make use of the same water fixture.


209

Due to the fact that the capacity of rainwater storage has a direct influence over the

costs of a rainwater harvesting system and the volume of mains water savings (Fewkes

and Butler, 2000), the performance of a series of rainwater storage volumes was

evaluated for the different rainwater demands described above using Equation 4.11.


The applicability of rainwater harvesting systems in terms of building adaptation was

evaluated according to the typological characteristics of built form, built area, plot size

and typical plumbing installations for the different income dwellings. Based on such

parameters, hypothetical configurations of rainwater harvesting systems were composed

for the high, mid-high, mid-low and low income dwelling representative models.

In one hand, the great majority of house dwellings from the studied regions did not

contain rainwater collection pipework or drainage system, hence, the installation of

gutters, downpipes, collection and drainage network would be necessary. The

composition of each rainwater collection pipework was determined according to the

minimum collection area necessary to supply demand, hence reducing unnecessary

installation costs and optimizing the rainwater harvesting systems. So as to simplify

installation, rainwater storage tanks were perceived to be located in the front yard of the

house, next to the urban drainage collection network, reducing installation costs for

rainwater drainage pipework.

On the other hand, due to their building scale, all residential flat buildings presented

both rainwater collection and drainage pipework, resulting in minor changes to the

existing system. In this case, the rainwater collection pipework was perceived to collect

the necessary rainwater to supply demand. Hypothetically, this would be done on

ground level, either by diverting a section of the existing collection pipes, or through the

use of a diversion chamber, to separate the necessary volume of rainwater to an

underground storage tank located in the proximity of the building. Surplus rainwater

from storage overflow or self-cleaning filter would be easily adapted to the existing

rainwater drainage network.

Since mains water distribution to outdoor end-uses in Brazil is commonly directly fed

from the incoming service pipe, treated rainwater distribution to outdoor end-uses such

as irrigation and floor washing proved to be a simple, low budget scheme that could be


210

either adapted to the existing pipework or be installed separately, avoiding cross-

connections between potable and non-potable water.

On the other hand, indoor water end-uses in Brazilian dwellings are indirectly fed via a

header water tank located at the building’s loft. Water from the header tank is usually

distributed through a branching network of header pipes located at the loft of the

building, which individually feed bathrooms, kitchen, utility and other water-consuming

spaces of a house or flats via a vertical distributing pipe. Usually, a single distribution

branch feeds more than one fixture or appliance within these ‘wet spaces’, however, it

was common to find dwellings containing high-pressure flush valves instead of tank-fill

flush valves. Typically, high-pressure flush valves contain a separate distribution

pipework designated solely for toilet flushing, while tank-fill flush valves are part of a

single distribution branch.

The installation of a new distribution pipework destined for non-potable end-uses would

require a high level of refurbishment to adapt the existing network and install a new

distribution branch separated from mains water. Due to the fact that pipes are commonly

located inside brick walls, it would be necessary to break part of the wall to have access

to the existing plumbing and to install the new pipework. Hence, this operation would

render in the redecoration of bathrooms and utility areas. Such retro-fitting option was

considered inefficient, onerous and extremely inconvenient to residents.

A simple and effective way of adapting existing dwellings for non-potable indoor water

reuse was derived by simply modifying the existing header pipework layout at loft

level. The existing vertical distributing pipes which only feed non-potable end-uses

could be used to supply treated rainwater to high pressure flush valves, utility faucets

and washing machines. Such retrofitting technique was considered a low cost method

for adapting existing buildings for water reuse because it requires little plumbing work

and excludes the need to redecorate ‘wet spaces’, as well as promoting little

inconvenience to residents.

The above technique of building adaptation via header pipework modification, however,

would only be made possible in situations where a single vertical distributing pipe was

solely designated to feed non-potable distribution branches. Buildings which contain a

single distribution branch feeding both potable and non-potable end-uses, requires the


211

installation of a separate distribution pipework for non-potable purposes. Considering

the fact that the installation of a new distribution pipework destined for non-potable

end-uses would be of high-cost and inconvenient to residents, such option was ruled out

of analysis and the study focused on a more realistic solution, through the adaptation of

existing buildings via header pipework modification at loft level.


Domestic water reductions of different rainwater storage volumes for the four different

types of rainwater demands were estimated for the different dwelling income typologies

according to two scenarios: (i) Baseline water end-use consumption and (ii) Reduced

water end-use consumption. The first, considered current domestic water end-use

consumption, and the latter, considered the possibility of achieving high water

efficiency through the use of effective water efficient strategies in combination with

rainwater harvesting systems, resulting in a reduced rainwater demand and smaller

rainwater storage volumes.

Dealing with large storage volumes, this investigation concentrated on the use of

historical mean monthly precipitation values with mean monthly rainwater demand

figures of baseline and reduced end-uses to simulate the performance of different

rainwater storage volumes and obtain annual data of potable water savings for high

(Appendix J), mid-high (Appendix K), mid-low (Appendix L) and low (Appendix M)

income dwellings. As previously seen in Chapter 4, water savings for the different

storage volumes of commercially available rainwater cisterns were identified through

behavioural analysis simulation based on monthly time intervals using Equation 4.11.

Overall, results indicated that higher water savings were obtained for baseline water

end-use consumption than for reduced water end-use consumption when using the same

rainwater storage volume (Figures 6.34, 6.35, 6.36 and 6.37). It was observed that, at

first, annual water savings rose proportionally to the increase in rainwater storage

volume, however, water savings stagnated once the rainwater harvesting system

achieved its maximum capacity to promote domestic water reductions, independent of

the increase in storage volume.

The ideal storage capacity was defined as the lowest rainwater storage volume capable

of promoting the highest level of water savings. Hence, peak water savings were


212

achieved as soon as the rainwater harvesting system reached their ideal storage capacity,

and after this point, water savings stagnated, rendering larger rainwater storage volumes

unviable options.

On the whole, results indicated that houses contained the necessary roof area for

collecting rainwater throughout the year to supply demand. In particular, residential flat

buildings contained insufficient average roof area to collect enough rainwater

throughout the year to adequately supply most rainwater reuse demands. Results

indicated that residential flat buildings were capable of collecting enough rainwater

throughout the year to supply reduced rainwater end-use demands for garden irrigation,

floor washing and toilet flushing (Reuse 2), however, this would lead to spacious

rainwater storage volumes, which could lead to issues related to lack of area available

for the construction of the rainwater cisterns. Although the ideal storage capacity for

such reduced rainwater end-use demands would be equivalent to 420 m3, this

investigation analysed the possibility of installing smaller rainwater storage volumes,

and estimated their water savings. Rainwater harvesting systems destined to supply

communal outdoor end-uses (Reuse 1) proved to require much smaller rainwater storage

volumes, with an ideal storage capacity of 35 m3 for baseline water end-use

consumption and 15 m3 for reduced water end-use consumption.

Figure 6.34 Annual water savings per rainwater storage volumes for high income

dwellings

0

50

100

150

200

250

1 10 20 30 40 50 60 70 80 90 100 110 120

An

nu

al W

ate

r S

av

ing

s(m

3 /yr

)

Rainwater Storage Volume (m3)

Baseline Reuse 1 Reduced Reuse 1 Baseline Reuse 2

Reduced Reuse 2 Baseline Reuse 3 Reduced Reuse 3


213

Figure 6.35 Annual water savings per rainwater storage volumes for mid-high income

dwellings

Figure 6.36 Annual water savings per rainwater storage volumes for mid-low income

dwellings

0

100

200

300

400

500

600

700

800

900

1000

1 10 20 30 40 50 60 70 80 90 100 110 120

An

nu

al W

ate

r S

av

ing

s (m

3 /yr

)


Baseline Reuse 1 Reduced Reuse 1 Reduced Reuse 2

0

20

40

60

80

100

120

140

1 5 10 15 20 25 30 35 40 45 50 60 70 80 90 100 110 120

An

nu

al W

ate

r S

av

ing

s(m

3 /yr

)





214

Figure 6.37 Annual water savings per rainwater storage volumes for low income

dwellings


high income dwellings in baseline and reduced water end-use consumption scenarios

Rainwater Harvesting

System Storage Volume

Baseline Scenario Reduced Scenario

Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

Re

use

1 1m

3 Rainwater Cistern 59 11.0 15 65.9

5m3 Rainwater Cistern 63 11.8 19 66.7


15m3 Rainwater Cistern 73 13.7 --- ---

Re

use

2









Re

use

3









0

20

40

60

80

100

120

1 5 10 15 20 25 30 35 40 45 50 60 70 80 90 100 110 120

An

nu

al W

ate

r S

av

ing

s(m

3 /yr

)





215


mid-high income dwellings in baseline and reduced water end-use consumption

scenarios




Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

Re

use

1

1m3 Rainwater Cistern 1.7 0.7 0.4 42.7



15m3 Rainwater Cistern 2.1 0.9 --- ---



Re

use

2

50m3 Rainwater Cistern --- --- 11 53.6










mid-low income dwellings in baseline and reduced water end-use consumption

scenarios




Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

Re

use

1 1m





Re

use

2 5m





Re

use

3











216


low income dwellings in baseline and reduced water end-use consumption scenarios




Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

Re

use

1

1m3 Rainwater Tank 11 4.9 8 39.9



Re

use

2

1m3 Rainwater Tank 34 14.5 19 44.5



15m3 Rainwater Cistern 48 20,6 --- ---


Re

use

3







Tables 6.11, 6.12, 6.13 and 6.14, summarize the results of annual water savings per

dwelling of the varied rainwater harvesting systems for the different income dwellings,

and their water reduction index (WRI) achieved according to baseline and reduced end-

use consumption scenarios. Although the rainwater harvesting systems presented higher

annual water saving figures for the baseline water end-use consumption scenario for the

reduced water end-use consumption scenario, the water reduction indexes proved that

the use of water efficient strategies in combination with rainwater harvesting systems

resulted in potentially high domestic water reductions.

Domestic water savings for high income house dwellings ranged from 15 m3 per

dwelling per year (m3/dw/yr) to 229m3/dw/yr, depending on the rainwater harvesting

system storage volume and end-use water consumption scenario. Potentially, domestic

water reductions could reach to 100%, through the combination of water efficient

strategies and a rainwater harvesting system with a 70 m3 rainwater storage volume for

the reduced potable end-use water consumption of 223m3/dw/yr, hypothetically

achieving mains water independence.

The highest rate of domestic water savings for mid-high income flat dwellings was

equivalent to 16m3/dw/yr through a 450 m3 rainwater harvesting system for reduced

communal outdoor end-uses and toilet flushing (Reuse 2), with a water reduction index

equivalent to 59 %. Communal outdoor water end-uses required lower rainwater storage


217

volumes ranging from 1m3 to 25m3 with domestic water savings per dwelling ranging

from a low 0.4 m3/dw/yr at a reduced water consumption scenario to 1.0 m3/dw/yr at a

baseline water consumption scenario, with WRI’s ranging from 0.7% (baseline

scenario) to 42.8% (reduced scenario).

Domestic water savings from baseline water end-use consumption scenario for mid-low

income house dwellings ranged from 14m3/dw/yr to 122m3/dw/yr, while the reduced

scenario presented figures ranging from 9m3/dw/yr to 78m3/dw/yr. Since the reduced

water end-use scenario for mid-low dwellings allowed the application of a rainwater

harvesting system for potable end-uses, higher annual water savings could be achieved,

reaching up to 64.9% water reduction index.

Low income house dwellings presented domestic water reduction figures ranging from

11m3/dw/yr to 96m3/dw/yr for the baseline water consumption scenario and 8m3/dw/yr

to 59m3/dw/yr for a reduced water consumption scenario. Similarly to mid-low income

house dwellings, the reduced domestic water consumption rates for low-income house

dwellings allowed the application of a rainwater harvesting system for potable end-uses,

leading to higher annual water savings, with water reduction indexes reaching up to a

62.1%.


In order to assess the economic benefits of rainwater harvesting systems for high, mid

high, mid-low and low income dwellings, simple payback period, life cycle cost-benefit

analysis and average incremental cost evaluation methods were applied to both baseline

and reduced water end-use consumption scenario’s (see Tables 6.15 to 6.22 for the

results).

Costs for rainwater harvesting systems included the unit costs of system components for

collection, drainage and distribution pipework, water tanks, treatment system and other

related equipments. Installation costs for water reuse systems were composed of site

preparation and labour. Operational costs included annual consumables, energy

consumption and labour cost for system maintenance (Appendix N).


218

Using the simple payback period analysis, in both baseline and reduced water end-use

consumption scenario’s, no rainwater harvesting system was considered as a viable

option for high, mid-low and low income dwellings because, excepting for the baseline

scenario for high income dwellings, the payback period proved to be higher than the life

expectancy of the equipment.

Moreover, these systems required an investment superior to the resident’s willingness-

to-pay. Most rainwater harvesting systems for mid-high income dwellings did not

achieve the minimum level of resident willingness-to-pay of R$300.00 in one year. But

due to the fact that mid-high income flat dwellings would have to share the costs related

to one rainwater harvesting system for outdoor end-uses within communal grounds of

their building typology, results indicated that residents would be willing to invest in a

rainwater harvesting system for baseline water consumption on garden irrigation and

floor washing with a storage capacity ranging from 1m3 to 25m3. However, if they

expect to receive a financial return of investment within two years, these would prove to

be unviable options.

The financial benefits obtained from rainwater harvesting systems during their useful

life expectancy was analysed for the different income dwellings, and overall, such water

conservation measure proved to be an unviable option for the reduced water end-use

consumption scenario due to the high capital costs related to the investment of water

efficient equipment, in addition to the rainwater harvesting system implementation

costs.

No rainwater harvesting system was found to be feasible for mid-low and low income

dwellings due to the high capital costs involved and the low water consumption rate

from these homes. However, due to the fact that high income dwellings presented an

average high water consumption rate, some rainwater harvesting systems for baseline

water end-use consumption scenario demonstrated to be viable options for investment.

With the highest financial benefit rainwater harvesting systems for irrigation, floor

washing, toilet flushing and clothes washing (Reuse 3), provided a financial return of

R$12,174.37 using a 10m3 rainwater cistern, R$7,992.06 with a 20m3 rainwater cistern

and R$6,213.55 from a 30m3 rainwater cistern (Figure 6.38).


219




mid-high income dwellings

Due to the fact that multi-storey residential buildings were densely populated, with a

relatively small shared roof area for rainwater collection, rainwater reuse for non-

potable indoor end-uses for both baseline and reduced water consumption scenarios

proved to be an unviable option for investment. However, rainwater harvesting systems

for outdoor baseline water consumption end-uses on irrigation and floor washing (Reuse

R$ 12,174.37

R$ 7,992.06

R$ 6,213.55

R$ 5,134.42

R$ 3,025.23

R$ 1,716.01

R$ 1,546.09

R$ 1,042.07

R$ 497.33

R$0 R$4,000 R$8,000 R$12,000 R$16,000

10m3 Rainwater Cistern - Reuse 3






5m3 Rainwater Cistern - Reuse1



R$ 57.87

R$ 31.33

R$ 27.22

R$ 6.29

R$0 R$10 R$20 R$30 R$40 R$50 R$60 R$70






220

1), proved to be feasible options for investment, due to the shared capital costs of

investment and relatively small communal garden/yard area per flats. Figure 6.39 shows

that the most feasible rainwater storage size for a rainwater harvesting system for

irrigation and floor washing was 1m3, with a financial return of R$57.87, followed by a

10m3 cistern (R$31.33) and a 5m3 cistern (R$27.22).

Figure 6.40 Average incremental cost of feasible rainwater harvesting systems for high

income dwellings

An average incremental cost-benefit analysis was used in order to compare the cost

effectiveness of the feasible rainwater harvesting systems within a time horizon of 30

years in terms of financial return per cubic meter of water saved (R$m3), for the high

(Figures 6.40) and mid-high (Figure 6.41) income dwellings. Overall, the highest rate of

financial return was obtained from the 1m3 rainwater cistern for irrigation and floor

washing in high income dwellings, followed by the 10m3 (2.49 R$/m3), and 30m3 (1.13

R$/m3) rainwater cisterns for baseline water end-use consumption in irrigation, floor

washing, toilet flushing and clothes washing. For mid-high income dwellings, the

highest rate of financial return was obtained by using a 1m3 rainwater cistern (1.11

R$/m3) followed by a 10m3 rainwater cistern (0.52 R$/m3) and a 5m3 rainwater cistern

(0.48 R$/m3), for baseline outdoor water end-use in irrigation and floor washing.

R$ 2.91

R$ 2.49

R$ 1.54

R$ 1.13

R$ 0.84

R$ 0.82

R$ 0.52

R$ 0.32

R$ 0.16

R$ 0.00 R$ 0.50 R$ 1.00 R$ 1.50 R$ 2.00 R$ 2.50 R$ 3.00 R$ 3.50





10m3 Rainwater Cistern- Reuse 1






221

Figure 6.41 Average incremental cost of feasible rainwater harvesting systems for mid-


R$ 1.11

R$ 0.52

R$ 0.48

R$ 0.10

R$ 0.00 R$ 0.20 R$ 0.40 R$ 0.60 R$ 0.80 R$ 1.00 R$ 1.20






222

Table 6.15 Cost-benefit analyses of rainwater harvesting systems on a baseline water end-use scenario for high income dwellings

Rainwater Harvesting System Water Savings

(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1 1m

3 Rainwater Cistern 59 468.57 1,846.85 14.18 4.1 30 5,134.42 2.91

5m3 Rainwater Cistern 63 500.48 5,521.65 14.18 11.4 30 1,546.09 0.82


15m3 Rainwater Cistern 73 580.25 8,752.65 14.18 15.5 30 -211.57 -0.10

Re

use

2

5m3 Rainwater Cistern 103 603.44 8,516.78 22.55 14.7 30 497.33 0.16


15m3 Rainwater Cistern 113 683.20 11,747.78 22.55 17.8 30 -841.18 -0.25

20m3 Rainwater Cistern 118 723.09 14,828.58 22.55 21.2 30 -3,140.24 -0.89





Re

use

3

10m3 Rainwater Cistern 163 1,298.41 10,144.00 38.75 8.1 30 12,174.37 2.49




50m3 Rainwater Cistern 203 1,617.48 33,091.00 38.75 21.0 30 -4,518.68 -0.74





223

Table 6.16 Cost-benefit analyses of rainwater harvesting systems on a reduced water end-use scenario for high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1




Re

use

2




Re

use

3









224

Table 6.17 Cost-benefit analyses of rainwater harvesting systems on a baseline water end-use scenario for mid-high income dwellings

Rainwater Harvesting System Water

Savings (m

3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1

1m3 Rainwater Cistern 1.7 7.62 40.23 0.36 5.5 30 57.87 1.11




20m3 Rainwater Cistern 2.3 10.06 170.52 0.36 17.6 30 -24.52 -0.36

25m3 Rainwater Cistern 2.4 10.67 193.73 0.36 18.8 30 -35.76 -0.49

Table 6.18 Cost-benefit analyses of rainwater harvesting systems on a reduced water end-use scenario for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1

1m3 Rainwater Cistern 0.4 1.85 4,082.37 0.36 2729.5 30 -4,097.33 -324.39



Re

use

2







225

Table 6.19 Cost-benefit analyses of rainwater harvesting systems on a baseline water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1 1m

3 Rainwater Cistern 13.6 65.26 1,664.40 4.68 27.5 30 -2,072.92 -5.06




Re

use

2 5m





Re

use

3











226

Table 6.20 Cost-benefit analyses of rainwater harvesting systems on a reduced water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1



Re

use

2 5m




Re

use

3








227

Table 6.21 Cost-benefit analyses of rainwater harvesting systems on a baseline water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1




Re

use

2 5m





Re

use

3








228

Table 6.22 Cost-benefit analyses of rainwater harvesting systems on a reduced water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Re

use

1



Re

use

2



Re

use

3






229

6.5 Greywater Recycling Systems

The representative models composed to represent each income dwelling typology were

used as a basis to evaluate the viability of greywater reuse systems in terms of their

applicability through building adaptation, domestic water reductions and cost-benefits.

Similar to rainwater harvesting systems, greywater recycling systems for residential flat

buildings were considered as one typological unit composed of 72 flat dwellings.

Although greywater recycling system composition, dimensioning and building

adaptability were evaluated at the residential building scale, water savings, costs and

benefits were shared amongst flat dwellings as means for comparison between

residential dwelling types.

Four different types of greywater systems were analysed. The first consisted in simply

storing greywater from the washing machine in a 300 litre greywater butt for irrigation

and floor washing via manual bucketing. The second system consisted of diverting

greywater generated by the premises for gravity fed sub-surface irrigation. The third,

consisted of a commercially available state-of-the-art greywater recycling apparatus

composed of a single wash basin and toilet unit linked together to treat greywater

produced at the lavatory for toilet flushing. The last made use of commercially available

greywater treatment units for three types of greywater demands:




In order to compare results with rainwater harvesting systems, the same set of scenarios

were considered for evaluating the performance of greywater recycling systems. The

first, consisted of baseline water end-use consumption from mean values collected

during fieldwork, and the second, consisted of evaluating the performance of greywater

recycling using reduced water end-use consumption values obtained from water

efficient strategies in the home (Table 6.6).


Typological characteristics of built form, built area, plot size and typical water and

waste pipe installations from the different representative models were used as a basis for


230

hypothetical configurations of greywater recycling systems for the high, mid-high, mid-

low and low income dwelling typologies.

Due to the fact that the greywater collection pipework must be segregated from

blackwater drainage pipes, this study analysed the typical wastewater plumbing

installations for the different building typologies in order to appraise the possibility of

adapting the existing plumbing system for greywater collection.

Three different types of bathroom wastewater drainage pipework configuration were

found. The first was composed by separate drainage systems, which contained distinct

greywater and blackwater discharge pipes which met at an inspection chamber located

outside the residential building. The other two were composed of combined wastewater

discharge pipework, either with an outdoor connection or an indoor connection of

greywater pipes with blackwater pipes prior an inspection chamber located outside the

residential building.

In house dwellings, both greywater and black water pipes are commonly located inside

floor slabs, therefore, it would be necessary to break part of the floor slab to have access

to the existing discharge pipework in order to adapt and install separate lines of

collection pipework. This operation would lead to the redecoration of bathroom floors

and would present some level of inconvenience to residents.

In flat dwellings, greywater and blackwater pipes are commonly located under the floor

slab; hence, the adaptation of the existing discharge pipework would have to be carried

out at a lower level, at a downstairs neighbour bathroom. Furthermore, multi-storey flat

buildings contain a single stack pipe for vertical drainage of bathroom wastewater, and

as a result, a new stack system would need to be installed to transport greywater to the

ground level. Although recently built multi-storey buildings contain installation shafts,

which could facilitate adaptation, a major refurbishment to existing installations would

still be necessary, which would result in a high level of inconvenience to residents.

Both separate bathroom wastewater drainage systems and outdoor connection discharge

systems, proved to be of simple adaptation to the existing bathroom wastewater service

from house dwellings for greywater collection from lavatories and showers. The

adaptation of both drainage systems could be carried outside the building, before the


231

pipes reach the inspection chamber. A diversion of the greywater to a new drainage line

destined solely for greywater collection would be necessary. Such approach would

require a low level refurbishment, with minor or no redecoration, hence, promoting little


In Brazil, utility areas in house dwellings are commonly located next to the kitchens;

hence it is likely to find a combined wastewater pipework with an outdoor connection

of laundry water with kitchen sink water prior an inspection chamber. In multi-storey

flat dwellings, kitchen and utility sometimes share the same space inside the home; even

though, most buildings contain two distinct stack systems to transport laundry water

separately from the kitchen sink water to ground level. Since wastewater from kitchen

sinks and dishwashers contain grease, oil and organic matter, a grease trap box at

ground level prior to an inspection chamber is used to avoid the clogging of the

drainage system. Similarly, wastewater from washing machines and utility laundry

basins contain an antifoam box at ground level before it reaches the inspection chamber.

Plumbing adaptation for both houses and multi-storey flat buildings would require

disconnecting laundry pipework from the kitchen pipework and divert the laundry water

to a new drainage line for greywater collection. Such plumbing adaptation was

considered a simple and effective approach, leading to little or no inconvenience to

residents.

Combined wastewater discharge pipework with indoor connection of greywater pipes to

blackwater pipes from bathrooms, proved to be an unviable option due to the high costs

involved in refurbishment for building adaptation as well as being inconvenient to

residents. Therefore, this investigation focused on a more realistic approach, through the

adaptation of the existing wastewater network through the diversion of greywater pipes

before they reach the inspection chamber at ground level, outside the home, resulting in

a low level of refurbishment and promoting little inconvenience to residents.

Only greywater from utility faucets and washing machines were considered as viable

sources of greywater supply for multi-storey flat buildings. Since bathroom greywater

and blackwater from multi-storey flat buildings commonly shared the same stack

system, greywater from bathroom faucets and shower heads were not considered as

viable sources of greywater for reuse. However, due to the fact that most multi-storey


232

flat buildings contained a separate stack system to transport laundry wastewater from

kitchen wastewater to ground level, the diversion of greywater pipes from utility faucets

and washing machines prior connection with kitchen wastewater or inspection chamber,

was considered a viable alternative given that this approach required little adaptation to

existing plumbing installation and rendered little inconvenience to residents.

It is important to highlight the fact that most multi-storey flat buildings contained in

average four individual stack systems to transport laundry greywater to the ground

level. Therefore, not all laundry greywater had to be used. The fact that a multi-storey

flat building contained four segregated stacks for laundry greywater, allowed the use of

the necessary number of stacks to provide enough volume of greywater supply for a

determined demand, reducing refurbishment costs for plumbing modifications at ground

level.

Greywater collection from butt systems for manual bucketing required no building

adaptation. Laundry greywater from washing machines could be fed directly to a 300

litre storage tank placed next to the appliance through the washing machines’ discharge

hose. Such system was considered ineffective for multi-storey flat dwellings, since

outdoor water consumption was for communal garden irrigation and floor washing.

Outdoor distribution for greywater reuse could be done independently from existing

pipes, either through the use of gravity-fed diversion systems for subsurface irrigation,

or directly fed for irrigation or floor washing through water pump. Similar to non-

potable rainwater harvesting systems, indoor greywater distribution consisted in

modifying the existing header pipework layout at loft level, using the existing vertical

distributing pipes that only feed non-potable end-uses to supply treated greywater to

high pressure flush valves, utility faucets and washing machines.

The application of greywater diversion systems required irrigation trenches for sub-

surface irrigation and were only feasible for high-income houses, since the average mid-

low and low income houses contained cemented yards and no vegetated garden.

Although multi-storey flat buildings contained communal gardens, the amount of

greywater produced by flat dwellings on a daily basis was considered excessive for

adequate ground seepage, and therefore was discarded from analysis.


233


Domestic water reductions of the three different greywater demands described above

were estimated for the different dwelling typologies according to two scenarios: (i)

baseline water end-use consumption and (ii) reduced water end-use consumption. The

first, considered current domestic water end-use consumption, and the latter, considered

the possibility of achieving high water efficiency through the use of effective water

efficient strategies in combination with greywater recycling systems, resulting in a

reduced greywater supply and demand.

Daily greywater supply and demand for the baseline water end-use consumption

scenario were established for the different income typologies according to mean values

obtained from during water auditing. On the other hand, daily greywater supply and

demand for the reduced water end-use consumption scenario, were established

according to results previously obtained through the use of the most effective water

efficient strategies for the high, mid-high, mid-low and low income dwellings (Table

6.6).

Greywater supply for manual bucketing from greywater butt was established according

to the estimated daily average greywater generated from washing machines, while

greywater sources for diversion systems were estimated according to baseline water

demand. Considering the fact that the reduced water end-use consumption scenario

makes use of pressure washers and automatic surface irrigation systems, greywater butt

for manual bucketing and greywater diversion for sub-surface irrigation were not

conceived as adequate alternatives for such scenario.

As for greywater treatment systems, a balance between greywater demand and supply

was sought for the different types of reuse in the attempt to equalise the volume of

greywater available for treatment with the volume of greywater required to meet

demand. Tables 6.23 and 6.24 summarizes the daily volume of greywater generated to

supply different daily greywater demands per income building typology for both

baseline and reduced water end-use consumption scenarios.

The selection of greywater sources was carried out considering the level of

refurbishment required to adapt the existing building typology for greywater collection,

and treatment cost. This study focused on the application of commercially available


234

greywater treatment units. The greywater treatment units were selected according to the

volumes of greywater to be treated, since commercially available treatment units are

sold in pre-determined ranges of treatable greywater volume.

Overall, water savings for greywater recycling systems were estimated according to the

balance of greywater supply and demand. When greywater supply was greater than

demand, water savings was estimated according to the daily volume of greywater

demand. However, when greywater supply was insufficient to meet demand, water

savings was estimated according to the daily volume of greywater supply.


235

Table 6.23 Baseline water end-use consumption scenario for greywater demand and supply according to different types of reuse HIGH INCOME MID-HIGH INCOME MID-LOW INCOME LOW INCOME

Greywater Demand Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3

Toilet Flush (litre/day) --- 169 169 --- 7,504 7,504 --- 133 133 --- 94 94 Utility Faucet (litre/day) --- --- 92 --- --- 2,338 --- --- 70 --- --- 52 Washing Machine (litre/day) --- --- 138 --- --- 5,266 --- --- 123 --- --- 87 External Tap (litre/day) 236 236 236 524 524 524 53 53 53 43 43 43 TOTAL 236 405 635 524 8,028 15,632 53 186 378 43 137 276

Greywater Supply Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3

Bathroom Faucet (litre/day) --- 74 74 --- --- --- --- --- 51 --- --- 65 Shower Head (litre/day) --- 145 145 --- --- --- --- --- 164 --- --- 140 Utility Faucet (litre/day) 92 92 92 1,169 2,338 2,338 70 70 70 52 52 52 Washing Machine (litre/day) 138 138 138 2,633 5,266 10,531 123 123 123 87 87 87 TOTAL 230 449 449 3,802 7,604 12,869 192 192 408 139 139 344

Table 6.24 Reduced water end-use consumption scenario for greywater demand and supply according to different types of reuse

HIGH INCOME MID-HIGH INCOME MID-LOW INCOME LOW INCOME

Greywater Demand Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3

Toilet Flush (litre/day) --- 67 67 --- 3,152 3,152 --- 58 58 --- 45 45 Utility Faucet (litre/day) --- --- 77 --- --- 3,788 --- --- 65 --- --- 52 Washing Machine (litre/day) --- --- 74 --- --- 4,844 --- --- 60 --- --- 40 External Tap (litre/day) 55 55 55 123 123 123 33 33 33 29 29 29 TOTAL 55 123 274 123 3,275 11,907 33 91 216 29 74 166

Greywater Supply Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3 Reuse 1 Reuse 2 Reuse 3

Bathroom Faucet (litre/day) --- 22 22 --- --- --- --- --- 15 --- --- 19 Shower Head (litre/day) --- 120 120 --- --- --- --- --- 142 --- --- 140 Utility Faucet (litre/day) 77 77 77 947 1,894 3,788 65 65 65 52 52 52 Washing Machine (litre/day) 74 74 74 1,211 2,422 4,844 60 60 60 40 40 40 TOTAL 151 293 293 2,158 4,316 8,632 125 125 283 92 92 252


236

Greywater collection could be carried out by adapting laundry and bathroom discharge

pipework. Selecting laundry discharge pipework for greywater supply consisted in

quantifying the average daily consumption from both utility faucet and washing

machine, and selecting bathroom greywater discharge for supply consisted in

considering the average daily consumption from bathroom faucets and shower heads.

In order to quantify greywater supply for residential multi-storey flat buildings, it was

important to consider the fact that not all laundry greywater stack systems would have

to be used. As seen in the previous section, multi-storey flat buildings commonly

comprise of four laundry greywater stack systems, and that plumbing adaptations could

be done at ground level. Therefore, in order to quantify greywater supply for multi-

storey flat buildings, the volume of greywater discharged per stack system was

considered in order to reduce refurbishment and costs with greywater treatment units.

Table 6.25 Annual domestic water savings promoted by greywater recycling systems

for different income typologies in baseline and reduced water end-use consumption

scenarios

Greywater Recycling System


Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

High Income Dwellings

Greywater Butt for Manual Bucketing 50 9.5 --- --- Greywater Diversion System 84 15.8 --- --- Greywater Reuse Toilet & Lavatory Unit 27 0.1 8 64.7 Greywater Treatment System - Reuse 1 84 15.8 20 67.0 Greywater Treatment System - Reuse 2 148 27.8 45 71.6 Greywater Treatment System - Reuse 3 164 30.8 107 83.3

Mid-High Income Dwellings

Greywater Reuse Toilet & Lavatory Unit 23 9.4 6 44.8 Greywater Treatment System - Reuse 1 3 1.1 1 42.5 Greywater Treatment System - Reuse 2 39 15.8 17 49.1 Greywater Treatment System - Reuse 3 65 26.7 60 67.0

Mid-Low Income Dwellings

Greywater Butt for Manual Bucketing 19 6.9 --- --- Greywater Reuse Toilet & Lavatory Unit 19 6.6 15 42.6 Greywater Treatment System - Reuse 1 19 6.9 12 41.5 Greywater Treatment System - Reuse 2 68 24.1 33 49.0 Greywater Treatment System - Reuse 3 149 52.9 103 73.9

Low Income Dwellings

Greywater Butt for Manual Bucketing 16 6.8 --- --- Greywater Reuse Toilet & Lavatory Unit 24 3.1 7 39.5 Greywater Treatment System - Reuse 1 16 6.8 11 41.1 Greywater Treatment System - Reuse 2 50 21.7 27 48.1 Greywater Treatment System - Reuse 3 126 54.2 92 76.2


237

Table 6.25 summarizes the results of annual water savings per dwelling of the varied

greywater recycling systems for the different income dwellings, and their water

reduction index (WRI) achieved according to baseline and reduced end-use

consumption scenarios. Similar to rainwater harvesting systems, higher annual water

saving figures were obtained for the baseline water end-use consumption scenario than

for the reduced water end-use consumption scenario. However, water reduction indexes

proved to be more effective when the greywater recycling systems were used in

combination with water efficient strategies. Overall, dealing with the same values of

baseline water demands, greywater butt for manual bucketing presented equivalent

figures of domestic water reductions as greywater treatment system for irrigation and

floor washing (Reuse 1).

Although the baseline scenario presented higher rates of water savings for high income

dwellings, ranging from 50m3/dw/yr, through the use of greywater butt for manual

bucketing, to 164m3/dw/yr, through the use of greywater treatment system for irrigation,

floor washing, toilet flushing and clothes washing (Reuse 3), the reduced scenario

presented higher water reduction indexes. The lowest water reduction index for the

reduced scenario (64.7%) was more than twice the highest estimated water reduction

index of the baseline water end-use consumption scenario (30.8%). Potentially,

domestic water reductions could reach up to 83.3%, through the combination of water

efficient strategies and the use of greywater recycling systems for irrigation, floor

washing, toilet flushing and clothes washing (Reuse 3).

Mid-high income flat dwellings presented the lowest rates of domestic water reductions

through the use of greywater treatment systems for communal outdoor water end-uses

(Reuse 1). The highest rates of domestic water savings for mid-high income flat

dwellings were obtained through the use of a greywater treatment system – Reuse 1, for

both baseline and reduced water end-use consumption scenario’s (65m3/dw/yr and

60m3/dw/yr, respectively).

Water savings for mid-low income house dwellings ranged from 12m3/dw/yr, using

greywater treatment system for a reduced outdoor (Reuse 1) water end-use consumption

scenario, to 149m3/dw/yr, using a greywater treatment system (Reuse 3) at a baseline

water end-use consumption scenario. The use of a greywater treatment system for floor

washing, toilet flushing and clothes washing (Reuse 3) in combination with water


238

efficient strategies, proved to be the most effective measure, with a water reduction

index of 73.9%.

Although baseline water end-use consumption scenario for low income dwellings

presented water reduction indexes ranging from 6.8% (16m3/dw/yr), with greywater

butt for manual bucketing and greywater treatment system – Reuse 1, to 54.2%

(126m3/dw/yr) using greywater treatment system – Reuse 3, the reduced water end-use

consumption scenario presented water reduction indexes ranging from 39.5%

(7m3/dw/yr) with the greywater reuse toilet and lavatory unit, to 76.2% (92m3/dw/yr)

using a greywater treatment system – Reuse 3, in combination with water efficient

strategies.


The economic assessment of greywater recycling systems for high, mid-high, mid-low

and low income dwellings was carried out using simple payback period, life cycle cost-

benefit analysis and average incremental cost for baseline and reduced water end-use

consumption scenario’s (see Tables 6.26 to 6.33 for a summary of results). Appendix O

summarizes the estimated capital costs and operational costs used for the cost-benefit

analyses of greywater recycling systems.

Overall, the great majority of greywater recycling systems for both baseline and reduced

water consumption scenario’s presented a capital cost superior to resident’s willingness-

to-pay for water conservation measures. However, results showed that the capital cost of

a greywater butt for manual bucketing for baseline water end-use consumption was

lower than high income resident’s willingness-to-pay, indicating that resident’s would

invest in such system. Furthermore, such option contained a payback period much lower

than that expected from high income residents.

Greywater treatment system for garden irrigation and floor washing (Reuse 1) also

contained a lower capital cost than mid-high income resident’s willingness-to-pay.

Since the capital cost of greywater treatment system for irrigation, floor washing and

toilet flushing (Reuse 2) for baseline water end-use consumption was slightly higher

than mid-high income resident’s willingness-to-pay, it might also be considered as an

option flat resident’s would be willing to invest for financial benefits. However,

considering residents’ expectations regarding the payback period of an investment, only


239

the greywater treatment system – Reuse 2, might be considered if residents would be

willing to extend the period of investment return to an extra 5 months.

The financial benefits from greywater recycling systems during their useful life was

analysed for the different income dwellings. Considering the benefits gained during its

life cycle, greywater butt for manual bucketing proved to be a feasible option for high

(R$7,766.58), mid-low (R$1,713.53) and low (R$1,054.30) income dwellings.

Moreover, the payback period was of less than one year. The diversion of greywater for

sub-surface irrigation could only be applied to high income dwellings, leading to a

profit of R$7,845.50 during its useful life.

Greywater treatment systems proved to be the most effective greywater recycling

systems for mid-high income dwellings. While the greywater treatment system for

irrigation, floor washing and toilet flushing for both baseline (Reuse 2) resulted in a

financial return of R$2,549.45 during the system’s estimated life expectancy, with a

payback period of 2.4 years, greywater systems for irrigation, floor washing, toilet

flushing and clothes washing (Reuse 3) proved to be more feasible for the baseline

scenario (R$4,842.32) and a payback period of 1.4 year, than for the reduced scenario

(R$379.65), mainly due to the high costs involved in using both water efficient

strategies and greywater recycling systems in combination.

The average incremental cost for these feasible greywater recycling systems was

calculated within a timeframe of 30 years. Overall, the rates of financial return of

greywater butt for manual bucketing for baseline water end-use consumption were

equivalent to 5.15 R$/m3 for high income dwellings, 2.96 R$/m3 for mid-low income

dwellings and 2.24 R$/m3 for low income dwellings. While the rate of financial return

for the greywater treatment system – Reuse 2 for mid-high income dwellings was

equivalent to 2.20 R$/m3, rates of return for the greywater treatment systems for

irrigation, floor washing, toilet flushing and clothes washing, was equivalent to 2.47

R$/m3 (baseline scenario) and 0.21 R$/m3 (reduced scenario).


240

Table 6.26 Cost-benefit analyses of greywater recycling systems on a baseline water end-use scenario for high income dwellings

Water Effcient Strategies Water Savings

(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Butt for Manual Bucketing 50 401.08 94.70 0.00 0.2 30 7,766.58 5.15

Greywater Diversion System 84 670.07 5,288.13 0.00 7.9 30 7,845.50 3.11

Greywater Toilet & Lavatory Unit 27 214.63 84,000.00 360.00 31 23 -86,390.41 -107.59

Greywater Treatment System - Reuse 1 84 670.07 5,477.45 458.38 25.9 30 -2,712.77 -1.08

Greywater Treatment System - Reuse 2 148 1,178.25 21,257.80 910.95 80 30 -17,403.06 -3.93

Greywater Treatment System - Reuse 3 164 1,306.61 21,321.25 927.15 56 30 -15,268.14 -3.11

Table 6.27 Cost-benefit analyses of greywater recycling systems on a reduced water end-use scenario for high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Toilet & Lavatory Unit 8 64.39 93,983.73 360.00 1,100 23 -98,844.64 -408.18

Greywater Treatment System - Reuse 1 20 161.47 15,461.18 508.38 * 30 --- ---

Greywater Treatment System - Reuse 2 45 357.93 31,241.53 910.95 * 30 --- ---

Greywater Treatment System - Reuse 3 107 854.42 31,304.98 927.15 * 30 --- --- * Operational costs overcome financial benefits.


241

Table 6.28 Cost-benefit analyses of greywater recycling systems on a baseline water end-use scenario for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Toilet & Lavatory Unit 23 100.71 42,000.00 180.00 417.0 23 -62.59 -124.55

Greywater Treatment System - Reuse 1 2.7 11.68 265.67 7.91 70.6 30 -197.43 -2.48

Greywater Treatment System - Reuse 2 38.5 169.55 361.86 19.90 2.4 30 2,549.45 2.20

Greywater Treatment System - Reuse 3 65.2 286.96 370.30 19.90 1.4 30 4,842.32 2.47

Table 6.29 Cost-benefit analyses of greywater recycling systems on a reduced water end-use scenario for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Toilet & Lavatory Unit 6 27.19 46,042.13 180.00 * 23 --- ---

Greywater Treatment System - Reuse 1 0.6 2.74 4,307.80 7.91 * 30 --- ---

Greywater Treatment System - Reuse 2 16.6 73.02 4,403.99 19.90 82.9 30 -3,384.66 -6.80

Greywater Treatment System - Reuse 3 60.4 265.51 4,412.43 19.90 18.0 30 379.65 0.21 * Operational costs overcome financial benefits.


242

Table 6.30 Cost-benefit analyses of greywater recycling systems on a baseline water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Butt for Manual Bucketing 19.3 92.25 94.70 0.00 1.0 30 1,713.53 2.96

Greywater Toilet & Lavatory Unit 18.6 89.11 42000.00 180.00 * 23 --- ---



Greywater Treatment System - Reuse 3 148.8 711.65 20,543.75 927.15 * 30 --- --- * Operational costs overcome financial benefits.

Table 6.31 Cost-benefit analyses of greywater recycling systems on a reduced water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Toilet & Lavatory Unit 15.3 73.24 47790.13 180.00 * --- --- ---

Greywater Treatment System - Reuse 1 12.1 57.66 10,013.78 408.38 * --- --- ---

Greywater Treatment System - Reuse 2 33.2 158.57 26,270.43 927.15 * --- --- ---

Greywater Treatment System - Reuse 3 103.3 493.92 26,333.88 927.15 * --- --- --- * Operational costs overcome financial benefits.


243

Table 6.32 Cost-benefit analyses of greywater recycling systems on a baseline water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Butt for Manual Bucketing 15.7 58.62 94.70 0.00 1.6 30 1,054.30 2.24

Greywater Toilet & Lavatory Unit 23.6 88.06 28,000.00 120.00 * 23 --- ---




Table 6.33 Cost-benefit analyses of greywater recycling systems on a reduced water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Greywater Toilet & Lavatory Unit 7.1 26.42 32550.96 120.00 * 30 --- ---





244

6.6 Wastewater Reclamation Systems

The same representative models composed to evaluate rainwater harvesting and

greywater recycling systems, were used to evaluate the viability of wastewater

reclamation systems in terms of their applicability, domestic water reductions and cost-

benefits. As previously seen in Chapter 4, two different types of treated wastewater

demands were derived for analysis:



Both baseline water end-use consumption and reduced water consumption scenarios

were used as a basis for evaluating the performance of wastewater reclamation system

individually, or in combination with water efficient strategies in the home. For baseline

and reduced water end-use consumption scenarios, wastewater demand and supply was

carried out according to Table 6.6.

To avoid risks related with water reuse quality standards, this study focused on the use

of commercially available wastewater reclamation units. Hence, wastewater treatment

units were selected according to the volumes of wastewater to be treated, since

commercially available treatment units are sold in pre-determined ranges of treatable

wastewater volume.


The same typological characteristics of built form, built area, plot size and typical water

and waste pipe installations from the different representative models were used as a

basis for a hypothetical configuration of wastewater reclamation systems for the high,

mid-high, mid-low and low income dwelling typologies.

Wastewater collection for both houses and multi-storey buildings would require little

refurbishment to their existing wastewater discharge network, due to the fact that

wastewater reclamation systems make use of both greywater and black water for

biological treatment. The installation of the wastewater reclamation unit would be

carried out at ground level, using the existing wastewater drainage system, collecting

the building’s wastewater before it reached the authority sewer collection system. Such


245

plumbing adaptation was considered simple and effective, with little or no


After receiving an adequate level of treatment for reuse, outdoor distribution of

reclaimed wastewater for irrigation and floor washing could be carried out

independently from the existing pipework through the use of a water pump. Similarly to

both non-potable rainwater harvesting system and greywater recycling system, indoor

distribution of reclaimed wastewater would require modifications to the existing header

pipework layout at loft level, using existing vertical distributing pipes which feed high

pressure flush valves.


Water savings for wastewater reclamation systems were determined according to the

volume of daily reclaimed wastewater demand. Table 6.34 presents the domestic water

reductions promoted by the wastewater reclamation systems for the different income

typologies in baseline and reduced water end-use consumption scenarios.

Table 6.34 Domestic water reductions promoted by wastewater reclamation systems for

different income typologies in baseline and reduced water end-use consumption

scenarios

Wastewater Reclamation System


Water Savings (m

3/dw/yr)

WRI (%)

Water Savings (m

3/dw/yr)

WRI (%)

High Income Dwellings

Wastewater Treatment System - Reuse 1 86 16.2 20 67.0 Wastewater Treatment System - Reuse 2 148 27.8 45 71.6

Mid-High Income Dwellings

Wastewater Treatment System - Reuse 1 3 1.1 0.6 42.9 Wastewater Treatment System - Reuse 2 41 16.7 17 58.9

Mid-Low Income Dwellings


Low Income Dwellings


As expected, higher levels of domestic water reductions were obtained by using

wastewater treatment systems for irrigation, floor washing and toilet flushing (Reuse 2),

than for irrigation and floor washing (Reuse 1). Similar to both rainwater harvesting

systems and greywater recycling systems, water savings were higher for the baseline


246

scenario; however, the reduced water end-use scenario presented higher figures of water

reduction index when wastewater reclamation systems were used in combination with

water efficient strategies.

The highest water reduction index obtained for high income dwellings was 71.6%

through the use of wastewater treatment system – Reuse 2, in combination with water

efficient strategies, and the lowest, was equivalent to 16.2% the use of wastewater

treatment system for baseline water end-use consumption.

Mid-high income dwellings presented the lowest water reduction indexes for both

wastewater treatment systems (1.1% and 16.7%) at the baseline water end-use

consumption scenario. At a reduced water end-use scenario, water reductions reached to

maximum 58.9%.

Mid-low income dwellings presented water reduction indexes ranging from 6.9% using

a wastewater treatment system for outdoor baseline water end-use consumption, to

49.0%, through the application of wastewater treatment systems for both reduced

outdoor end-uses and toilet flushing.

The lowest water reduction indexes for low income dwellings were equivalent to 6.8%

through the use of wastewater treatment systems for floor washing (Reuse 1) and 21.1%

using a wastewater treatment system for floor washing and toilet flushing, at baseline

level. The highest water reduction indexes were registered using wastewater treatment

systems in a reduced water end-use consumption scenario for floor washing only

(41.1%), and both floor washing and toilet flushing (48.1%).


Simple payback period, life cycle cost-benefit analysis and average incremental cost

methods of financial evaluation were used to assess the feasibility of wastewater

reclamation systems using both baseline and reduced water consumption scenario’s for

high, mid-high, mid-low and low income dwellings (see Tables 6.35 to 6.42 for a

summary of results). Appendix P summarizes the estimated capital costs and

operational costs used for the cost-benefit analyses of wastewater reclamation systems.


247

On the whole, capital costs of wastewater reclamation systems for both baseline and

reduced water consumption scenario’s were greater than resident’s willingness-to-pay.

However, wastewater treatment system for garden irrigation and floor washing (Reuse

1) have a lower capital cost than mid-high income resident’s willingness-to-pay. Since

the capital cost of greywater treatment system for irrigation, floor washing and toilet

flushing (Reuse 2) for baseline water end-use consumption was slightly higher than

mid-high income resident’s willingness-to-pay, it might also be considered as an option

flat resident’s would be willing to invest for financial benefits. However, considering

residents’ expectations regarding the payback period of an investment, only the

greywater treatment system – Reuse 2, might be considered if residents would be

willing to extend the period of investment return to an extra 5 months.

The payback analysis shows that only the wastewater treatment system (reuse 2) on

base line scenario for the mid-high income is a viable option. For the other options it

has shown that operational costs were higher than the financial benefits.

The financial benefits during a wastewater reclamation system’s life expectancy was

evaluated for the different income dwellings using both baseline and reduced water end-

use consumption scenarios. Overall, the lifecycle analysis has shown that only the

wastewater treatment system for irrigation, floor washing and toilet flushing on a

baseline water end-use consumption scenario was considered to be a feasible option for

mid-high income dwellings, providing a financial return of R$2,716.31. Using a time

horizon of 30 years, the average incremental cost of such wastewater reclamation

system was equivalent to R$2.22 per cubic meter of water saved.


248

Table 6.35 Cost-benefit analyses of wastewater reclamation systems on a baseline water end-use scenario for high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 86 687.12 20,343.75 508.38 113.8 30 -26,824.07 -10.38

Wastewater Treatment System - Reuse 2 148 1,178.25 22,487.60 508.38 33.6 30 -19,341.53 -4.36

Table 6.36 Cost-benefit analyses of wastewater reclamation systems on a reduced water end-use scenario for high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 20 161.47 30,327.48 508.38 * 30 --- ---

Wastewater Treatment System - Reuse 2 45 357.93 32,471.33 508.38 * 30 --- --- * Operational costs overcome financial benefits.

Table 6.37 Cost-benefit analyses of wastewater reclamation systems on a baseline water end-use scenario for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 2.7 11.68 272.15 12.42 * 30 --- ---

Wastewater Treatment System - Reuse 2 40.7 179.01 312.33 23.37 2.0 30 2,716.31 2.22 * Operational costs overcome financial benefits.


249

Table 6.38 Cost-benefit analyses of wastewater reclamation systems on a reduced water end-use scenario for mid-high income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 0.6 4.98 4,314.28 12.42 * 30 --- ---

Wastewater Treatment System - Reuse 2 16.6 132.43 4,354.46 23.37 39.9 30 -2,238.79 -4.50 * Operational costs overcome financial benefits.

Table 6.39 Cost-benefit analyses of wastewater reclamation systems on a baseline water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 19 92.25 20,343.75 927.15 * --- --- ---

Wastewater Treatment System - Reuse 2 68 324.30 22,487.60 927.15 * --- --- --- * Operational costs overcome financial benefits.

Table 6.40 Cost-benefit analyses of wastewater reclamation systems on a reduced water end-use scenario for mid-low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)

Wastewater Treatment System - Reuse 1 12 57.66 26,133.88 927.15 * --- --- ---

Wastewater Treatment System - Reuse 2 33 158.57 28,277.73 927.15 * --- --- --- * Operational costs overcome financial benefits.


250

Table 6.41 Cost-benefit analyses of wastewater reclamation systems on a baseline water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)



Table 6.42 Cost-benefit analyses of wastewater reclamation systems on a reduced water end-use scenario for low income dwellings


(m3/dw/yr)

Financial

Benefits (R$/dw/yr)


Operational

Cost (R$/dw/yr)

Simple

Payback (yr)

Average Life

Expectancy (yr)

LCCB (R$)

AIC (R$/m

3)




251

6.7 Summary and Conclusions

In order to identify feasible water conservation measures in terms of their applicability,


typologies of the Federal District, four representative models were composed according

to the average values of the primary data for public opinion, awareness and acceptance

of water conservation strategies, water end-use consumption and dwelling

characteristics.

These models were used as a basis for evaluating the applicability of water conservation

measures according to public opinion, awareness and acceptance, and building

adaptation. Overall, respondents indicated that they are aware of the existence of water

conservation measures, and that they would be willing to retrofit their homes to reduce

their water consumption. However, results demonstrated that public willingness-to-pay

was low, and the great majority of respondents expected a low payback period for their

investment. Each representative model was also used in the hypothetical configuration

of water efficient equipment and water reuse systems, thus aiding in the estimation the

capital costs and operational costs of each water conservation measure.

Overall, dwelling retrofit for water efficient equipments proved to be of simple

installation, requiring little or no refurbishment for their application. Water reuse

systems on the other hand, required some level of building adaptation. Although the

distribution of treated water for non-potable outdoor end-uses was of simple

refurbishment, the distribution of treated water for indoor end-uses required a higher

level of refurbishment via header pipework adaptation on buildings with single vertical

distribution pipes that solely feed non-potable end-uses. Apart from residential flat

buildings, rainwater harvesting systems required the installation of a rainwater

collection and drainage network for building adaptation. Greywater recycling systems

on the other hand, required a distinct collection pipework. While greywater butts for

manual bucketing and the greywater reuse toilet & lavatory units required no

refurbishment, the application of greywater diversion systems required irrigation

trenches for sub-surface irrigation. Wastewater collection for both houses and multi-

storey buildings would require little refurbishment to their existing wastewater


252

discharge network, since wastewater reclamation systems treat both greywater and

black water for reuse.

Domestic water reductions were estimated for every water conservation measure.

Overall, water reuse systems were capable of promoting higher water reductions than

water efficient strategies. The upper limit of achievable water reductions through the

use of the most effective water efficient strategies was verified, and with this, a reduced

water end-use consumption scenario was created, considering the possibility of using

effective water efficient strategies in combination with water reuse systems. As

expected, higher domestic water reductions were achieved through the use of water

reuse systems in combination with water efficient strategies.

The financial benefit promoted by each water conservation measure was evaluated

using simple payback period, life cycle cost-benefit analysis and average incremental

costs. Results indicated that simple, low budget water conservation measures were

capable of achieving the highest rate of financial benefit per volume of water saved.

Table 6.43 on the next page provides an overview of the feasible water conservation

measures for the different income ranges. Domestic water efficiency proved to be the

most viable solution for reducing water consumption, independent of the income level

and building typology. On one hand, simple, small scale water reuse systems proved to

be feasible options for investment on house dwellings – especially greywater butt for

manual bucketing. On the other hand, the use of greywater and wastewater treatment

systems proved to be feasible options for densely populated multi-storey buildings.


253

Table 6.43 Feasible water conservation measures for the different income ranges


HI MHI MLI LI

WRI AIC WRI AIC WRI AIC WRI AIC

(%) (R$/m3) (%) (R$/m

3) (%) (R$/m

3) (%) (R$/m

3)

Water Efficient Fittings, Fixtures and Appliances

Bathroom Faucet Flow Regulator 3.2 4.74 6.9 2.69 4.3 2.24 6.4 1.78

Low-Flush Toilet (6 lpf) 3.9 4.47 5.2 1.68 5.7 2.15 5.0 1.61

Dual Flush Toilet (3/6 lpf) 6.9 3.71 9.0 0.37 9.7 1.61 7.8 1.03

Kitchen Sensor Faucet 3.8 3.24 6.1 0.20 7.5 1.89 7.0 1.23

Kitchen Faucet Flow Regulator 2.9 5.13 4.1 2.75 6.3 2.35 6.7 1.83

Utility Faucet Flow Regulator 1.1 4.99 1.8 2.60 0.6 1.99 --- ---

High-Efficiency Washing Machine --- --- --- --- 36.5 0.65 33.1 0.11

Automatic Shut-off Hose Nozzle 1.2 3.42 --- --- 0.5 0.30 0.5 0.04

Pressure Washer 10.4 3.86 0.7 2.87 --- --- --- ---

Automatic Irrigation Sprinkler System --- --- 0.1 0.57 --- --- --- ---

Leakage Repair 7.4 5.13 --- --- 0.3 1.30 4.1 2.30

Rainwater Harvesting Systems for Baseline Consumption

1m3 Rainwater Cistern - Reuse 1 11.0 2.91 0.7 1.11 --- --- --- ---



15m3 Rainwater Cistern - Reuse 1 --- --- 0.9 0.10 --- --- --- ---

5m3 Rainwater Cistern - Reuse 2 19.4 0.16 --- --- --- --- --- ---






Greywater Recycling Systems for Baseline Consumption

300L Greywater Butt for Manual Bucketing 9.5 5.15 --- --- 6.9 2.96 6.8 2.24

Greywater Diversion for Subsurface Irrigation 15.8 3.11 --- --- --- --- --- ---

Greywater Recycling Systems for Reduced Consumption

Greywater Treatment System - Reuse 3 --- --- 67.0 0.21 --- --- --- ---

Wastewater Reclamation Systems for Reduced Consumption

Wastewater Treatment System - Reuse 2 --- --- 16.7 2.22 --- --- --- ---

Chapter 7 Conclusions and Recommendations

Conclusions and Recommendations

255

7. Conclusions and Recommendations

7.1 Introduction

This research arose from the need to reduce domestic water consumption in the Federal

District in a viable and cost-effective manner, so as to avoid water stress and promote

sustainable development through water demand management. Little is known about the

feasibility of domestic water conservation measures for Federal District and for Brazil.

Moreover, there is no information on domestic water consumption of dwellings from

different income groups and residential typologies in the Federal District to adequately

assess the feasibility of these water conservation measures. Therefore, the overall aim of

this thesis was to provide specific information regarding domestic water consumption

and assess the feasibility of domestic water conservation measures for the Federal

District’s dwellings of different incomes and residential typologies.

This chapter presents the findings of the research and its main arguments and

conclusions. Next, it outlines the main contributions to knowledge, looks into the

limitations of the research, and lastly, it provides some recommendations for further

work and some implications of the findings.

7.2 Domestic water consumption

This research uses both quantitative and qualitative methodological approaches to

collect primary data on domestic water consumption. The first, involved a face-to-face

questionnaire survey that gathered data on dwelling characteristics over a stratified

random sample size of 481 dwellings. The second, involved an in-depth analysis of

domestic water end-use consumption using a questionnaire designed to understand

resident’s water-consuming habits and, through a water auditing technique, it measures

domestic water end-use consumption for another 117 dwellings.

The basic hypothesis is that variables such as household income, dwelling typology and

occupant behaviour affects the way water is used. Primary data on annual, monthly,

weekly and daily baseline water consumption indicators was collected for high, mid-

high, mid-low and low income dwellings. Overall, results suggest that there is a positive

relationship between household income and domestic per capita water consumption,


256

where, the higher the income level, the higher the rate of per capita water consumption.

High income dwellings presented significantly higher per capita water consumption

when compared to the lower income ranges, suggesting that such outstanding difference

in consumption is caused by social inequality.

Even though every individual dwelling presents unique patterns of domestic water end-

use consumption, results obtained by water auditing are similar to previous studies

carried out in developing countries. Overall, showerheads, washing machines, toilet

flushes and kitchen faucets had the highest rates of indoor water end-use consumption.

Outdoor water end-use consumption for garden irrigation and floor washing represented

13% of total domestic water consumption, mostly from external taps.

Monthly precipitation and relative humidity were cross-referenced with the average

values of monthly water consumption gathered from historic billing data of the studied

dwellings. It was observed that low levels of precipitation and relative humidity caused

an increase in water consumption. However, seasonal variations in domestic water

consumption were mostly limited to high income dwellings, whose typological

characteristics included a large vegetated garden area.

Residential characteristics such as built type, built area, roof area, garden/yard size,

swimming pools and water fixtures and appliances in the homes were obtained from

both quantitative and qualitative questionnaires. Distinct dwelling characteristics and

typological composition per administrative region of the Federal District could be

found. This research found that the typological composition of dwellings was directly

related to income, where, the higher the income, the bigger the built area, veranda,

garden/yard, quantity and quality of fixtures and appliances, and presence of swimming

pools.

Results suggest that the typological composition of dwellings can influence the way

water is used by residents. For example, high income dwellings contained extra

bathroom fixtures, kitchen faucets and external taps. The wider the range of water

facilities available, the more opportunities residents have to use water. Furthermore,

larger gardens, verandas and the presence of swimming pools, lead to greater outdoor

water consumption.


257

Key elements of water usage were assessed through an in-depth analysis of water-

consuming activities in 117 homes to point out behavioural trends of water consumption

according to dwelling income and built type.

Results show that behavioural patterns of domestic water usage can also be affected by

the typological composition of dwellings in the Federal District and in Brazil; it is a

common habit to wash external grounds of homes such as verandas, yards and

pavements on a regular basis. Findings also suggest that it is a common practice for

Brazilian residents to wash their dishes by hands, controlling the faucet with running

water while washing and rinsing the dishes. No residents washed their dishes using a

plugged sink, which is a common practice in other countries. Such behavioural

differences might be linked to cultural values, custom and tradition, affecting the way

water is used.

This study has shown that domestic water consumption increases proportionally to the

increase in household income and that it a function of income, cost of water, household

size and typological characteristics of built area.

The correlation analysis shows that in one hand, indoor water consumption has a strong

relationship with built area, income, household size and the cost of water. On the other

hand, outdoor water consumption presented a strong relationship with garden/yard area,

income and cost of water. Through multiple regressions, indoor and outdoor water

consumption functions were estimated for the Federal District. Estimated water demand

functions have shown a strong relationship between water consumption and household

income, built area and number of residents.

Since the results show that demand for water is inelastic to its price, public perception

over the cost of water was analysed. Although the great majority of respondents believe

current tariff rates are high, observed water-consuming behaviour indicated otherwise. It

seems that resident’s opinion over cost of water is insufficient to modify their

behaviour.


258

The research has found that most of the water-saving attitudes that have already been

taken by residents were carried out through behavioural changes of water-consuming

habits. The great majority of respondents are rightful owners of their homes, and most

of them are willing to invest on water-saving equipments, such as efficient water

fittings, fixtures and appliances or water reuse systems, for their homes to obtain both

financial and environmental benefits.

Low-budget rainwater and greywater reuse schemes was commonly used by mid-low

and low income dwellings for irrigation and floor washing, suggesting that due to their

income, these households searched for alternative ways to reduce their water bills

through reuse. Our results suggest that the lower the household income, the lower mains

water consumption is, and the higher the usage of alternative sources of water supply

such as untreated rainwater and greywater.

One of the main conclusions drawn from this study is that variables of dwelling

characteristics, income and occupant behaviour are directly related and affect both

indoor and outdoor water consumption patterns, and therefore, should be considered for

adequate water demand predictions, reuse system design dimensioning and quantifying

potential water-savings from conservation measures.

7.3 Evaluation of domestic water conservation measures

Based on the primary data collected on public opinion, awareness and acceptance of

water conservation strategies, water end-use consumption and dwelling characteristics,

the study identifies feasible water conservation measures in terms of their applicability,


typologies of the Federal District.

The applicability of both demand-side and supply-side water conservation measures

were evaluated according to: (i) public opinion, awareness and acceptance, and (ii)

building adaptation.

Most respondents are aware of the existence of water efficient equipments and water

reuse systems, and would be willing to adapt their dwellings to reduce water


259

consumption. However, their willingness-to-pay is low, and the great majority of

residents expect to obtain fast financial benefits from their investments on water-saving

products.

The representative models, composed according to typological characteristics such as

built form, built area and typical plumbing installations for the different income

dwellings, were used as a basis for hypothetical configurations of water efficient

equipments and water reuse systems. Furthermore, these hypothetical configurations

were used to estimate capital costs and operational costs of every water conservation

measure.

Overall, water efficient equipments are of simple installation, rendering in little or no

refurbishment of existing dwellings for building adaptation. Apart from manual

bucketing of untreated greywater, the applicability of water reuse systems require some

level of refurbishment for building adaptation, dependent upon the type of system to be

applied and its expected non-potable end-uses.

Water reuse systems for non-potable outdoor water end-uses were found to be easily

adaptable to existing dwellings, and require lower levels of refurbishment than non-

potable indoor end-uses. Considering Federal District’s typical indirectly-fed mains

water supply system, a simple and effective way to adapt existing dwellings for non-

potable indoor water reuse was derived by modifying existing header pipework layout

at building loft level and using existing vertical distributing pipes destined to feed non-

potable end-uses, only.

Domestic water reductions were estimated for a range of water efficient strategies for

each income dwelling typology. The most effective water efficient strategy for high

income dwelling typologies was the pressure washer followed by leakage repair. The

use of high-efficiency washing machines and dual flush toilets proved to be the most

effective water efficient strategies for the mid-high, mid-low and low income dwelling

typologies.

The upper limit of achievable water reductions through the use of the most effective

water efficient strategies was verified for each income dwelling typology. With this, two


260

scenarios were used to estimate water reductions from water reuse systems: (i) baseline

water end-use consumption and (ii) reduced water end-use consumption. The first

considered current domestic water end-use consumption to estimate water savings. The

second, considered the use of effective water efficient strategies in combination with

water reuse systems, resulting in a reduced water demand.

In order to estimate domestic water reductions for rainwater harvesting systems, three

types of rainwater demands were considered for analysis:




Potential water reductions were estimated for a range of rainwater cistern storage

volumes. Overall, results indicated that higher water savings were obtained in the

baseline water end-use consumption scenario than for the reduced scenario when using

the same rainwater storage volumes. It was observed that annual water savings rose

proportionally to increase in storage volume, however, reductions stagnated once the

rainwater harvesting system achieved its ideal storage capacity. On the whole, houses

contained the necessary roof area to collect enough rainwater to supply demand

throughout the year. However, multi-storey flat buildings contained insufficient roof

area to collect enough rainwater to supply and its demand.

Domestic water reductions for four different types of greywater systems were estimated.

The first consisted in the manual bucketing of stored laundry greywater in a water butt.

The second, considered a gravity-fed greywater diversion system for sub-surface

irrigation. The third, in a state-of-the-art greywater reuse toilet and lavatory appliance

unit and the fourth, of commercially available greywater treatment units for reuse 1,

reuse 2 and reuse 3 of greywater demand.

Greywater treatment systems for irrigation, floor washing, toilet flushing and clothes

washing provided the highest rates of water reductions. On the other hand, greywater

reuse toilet and lavatory unit presented extremely low levels of water savings. While the

use of greywater butt for manual bucketing is limited to house dwellings, greywater


261

diversion systems were only possible in high income dwelling typologies which

contained sufficient vegetated garden areas.

Potential domestic water reductions from wastewater reclamation systems, two types of

wastewater demands were considered according to manufacturers’ recommendations,

reuse 1 and reuse 2.

Potential water reductions promoted by wastewater reclamation systems were similar to

those from greywater recycling, suggesting that both reuse systems were capable of

providing reclaimed water to fully supply non-potable end-uses.

Higher domestic water reductions were achieved through the combination of water

efficient strategies and water reuse systems. Overall, greywater recycling system for

irrigation, floor washing, toilet flushing, and clothes washing had the highest levels of

water reductions: 83% on high income dwelling typologies, 67% on mid-high income

dwelling typologies, 74% on mid-low income dwelling typologies and 76.2% on low

income dwelling typologies.

An economic assessment for the different water conservation measures was carried out

using simple payback period, life cycle cost-benefit analysis and average incremental

cost in order to identify economically viable options for the different income dwelling

typologies. The feasibility of the water conservation measures was evaluated according

resident willingness-to-pay and in general, findings suggest that simple, low budget

water conservation measures are capable of achieving the highest financial benefits per

volume of water saved.

Results from the economic assessment for water efficient strategies have shown that,

with very little investment, the use of flow regulators in faucets can provide dwellings

with significant financial benefits. Other economically viable water efficient strategies

include leakage repair, low-flush toilets, dual flush toilets, kitchen sensor faucets, high

efficiency washing machines, automatic shut-off hose nozzles, pressure washers, and

automatic irrigation sprinkler system (for mid-high income dwelling typologies only).


262

Results from the cost-benefit analyses suggest that the use of water reuse systems in

combination with water efficient strategies are economically viable solutions only for

dwellings with high consumption rates.

Economically viable water reuse systems for high income dwellings included rainwater

harvesting systems for reuse 1, reuse2 and reuse 3, greywater butt for manual bucketing

and greywater diversion system on baseline water consumption scenario. On the other

hand, economically viable water reuse systems for mid-high income dwelling

typologies included rainwater harvesting systems for reuse 1, greywater treatment

systems for Reuse 2 and Reuse 3 and wastewater treatment system for Reuse 2 on a

baseline consumption scenario. Economically viable water reuse systems for both mid-

low and low income dwelling typologies were limited to greywater butt for manual

bucketing only.

Another main conclusion derived of this study is that although water reuse systems are

capable of promoting higher water savings than water efficient strategies, water efficient

strategies proved to be the most feasible water conservation measures in terms of

applicability and financial benefits, independent of income level and dwelling typology.

7.4 Contribution to knowledge

This study represents the first attempt to explore the relationship between domestic

water consumption and dwelling typology, household income and occupant water use

behaviour in one of the most unequal cities in the world, and to adequately assess the

feasibility of a wide range of water conservation measures for Brazilian dwellings of

different incomes and residential typologies in terms of their applicability, water

savings and financial benefits.

Considering the primary contributions to the field of domestic water consumption, this

research has:

• Assessed current domestic water consumption and identified water end-use

patterns for the different income ranges and dwelling typologies in the Federal

District.


263

• Presented means for more accurate domestic water end-use predictions for the

different income groups and dwelling typologies in Brazil.

• Identified the key variables that affect both indoor and outdoor water

consumption in the Federal District and estimated regression models for water

demand predictions.

• Provided a better understanding of how variables of dwelling characteristics,

income and occupant behaviour are directly related and affect both indoor and

outdoor water consumption patterns.

• Offered a better understanding of the behavioural aspects of domestic water

usage inside Brazilian homes.

• Characterized dwelling composition for high, mid-high, mid-low and low

income households in the Federal District through parameters such as income,

size, tenure, built type, built area, garden/yard area, number of water fixtures and

appliances, presence of swimming pools and their water consumption in

different levels.

• Provided a low-cost and effective water auditing method capable of collecting a

significant sample size of domestic water end-use consumption, regardless of

income and dwelling typology.

With regards to contributions to the field of domestic water conservation, this research

has:

• Identified feasible water conservation measures in terms of their applicability,

water savings and financial benefits for the different income ranges and

residential typologies of the Federal District.

• Offered a better understanding of the water-saving attitudes and public opinion,

awareness and acceptance of water conservation measures for different income

groups.

• Brought together different assessment techniques for the evaluation of water

conservation measures.

• Determined, within the Brazilian context, the applicability of domestic water

conservation measures according to the adaptation of building installations and

public opinion, awareness and acceptance of both demand-side and supply-side

measures.


264

• Identified potential water savings and water reduction indexes for a range of

water conservation measures individually, and in combination.

• Conducted economic assessments of a comprehensive range of demand-side and

supply-side domestic water conservation measures using simple payback period,

life cycle and average incremental cost analysis.

7.5 Limitations of the study

The degree of generalization which can be based on this research is constrained by the

fact that it has been focused in the Federal District. Also, not every single administrative

region of the Federal District has been analysed. Nevertheless, because domestic water

consumption and conservation in different income levels and dwelling typologies were

studied in such depth, some interesting findings which might be relevant to other areas

in Brazil were produced.

The methodologies chosen to undertake this research had their strengths and

weaknesses too. The primary data collection technique used to measure domestic water

end-use consumption through water auditing does not provide the same level of

accuracy as individually metered points of water usage using data-logging equipment,

although data-logging does not work properly when you have water butt, as in Brazil.

Nonetheless, the water auditing method developed, by using diary-tracking techniques

and stop-watches at each point of water usage in the home, fulfilled the requirements of

the research and provided a low-cost method of capable of collecting a larger sample

size of primary data for analysis.

Perhaps the only worry here was that residents were aware that their consumption was

being monitored at all times, affecting the daily habits of water-consuming events.

However, results from the water audits, successfully showed that the accuracy of the

estimated domestic water end-use consumption data collected were within discrepancy

range of metered readings, and findings suggest that they are consistent with previous

findings in published works.

A concluding comment is made about the types of data available for this research. Due

to the lack data regarding the daily frequency of usage for automatically-driven water


265

fixtures, potential reductions for water efficient equipments such as the automatic

faucet, sensor faucet, automatic shut-off hose nozzle and automatic irrigation system

were estimated using percentage-based secondary sources from previous works.

Furthermore, historic time series of hourly or daily rainfall data provide a more precise

estimation of water savings for rainwater harvesting systems. However, such depth of

secondary data is unavailable, so therefore, average monthly rainfall data of a 30 year

time-step for the Federal District was used instead.

7.6 Scope for further research

The study of water consumption and conservation in buildings appears to be now open

to several lines of research. Further studies could benefit from the findings of this

research and amplify its scope, providing further contributions to knowledge and

insights to this current and significant subject.

This study, and as a starting point, this study could be extended to include other cities

and regions in Brazil to expand the number of samples which could allow generalization

over the entire country.

Further research is needed to address the issue of the lack of data regarding the

frequency of daily usage of automatically-driven water fixtures. Adequate data for water

efficient equipments such as the automatic faucet, sensor faucet, automatic shut-off hose

nozzle and automatic irrigation system, can be used to provide more accurate

estimations of water savings. Furthermore, historic time series of hourly or daily rainfall

data could provide a more precise estimation of water savings for rainwater harvesting

systems.

Since cultural values, custom and tradition might be rooted into the way water is used,

further investigations in occupant water-consuming behaviour might provide some

useful insights on how to reduce domestic water consumption through water-saving

attitudes. Other methods for collecting and analysing data on water-consuming activities

could be best addressed through theories of consumer behaviour and behavioural

psychology.


266

7.7 Implications of the findings

Results from this study has made an addition to previous studies by providing specific

information regarding domestic water consumption for different income groups and

dwelling typologies and by identifying feasible domestic water conservation measures

for the Federal District. It seems pertinent to conclude this thesis by relating the

implications of these findings.

Useful water consumption and reduction data from this thesis can be used for the

development of a building certification program destined to promote domestic water

conservation in Brazilian dwellings. Such information could also be applied to the

creation of guidance notes for water conservation in existing and newly built dwellings

in Brazil.

Feasible water-saving strategies have been identified for the different income dwelling

typologies in the Federal District. Findings suggest that low budget water efficient

equipments of simple DIY installation, are capable of promoting water savings and

financial benefits. Water conservation ‘packs’ composed of these simple, low budget

equipments could be distributed to the communities by the local water facility company

as means of reducing water demand to obtain both financial and environmental benefits.

Initial investments made by the company could be paid off through the reduction in

costs related to water production and distribution, water and wastewater treatment, and

wastewater collection.

Findings indicate that although some water conservation measures were capable of

promoting significant reductions on water consumption, overall, they were considered

economically unviable options due to their high costs. Governmental policies and

subsidies over taxes and interest rates could be used as means of promoting incentives

for the general public to invest in water conservation. Tributary tax reductions over

water conservation products could significantly reduce their market price. Furthermore,

low interest rates for long-term investments could also provide means for the general

public to invest on water reuse systems.


267

In sum, results generated from this study could be used as a reference tool for the

development of domestic water conservation programs in the Federal District and in

Brazil.

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Appendices

Appendix A House Survey Questionnaire

Appendix A

282

This survey is part of a PhD study at the Department of Architecture, Oxford Brookes

University, UK, on domestic water conservation in the Federal District, Brazil. The

questionnaire has been designed to analyse social and economic aspects of domestic

water consumption, as well as public awareness and acceptance of water conservation

strategies. You are under no obligation to participate, feel free to withdraw from the

survey at any time without giving a reason, but your kind contribution would be greatly

appreciated. This will only take a short amount of your time, and your answers will be

kept strictly confidential, private and anonymous. If you are unhappy answering any of

the questions, say so and we will move directly to the next question. The information

collected and the data generated shall be retained and safely stored in accordance with

the University’s policy of Academic Integrity. Participants who wish to be provided with

information on the findings and outcomes of the project will be sent a summary report.

This questionnaire has been approved by the University Research Ethics Committee,

but if you have any concerns about the conduct of this survey, please feel free to contact

the Chair of the UREC at Oxford Brookes University ([email protected]).

Please tick (√) or provide your most appropriate response for each question. If you

require any further forms or if you want any further information about the

survey, or would like to ask any questions please contact:

Mr Daniel Sant’Ana

Telephone: +55 (61) 3307-2454

Email: [email protected]

Appendix A

283

1. How many people live in your household?______________

2. Is your home fully owned, being paid off or rented?

□ Owned fully / fully paid off □ Buying / paying off home

□ Renting from private sector □ Renting from public sector

3. In average, what is the household’s total monthly income?

□ Less than R$380 □ R$381 – R$1,900 □ R$1,901 – R$3,800

□ R$3,801 – R$7,600 □ Above R$7,601 □ Don’t know

4. In average, how much do you spend with your monthly water bills?

□ Less than R$25 □ R$25 – R$50 □ R$50 – R$75 □ Above R$75 □ Don’t know

5. a. In your opinion, current pricing of supplied water is:

□ Expensive □ Fair □ Cheap

b. Do you think current prices of mains water encourage water conservation?

□ Yes □ No □ Don’t know

c. Do you feel that dwellings who consume an amount well above average should pay

an additional fee or rate for their water?


d. Do you feel that dwellings who consume an amount well below average should pay a

discounted fee or rate for their water?


6. Please indicate how many of the following water fixtures and appliances you have in

your home.

a. Toilet………………........ □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Bidets………………...… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Shower head………….... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Bathtub…………...…….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Bathroom sink………...... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. Kitchen sink………..…... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

g. Dishwashing machine….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

h. Utility sink water tap…... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

i. Manual clothes washer…. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

j. Clothes washing machine □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

k. External faucet…………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

Appendix A

284

7. Does your dwelling contain low-volume water fixtures or appliances?


8. Does your household contain a swimming pool?

□ Yes □ No

9. Are you aware low-volume water fixtures and appliances are capable of promoting

water savings?

□ Yes □ No

10.a. Are you aware rainwater can be collected, treated and used for irrigation, external

cleansing, vehicle-washing, washing clothes and flushing toilets?

□ Yes □ No

b. Would you use treated rainwater on your household for any such purposes in your

home?

□ Yes □ No

11.a. Are you aware greywater (wash water from showers and sinks) if treated, can be

used for irrigation, vehicle-washing, external cleansing and flushing toilets?

□ Yes □ No

b. Would you use recycled greywater for any such purposes in your home?

□ Yes □ No

12.a. Are you aware that if domestic wastewater is properly treated and disinfected, it can

be used for irrigation, vehicle-washing, external cleansing and flushing toilets?

□ Yes □ No

b. Would you use recycled wastewater for any such purposes in your home?

□ Yes □ No

13. a. Would you be willing to retrofit your home to install water-saving features for both

environmental and financial benefits?

□ Yes □ No

b. Please indicate how much you would be willing to invest per month.

□ I wouldn’t invest □ Below R$100 □ R$101 – R$250 □ R$251 – R$500

□ R$501 – R$750 □ R$751 – R$1,000 □ R$1,001– R$2,000 □ Above R$2001

c. For how long?

□ I wouldn’t invest □ Below 1 month □ 1 – 6 months □ 6 months – 1 year

□ 1 – 2.5 years □ 2.5 – 5 years □ 5 - 10 years □ Above 10 years

Appendix A

285

14.a. In the last years, has your dwelling taken any action to conserve water?


b. If yes, what types of actions have you taken to conserve water?

□ Repaired visible leaks □ Used less water (behavioural

actions)

□ Installed water-saving fittings, fixtures or

appliances

□ Installed water-reuse systems

□ Other (please

specify)_______________________________________________________________

15. How important is it for you to conserve water on a regular basis?

□ Not Important □ Important □ Very important

16. To what degree are you concerned with the future of Brazil’s natural hydrological

resources?

□ Not concerned □ Concerned □ Very concerned

Appendix B Flat Survey Questionnaire

Appendix B

287




















Telephone: +55 (61) 3307-2454


Appendix B

288

1. How many people live in your flat? _______________

2. Is your home fully owned, being paid off or rented?

□ Owned fully / fully paid off □ Buying / paying off home

□ Renting from private sector □ Renting from public sector

3. In average, what is the dwelling’s total monthly income?

□ Less than R$380 □ R$381 – R$1,900 □ R$1,901 – R$3,800

□ R$3,801 – R$7,600 □ Above R$7,601 □ Don’t know

4. In average, how much do you spend with monthly water bills?

□ Less than R$25 □ R$25 – R$50 □ R$50 – R$75 □ Above R$75 □ Don’t know

5. a. In your opinion, current pricing of supplied water is:

□ Expensive □ Fair □ Cheap

b. Do you think current prices of mains water encourage water conservation?


c. Do you feel that buildings who consume an amount well above average should pay

an additional fee or rate for their water?


d. Do you feel that buildings who consume an amount well below average should pay a

discounted fee or rate for their water?


6. Please indicate how many of the following water fixtures and appliances you have in

your home.

a. Toilet….……………… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Bidets………………… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Shower head………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Bathtub……………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Bathroom sink………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. Kitchen sink…………... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


h. Utility sink water tap… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

i. Manual clothes washer….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

j. Clothes washing machine. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

7. Does your flat contain low-volume water fixtures or appliances?


Appendix B

289

8. Are you aware low-volume water fixtures and appliances are capable of promoting

water savings?

□ Yes □ No

9.a. Are you aware rainwater can be collected, treated and used for irrigation, external

cleansing, vehicle-washing, washing clothes and flushing toilets?

□ Yes □ No

b. Would you use treated rainwater for any such purposes in your home?

□ Yes □ No

c. Would you agree to use treated rainwater for any such purposes in your building?

□ Yes □ No

10.a. Are you aware greywater (wastewater from showers and sinks) if treated, can be

used for irrigation, vehicle-washing, external cleansing and flushing toilets?

□ Yes □ No

b. Would you use recycled greywater for any such purposes in your home?

□ Yes □ No

c. Would you agree to use recycled greywater for any such purposes in your building?

□ Yes □ No

11.a. Are you aware that if domestic wastewater is properly treated and disinfected, it can

be used for irrigation, vehicle-washing, external cleansing and flushing toilets?

□ Yes □ No

b. Would you use recycled wastewater for any such purposes in your home?

□ Yes □ No

c. Would you agree to use recycled wastewater for any such purposes in your building?

□ Yes □ No

12. a. Would you be willing to retrofit your flat to install water-saving features for both


□ Yes □ No

b. Please indicate how much you would be willing to invest per month.

□ I wouldn’t invest □ Below R$100 □ R$101 – R$250 □ R$251 – R$500

□ R$501 – R$750 □ R$751 – R$1,000 □ R$1,001– R$2,000 □ Above R$2001

c. For how long?

□ I wouldn’t invest □ Below 1 month □ 1 – 6 months □ 6 months – 1 year


Appendix B

290

13. a. Would you agree to retrofit your building to install water-saving features for both


□ Yes □ No

b. Please indicate how much you would be willing to invest per month (in the shared

bill).

□ I wouldn’t agree □ Below R$100 □ R$101 – R$250 □ R$251 – R$500

□ R$501 – R$750 □ R$751 – R$1,000 □ R$1,001 – R$2,000 □ Above R$2001

c. For how long?

□ I wouldn’t agree □ Below 1 month □ 1 – 6 months □ 6 months – 1 year




b. If yes, what types of actions have you taken to conserve water?

□ Repaired visible leaks □ Used less water (behavioural actions)

□ Installed water-saving fittings, fixtures or

appliances

□ Other (please specify)_____________

15. How important is it for you to conserve water on a regular basis?

□ Not Important □ Important □ Very important

16. To what degree are you concerned with the future of Brazil’s natural hydrological

resources?


Appendix C House Water Audit Questionnaire

Appendix C

292



water audit will be carried out to identify end-use water consumption patterns through

an in-depth interview, taking water measurements and you and your family will be

asked to keep track of your water-use events. This questionnaire is part of the water

audit, and it has been designed to analyse social and economic aspects of domestic




appreciated. Your house has been carefully selected to carry out a water audit amongst

a few others, and due to the small sample size, there might be implications towards your

anonymity. If you are unhappy answering any of the questions, say so and we will move

directly to the next question. The information collected and the data generated shall be

retained and safely stored in accordance with the University’s policy of Academic

Integrity. Participants who wish to be provided with information on the findings and

outcomes of the project will be sent a summary report. This questionnaire has been

approved by the University Research Ethics Committee, but if you have any concerns

about the conduct of this survey, please feel free to contact the Chair of the UREC at

Oxford Brookes University ([email protected]).





Telephone: +55 (61) 3307-2454


Appendix C

293

1. a. Does your home contain a swimming pool?

□ Yes □ No

b. If Yes, how often is it cleaned?___________________________________________

c. How is it cleaned? ______________________________________________________

2. Does the household contain ornamental water features such as fountains?

□ Yes □ No

3. Please indicate how many of the following water efficient fixtures and appliances you

have in your home.

a. Toilet………………….... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Bidets…………………... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Shower head……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Bathtub…………………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Bathroom faucet.……….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. Kitchen tap..…………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


h. Utility sink water tap..…. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


j. Clothes washing machine. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


4. a. Does your dwelling make use of rainwater?

□ Yes □ No

b. If yes, please indicate where rainwater is reused and describe the process.

________________________________________________________________________

________________________________________________________________________

5. a. Does your dwelling make use of greywater?

□ Yes □ No

b. If yes, please indicate where greywater is reused and describe the process.

_______________________________________________________________________

________________________________________________________________________

6. a. Does your dwelling make use of recycled wastewater?

□ Yes □ No

b. If yes, please indicate where greywater is reused and describe the process.

________________________________________________________________________

________________________________________________________________________

Appendix C

294

7. a. On average, how often are dishes washed in your household?

□ < once a week □ 1-2 times a week □ 3-4 times a week □ 5-6 times a week

□ once a day □ 2 times a day □ 3 times a day □ > 3 times a day

b. Usually, how are dishes washed in your household?

□ By hands, with running water at all time □ By hands, controlling the fixture opening

□ By hands – plugged sink □ Dishwasher

□ Other (specify) _________________________________________________________

c. Are the dishes usually rinsed?

□ No, never (dishwasher) □ Yes, only before washing

□ Yes, only after washing □ Yes, before and after washing

□ Other (specify) _________________________________________________________

d. If machine washed, do you use economy settings to your dishwasher?

□ Yes □ No □ Not Applicable

8. a. How are clothes usually washed in your household?

□ Hand washed □ Part is hand washed only, the remaining is machine washed

□ Machine washed □ Part is pre-handwashed before machine washed, the remaining is

machine washed

□ Other (Specify) ________________________________________________________

b. If machine washed, do you use economy settings to your washing machine?


c. On average, how often is a load of clothes washed in your household? ____________

9.a. How many vehicles are used in your house?

□ None □ 1 vehicle □ 2 vehicles □ 3 vehicles □ 4 vehicles □ More than 4 vehicles

b. On average, how often are they washed in your household? ____________________

c. What equipment is normally used?

□ Broom □ Bucket of water and mop

□ Hand-held hose without trigger □ Hand-held hose with trigger

□ Pressurized hose (WAP) □ Other (specify) __________________

10.a. On average, how often are sidewalks, driveways or other external surfaces around

your residence cleaned?

□ Never □ < once a month □ Once a month

□ > once a month □ once a week □ > once a week

Appendix C

295

b. What equipment is normally used?

□ Broom only □ Bucket of water & broom


□ Pressurized hose (WAP) □ Other (please specify) ______________

11.a. During the dry season (April – September), in average, how often do you irrigate

your garden?

□ Never □ < once a month □ once a month □ > once a month

□ once a week □ > once a week □ once a day □ > once a day

b. If you irrigate your garden, which portion is irrigated?

□ The entire garden □ A good portion □ A small portion

c. During the rainy season (October – March), in average, how often do you irrigate

your garden?

□ Never □ < once a month □ once a month □ > once a month

□ once a week □ > once a week □ once a day □ > once a day

d. If you irrigate your garden, which portion is irrigated?

□ The entire garden □ A good portion □ A small portion

e. What equipment is usually used to water your garden?

□ Hand-held garden hose without trigger □ Hand-held garden hose with trigger

□ Soaker hose □ Sub-surface irrigation

□ Sprinklers □ Automatic irrigation system with timer

□ Automatic irrigation system with sensor □ Other (specify)______________________



b. If yes, which actions have you and your family taken to reduce your mains water

consumption?

□ Change in habits of dishwashing □ Change in habits of personal water use

□ Change in habits of floor washing □ Change in habits of clothes washing

□ Change in habits of garden irrigation □ Change in habits of car washing

□ Install water efficient equipment □ Leak repair

□ Install a rainwater reuse system □ Install a greywater reuse system

□ Install a wastewater reuse system □ Other (specify) ____________________

13. Which actions would you and your family take to reduce your water consumption?

□ Nothing □ Change in habits of personal water use

□ Change in habits of dishwashing □ Change in habits of clothes washing

Appendix C

296

□ Change in habits of floor washing □ Change in habits of car washing

□ Change in habits of garden irrigation □ Leak repair

□ Install water efficient equipment □ Install a rainwater reuse system

□ Install a greywater reuse system □ Install a wastewater reuse system

□ Other (specify) ________________________________________________________

Appendix D Flat Water Audit Questionnaire

Appendix D

298



water audit will be carried out to identify end-use water consumption patterns through

an in-depth interview, taking water measurements and you and your family will be

asked to keep track of your water-use events. This questionnaire is part of the water

audit, and it has been designed to analyse social and economic aspects of domestic




appreciated. Your house has been carefully selected to carry out a water audit amongst

a few others, and due to the small sample size, there might be implications towards your

anonymity. If you are unhappy answering any of the questions, say so and we will move

directly to the next question. The information collected and the data generated shall be

retained and safely stored in accordance with the University’s policy of Academic

Integrity. Participants who wish to be provided with information on the findings and

outcomes of the project will be sent a summary report. This questionnaire has been

approved by the University Research Ethics Committee, but if you have any concerns

about the conduct of this survey, please feel free to contact the Chair of the UREC at

Oxford Brookes University ([email protected]).





Telephone: (61) 3307-2454


Appendix D

299

1. a. Does your home contain a swimming pool?

□ Yes □ No

b. If Yes, how often is it cleaned?___________________________________________

c. How is it cleaned? ______________________________________________________

2. Please indicate how many of the following water efficient fixtures and appliances you

have in your home.

a. Toilet………………….... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Bidets…………………... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Shower head……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Bathtub…………………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Bathroom faucet.……….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. Kitchen tap..…………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


h. Utility sink water tap..…. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


j . Clothes washing machine. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more


3. a. On average, how often are dishes washed in your household?

□ < once a week □ 1-2 times a week □ 3-4 times a week □ 5-6 times a week

□ once a day □ 2 times a day □ 3 times a day □ > 3 times a day

b. Usually, how are dishes washed in your household?

□ By hands, with running water at all time □ By hands, controlling the fixture opening

□ By hands – plugged sink □ Dishwasher

□ Other (specify) _________________________________________________________

c. Are the dishes usually rinsed?

□ No, never (dishwasher) □ Yes, only before washing

□ Yes, only after washing □ Yes, before and after washing

□ Other (specify) _________________________________________________________

d. If machine washed, do you use economy settings to your dishwasher?


4. a. How are clothes usually washed in your household?

□ Hand washed □ Part is hand washed only, the remaining is machine washed

□ Machine washed □ Part is pre-handwashed before machine washed, the remaining is

Appendix D

300

machine washed

□ Other (Specify) ________________________________________________________

b. If machine washed, do you use economy settings to your washing machine?


c. On average, how often is a load of clothes washed in your household? ____________



b. If yes, which actions have you and your family taken to reduce your mains water

consumption?

□ Change in habits of dishwashing □ Change in habits of personal water use

□ Change in habits of floor washing □ Change in habits of clothes washing

□ Change in habits of garden irrigation □ Change in habits of car washing

□ Install water efficient equipment □ Leak repair

□ Install a rainwater reuse system □ Install a greywater reuse system

□ Install a wastewater reuse system □ Other (specify) ____________________

6. Which actions would you and your family take to reduce your water consumption?

□ Nothing □ Change in habits of personal water use

□ Change in habits of dishwashing □ Change in habits of clothes washing

□ Change in habits of floor washing □ Change in habits of car washing

□ Change in habits of garden irrigation □ Leak repair

□ Install water efficient equipment □ Install a rainwater reuse system

□ Install a greywater reuse system □ Install a wastewater reuse system

□ Other (specify) ________________________________________________________

Appendix E Residential Building Block Survey

Appendix E

302




















Telephone: +55 (61) 3307-2454


Appendix E

303

1. How many flats per floor are there in the building? ____________________________

2. In average, how much water does the building consume in a monthly basis?

Water meter 1:_________________m3 Water meter 2 (If existant):____________m3

3. In average, how much does the building spend with monthly water bills? R$________

4. In average, how much is the monthly condominium bill? R$____________________

5. a. Is the building sub-metered?

□ Yes □ No

6. How many of the following water fixtures and appliances are available on the

building’s communal grounds?

a. Toilet……………............ □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Shower head……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Bathroom sink………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Kitchen sink……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Utility sink……………… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. External faucet………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

7. Does the building contain a communal swimming pool?

□ Yes □ No

8. Please indicate if the building presents leakage on any of the following places, and

quantify them.

a. Toilet………………….... □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

b. Shower head……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

c. Bathroom sink………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

d. Kitchen sink……………. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

e. Utility sink……………… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

f. External faucet………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

g. Swimming pool………… □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

h. Pipework……………….. □ 0 □ 1 □ 2 □ 3 □ 4 □ 5 □ 6 □ 7 or more

9.a. On average, how often are sidewalks, communal areas, driveways or other external

surfaces around the building cleaned?

□ Never □ Less than once a month □ Once a month

□ More than once a month □ Once a week □ More than once a week

Appendix E

304

b. What equipment is normally used?

□ Broom only □ Bucket of water & broom


□ Pressurized hose (WAP) □ Other (please specify) _____________

10.a. During the dry season (April – September), in average, how often are the gardens

irrigated?

□ No garden □ Never □ Less than once a month □ Once a month

□ > a once a month □ Once a week □ More than once a week □ Once a day

b. During the rainy season (October – March), in average, how often are the gardens

irrigated?

□ No garden □ Never □ Less than once a month □ Once a month

□ > once a month □ Once a week □ More than once a week □ Once a day

c. What equipment is used to water the gardens?

□ No garden □ Hand-held garden hose without trigger

□ Hand-held garden hose with trigger □ Soaker hose

□ Sprinklers □ Underground irrigation system

□ Automatic irrigation system (timer) □ Automatic irrigation system (sensor)

□ Other (please specify) _______________________________________________________

11.a. In the last years, has the building taken any action to conserve water?

□ Yes □ No

b. If yes, what types of actions has the building taken to conserve water?

□ Repaired leaks □ Installed water-saving fittings, fixtures or appliances

□ Installed water-reuse systems □ Other (please specify) ____________________________

12. To what degree is the building concerned with saving water?


Appendix F Diary-Tracking Cards

Appendix F

306

Diary-Tracking Card for Toilet Flushing

Day No. of Flushes

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Please indicate the number of times the toilet has been flushed per day.

Example: = 7 = 7 IIIIIII = 7 XXXXXXX = 7

Diary-Tracking Card for Washing Machine and Dishwashers

Load Day Type of Program Selected

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

For each washing load, please indicate the day and type of program selected.

Appendix G Diary-Tracking Summary Card

Appendix G

308

Example of Diary-Tracking Summary Card

DAILY READINGS FROM STOP-WATCHES

Address

Water Fixture Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7

Bathroom 1

Lavatory Faucet

Shower Head

Bidet / Hand Douche

Toilet Flush

Bathroom 2

Lavatory Faucet

Shower Head

Bidet / Hand Douche

Toilet Flush

Kitchen

Kitchen Faucet

Water Filter

Laundry / Utility Room

Utility Sink Faucet

Washing Machine

Garden / Yard

External Tap

Appendix H Water Audit Inventory Form

Appendix H

310

Background Information Dwelling Address: Owner: No. of Residents: Building Type: Built Area: Garden / Yard Area: Roof Area: No. of Bathrooms: Swimming Pool Volume: Meter Reading Before Audit: Meter Reading After Audit: Start Date: End Date:

General Consumption Is the dwelling mains connected? � Yes � Partially � No If Partially, Specify water source(s): _________________________________________________, and points used ________________________________________________________ If No, Specify water source:____________________________________________________ Metered Readings Is the dwelling individually metered? � Yes � No If Yes, is a copy of the water bill available? � Yes � No Notes _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Drawings

Appendix H

311

Bathrooms Toilets

No. ID. Model/Type Type of Flush

Flush Vol. Leak?

1. 2. 3. 4. 5. Bidets / Hand Douches

Sink Faucets

No. ID. Model/Type Aerator? Flow Vol. Leak?

1. 2. 3. 4. 5. Bath Faucets

No. ID. Model/Type Flow Vol. Leak?

1. 2. 3. 4. 5. 6. Shower Head No. ID. Model/Type Flow Vol. Leak? 1. 2. 3. 4. 5.

No. ID. Model/Type Flow Vol. Leak? 1. 2. 3. 4. 5.

Appendix H

312

Kitchen Kitchen sink

No. Model/Type Aerator? Flow Vol. Leak?

1. 2. 3. 4. 5. Dishwasher

No. Model/Type Load Capacity

Design Vol. Leak?

1. 2. Utility Area Washing Machine

No. Model/Type Load Capacity

Design Vol. Leak?

1. 2. Utility Sink Faucet

No. Model/Type Flow Vol. Leak?

1. 2. External Area External Taps / Other

No. Model/Type Flow Vol. Leak?

1. 2. 3. 4. 5.

Appendix I Capital Costs of Automatic Irrigation System

Appendix I

314

Capital Costs of Automatic Irrigation System

Code Description Un. Quant. Unit Price Total

1. AUTOMATIC IRRIGATION SPRINKLER SYSTEM R$ 1,145.81

1.1. Adjustable range pop-up sprinkler 5 R$ 18.33 R$ 91.66

1.2. System connector set 2 R$ 42.37 R$ 84.74

1.3. Water computer for automated irrigation 1 R$ 262.97 R$ 262.97

1.4. L-piece male thread for sprinkler connection DN25 5 R$ 8.71 R$ 43.53

1.5. T-piece - female thread DN25 2 R$ 13.41 R$ 26.83

1.6. T-piece for pipe branching DN25 3 R$ 14.07 R$ 42.21

1.7. Female thread connector DN25 2 R$ 7.13 R$ 14.25

1.8. Connector DN25 2 R$ 9.39 R$ 18.78

1.9. Drain valve DN25 2 R$ 24.59 R$ 49.18

1.10. 50m Connecting pipe DN25 1 R$ 167.85 R$ 167.85

1.11. Irrigation control system 1 R$ 223.81 R$ 223.81

1.12. Installation cost R$ 120.00

Appendix J Performance of Rainwater Harvesting Systems

for High Income Dwellings

Appendix J

316

BASELINE END-USE WATER CONSUMPTION SCENARIO: REUSE 1

A = 111m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)

Rainwater Storage Volume

1 m3 5 m3 10 m3 15 m3 20 m3 25 m3 30 m3 35 m3

Jan 269 24 7 1.0 5 10 15 17 17 17 17 Feb 214 19 7 1.0 5 10 15 20 25 29 29 Mar 185 17 7 1.0 5 10 15 20 25 30 35 Apr 111 10 7 1.0 5 10 15 20 25 30 35 May 31 3 7 -3.3 1 6 11 16 21 26 31 Jun 5 0 7 -6.6 -6 -1 4 9 14 19 24 Jul 7 1 7 -6.5 -6 -6 -2 3 8 13 18 Aug 10 1 7 -6.2 -6 -6 -6 -4 1 6 11 Sep 38 3 7 -3.7 -4 -4 -4 -4 -2 3 8 Oct 148 13 7 1.0 5 6 6 6 6 9 14 Nov 197 18 7 1.0 5 10 15 17 17 20 25 Dec 287 26 7 1.0 5 10 15 20 25 30 35

Water Savings (m3/yr) 59 63 68 73 78 83 85 85

Appendix J

317


A = 176m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3 20 m3 25 m3 30 m3 35 m3 40m3 45 m3

Jan 269 38 12 1 5 10 15 20 25 26 26 26 38 Feb 214 31 12 1 5 10 15 20 25 30 35 40 45 Mar 185 26 12 1 5 10 15 20 25 30 35 40 45 Apr 111 16 12 1 5 10 15 20 25 30 35 40 45 May 31 4 12 -7 -3 2 7 12 17 22 27 32 42 Jun 5 1 12 -11 -11 -9 -4 1 6 11 16 21 36 Jul 7 1 12 -11 -11 -11 -11 -10 -5 -0.3 5 10 30 Aug 10 1 12 -11 -11 -11 -11 -11 -11 -11 -6 -1 24 Sep 38 5 12 -7 -7 -7 -7 -7 -7 -7 -7 -7 23 Oct 148 21 12 1 5 9 9 9 9 9 9 9 37 Nov 197 28 12 1 5 10 15 20 25 25 25 25 45 Dec 287 41 12 1 5 10 15 20 25 30 35 40 45

Water Savings (m3/yr)

99 103 108 113 118 123 128 133 138 146

Appendix J

318


A = 264m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


10 m3 20 m3 30m3 40 m3 50 m3 60 m3 70 m3 80 m3

Jan 269 58 19 10 20 30 38 38 38 38 38

Feb 214 46 19 10 20 30 40 50 60 65 65

Mar 185 40 19 10 20 30 40 50 60 70 80

Apr 111 24 19 10 20 30 40 50 60 70 80

May 31 7 19 -2 8 18 28 38 48 58 68

Jun 5 1 19 -18 -10 -0.4 10 20 30 40 50

Jul 7 1 19 -18 -18 -18 -8 2 12 22 32

Aug 10 2 19 -17 -17 -17 -17 -15 -5 5 15

Sep 38 8 19 -11 -11 -11 -11 -11 -11 -6 4

Oct 148 32 19 10 13 13 13 13 13 13 17

Nov 197 42 19 10 20 30 36 36 36 36 40

Dec 287 61 19 10 20 30 40 50 60 70 80


Appendix J

319

REDUCED END-USE WATER CONSUMPTION SCENARIO: REUSE 1

A = 26m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3

Jan 269 6 2 1 4 4 Feb 214 5 2 1 5 7 Mar 185 4 2 1 5 9 Apr 111 2 2 1 5 10 May 31 1 2 0 4 9 Jun 5 0 2 -2 2 7 Jul 7 0 2 -2 1 6 Aug 10 0 2 -1 -1 4 Sep 38 1 2 -1 -1 3 Oct 148 3 2 1 1 5 Nov 197 4 2 1 4 7 Dec 287 6 2 1 5 10

Water Savings (m3/yr) 15 19 20


A = 52m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3

Jan 269 11 4 1 5 8 8 Feb 214 9 4 1 5 10 13 Mar 185 8 4 1 5 10 15 Apr 111 5 4 1 5 10 15 May 31 1 4 -1 3 8 13 Jun 5 0 4 -3 -1 4 9 Jul 7 0 4 -3 -3 1 6 Aug 10 0 4 -3 -3 -3 2 Sep 38 2 4 -2 -2 -2 0 Oct 148 6 4 1 3 3 3 Nov 197 8 4 1 5 7 7 Dec 287 12 4 1 5 10 15

Water Savings (m3/yr) 31 35 40 44

Appendix J

320


A = 110m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3 20 m3 25 m3 30m3 35 m3

Jan 269 24 8 1 5 10 15 16 16 16 16 Feb 214 19 8 1 5 10 15 20 25 27 27 Mar 185 16 8 1 5 10 15 20 25 30 35 Apr 111 10 8 1 5 10 15 20 25 30 35 May 31 3 8 -4 -0.5 5 10 15 20 25 30 Jun 5 0 8 -8 -8 -3 2 7 12 17 22 Jul 7 1 8 -8 -8 -8 -6 -1 4 9 14 Aug 10 1 8 -7 -7 -7 -7 -7 -3 2 7 Sep 38 3 8 -5 -5 -5 -5 -5 -5 -3 2 Oct 148 13 8 1 5 5 5 5 5 5 7 Nov 197 18 8 1 5 10 14 14 14 14 16 Dec 287 26 8 1 5 10 15 20 25 30 34


Appendix K Performance of Rainwater Harvesting Systems

for Mid-High Income Dwellings

Appendix K

322


A = 200m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 10 m3 20 m3 30 m3 40 m3 50 m3 60 m3 70 m3

Jan 269 44 16 1 10 20 28 28 28 28 28

Feb 214 35 16 1 10 20 30 40 47 47 47

Mar 185 30 16 1 10 20 30 40 50 60 61

Apr 111 18 16 1 10 20 30 40 50 60 63

May 31 5 16 -11 -1 9 19 29 39 49 53

Jun 5 1 16 -15 -15 -6 4 14 24 34 38

Jul 7 1 16 -15 -15 -15 -10 0 10 20 23

Aug 10 2 16 -14 -14 -14 -14 -14 -4 6 9

Sep 38 6 16 -10 -10 -10 -10 -10 -10 -4 0

Oct 148 24 16 1 8 8 8 8 8 8 8

Nov 197 32 16 1 10 20 24 24 24 24 24

Dec 287 46 16 1 10 20 30 40 50 50 55


Appendix K

323


Unfeasible, because demand greatly exceeds supply due to the lack of roof area.

If, � = k × l × V × F

Q = Annual Rainwater Demand (litres) R = Average Annual Rainfall (mm) A = Roof Area (m2) Cr = Runoff Coefficient Cf = Filter Coefficient

Then, lpqx = �k� × V × F


Hence,

Amin = 2,890,000

1,502 × 0.9 × 0.9 = 2,376m2

Available Roof Area = 1,095m2

0

500

1000

1500

2000

2500

3000

3500


Cumulative Rainwater Supply Cumulative Rainwater Demand

Appendix K

324



If, � = k × l × V × F




Hence,

Amin = 8,365,000

1,502 × 0.9 × 0.9 = 6,876m2


0

1000

2000

3000

4000

5000

6000

7000

8000

9000


Cummulative Rainwater Supply Cummulative Rainwater Demand

Appendix K

325


A = 47m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3

Jan 269 10 4 1 5 7 7 Feb 214 8 4 1 5 10 11 Mar 185 7 4 1 5 10 14 Apr 111 4 4 1 5 10 15 May 31 1 4 -2 2 7 12 Jun 5 0 4 -4 -1 4 9 Jul 7 0 4 -3 -3 1 5 Aug 10 0 4 -3 -3 -3 2 Sep 38 1 4 -2 -2 -2 0 Oct 148 6 4 1 2 2 2 Nov 197 7 4 1 5 6 6 Dec 287 11 4 1 5 10 13



A = 1,095m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


20 m3 40 m3 60 m3 80 m3 100m3

Jan 269 239 98 20 40 60 80 100 Feb 214 190 98 20 40 60 80 100 Mar 185 164 98 20 40 60 80 100 Apr 111 98 98 20 40 60 80 100 May 31 27 98 -51 -31 -11 9 29 Jun 5 4 98 -94 -94 -94 -85 -65 Jul 7 6 98 -92 -92 -92 -92 -92 Aug 10 9 98 -89 -89 -89 -89 -89 Sep 38 34 98 -65 -65 -65 -65 -65 Oct 148 131 98 20 33 33 33 33 Nov 197 175 98 20 40 60 76 76 Dec 287 255 98 20 40 60 80 100

Water Savings (m3/yr) 788 808 828 848 868

Appendix K

326



If, � = k × l × V × F




Hence,

Amin = 4,278,000

1,502 × 0.9 × 0.9 = 3,523m2


0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000


Cummulative Rainwater Supply Cummulative Rainwater Demand

Appendix L Performance of Rainwater Harvesting Systems

for Mid-Low Income Dwellings

Appendix L

328


A = 21m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3

Jan 269 5 2 1 3 3 Feb 214 4 2 1 5 5 Mar 185 3 2 1 5 7 Apr 111 2 2 1 5 7 May 31 1 2 0 4 6 Jun 5 0 2 -2 2 4 Jul 7 0 2 -1 1 3 Aug 10 0 2 -1 0 1 Sep 38 1 2 -1 -1 1 Oct 148 3 2 1 1 1 Nov 197 3 2 1 3 3 Dec 287 5 2 1 5 7


Appendix L

329


A = 71m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3 20 m3 25 m3

Jan 269 15 6 1 5 10 10 10 10

Feb 214 12 6 1 5 10 15 17 17

Mar 185 11 6 1 5 10 15 20 22

Apr 111 6 6 1 5 10 15 20 23

May 31 2 6 -3 1 6 11 16 19

Jun 5 0 6 -5 -4 1 6 11 13

Jul 7 0 6 -5 -5 -4 1 6 8

Aug 10 1 6 -5 -5 -5 -4 1 3

Sep 38 2 6 -3 -3 -3 -3 -3 0

Oct 148 9 6 1 3 3 3 0 3

Nov 197 11 6 1 5 9 9 6 9

Dec 287 17 6 1 5 10 15 17 20

Water Savings (m3/yr) 45 49 54 59 64 67

Appendix L

330


A = 130m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


5 m3 10 m3 15 m3 20 m3 25 m3 30m3 35 m3 40 m3

Jan 269 28 11 5 10 15 17 17 17 17 17

Feb 214 23 11 5 10 15 20 25 28 28 28

Mar 185 19 11 5 10 15 20 25 30 35 36

Apr 111 12 11 5 10 15 20 25 30 35 37

May 31 0 11 -6 -1 4 9 14 19 24 25

Jun 5 1 11 -11 -11 -7 -2 3 8 13 15

Jul 7 1 11 -11 -11 -11 -11 -8 -3 2 4

Aug 10 1 11 -10 -10 -10 -10 -10 -10 -8 -6

Sep 38 4 11 -7 -7 -7 -7 -7 -7 -7 -7

Oct 148 16 11 4 4 4 4 4 4 4 4

Nov 197 21 11 5 10 14 14 14 14 14 14

Dec 287 30 11 5 10 15 20 25 30 33 33


Appendix L

331


A = 13m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)

Rainwater Storage

1 m3 5 m3

Jan 269 3 1 1 2 Feb 214 2 1 1 3 Mar 185 2 1 1 4 Apr 111 1 1 1 4 May 31 0 1 0 4 Jun 5 0 1 -1 3 Jul 7 0 1 -1 2 Aug 10 0 1 -1 1 Sep 38 0 1 -1 0 Oct 148 2 1 1 1 Nov 197 2 1 1 2 Dec 287 3 1 1 4

Water Savings (m3/yr) 9 12


A = 35m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3

Jan 269 8 3 1 5 5 5 Feb 214 6 3 1 5 8 8 Mar 185 5 3 1 5 10 11 Apr 111 3 3 1 5 10 11 May 31 1 3 -1 3 8 9 Jun 5 0 3 -3 1 6 7 Jul 7 0 3 -3 -2 3 4 Aug 10 0 3 -2 -2 1 2 Sep 38 1 3 -2 -2 -1 0 Oct 148 4 3 1 1 1 2 Nov 197 6 3 1 4 4 4 Dec 287 8 3 1 5 10 10


Appendix L

332


A = 83m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3 20 m3 25 m3 30m3

Jan 269 18 6 1 5 10 12 12 12 12 Feb 214 14 6 1 5 10 15 19 19 19 Mar 185 12 6 1 5 10 15 20 25 25 Apr 111 7 6 1 5 10 15 20 25 26 May 31 2 6 -3 1 6 11 16 21 22 Jun 5 0 6 -6 -6 -1 4 9 14 16 Jul 7 0 6 -6 -6 -6 -2 3 8 10 Aug 10 1 6 -6 -6 -6 -6 -2 3 4 Sep 38 3 6 -4 -4 -4 -4 -4 -1 0 Oct 148 10 6 1 3 3 3 3 3 4 Nov 197 13 6 1 5 10 10 10 10 10 Dec 287 19 6 1 5 10 15 20 23 23

Water Savings (m3/yr) 53 57 62 67 72 77 78

Appendix M Performance of Rainwater Harvesting Systems

for Low Income Dwellings

Appendix M

334


A = 17m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)

Rainwater Storage

1 m3 5 m3

Jan 269 4 1 1 2 Feb 214 3 1 1 4 Mar 185 3 1 1 5 Apr 111 2 1 1 5 May 31 0 1 0 4 Jun 5 0 1 -1 3 Jul 7 0 1 -1 2 Aug 10 0 1 -1 1 Sep 38 1 1 -1 0 Oct 148 2 1 1 1 Nov 197 3 1 1 2 Dec 287 4 1 1 5



A = 52m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


5 m3 10 m3 15 m3 20 m3

Jan 269 11 4 5 7 7 7 Feb 214 9 4 5 10 12 12 Mar 185 8 4 5 10 15 16 Apr 111 5 4 5 10 15 16 May 31 1 4 2 7 12 13 Jun 5 0 4 -2 3 8 10 Jul 7 0 4 -4 -1 4 6 Aug 10 0 4 -4 -4 1 2 Sep 38 2 4 -3 -3 -2 0 Oct 148 6 4 2 2 2 2 Nov 197 8 4 5 6 6 6 Dec 287 12 4 5 10 14 14


Appendix M

335


A = 97m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


5 m3 10 m3 15 m3 20 m3 25 m3 30m3

Jan 269 21 8 5 10 13 13 13 13 Feb 214 17 8 5 10 15 20 21 21 Mar 185 15 8 5 10 15 20 25 28 Apr 111 9 8 5 10 15 20 25 28 May 31 2 8 -1 4 9 14 19 22 Jun 5 0 8 -8 -4 1 6 11 14 Jul 7 1 8 -8 -8 -6 -1 4 7 Aug 10 1 8 -8 -8 -8 -8 -4 -1 Sep 38 3 8 -5 -5 -5 -5 -5 -6 Oct 148 12 8 3 3 3 3 3 3 Nov 197 15 8 5 10 11 11 11 11 Dec 287 23 8 5 10 15 20 25 25

Water Savings (m3/yr) 70 75 80 85 90 93

Appendix M

336


A = 12m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)

Rainwater Storage

1 m3 5 m3

Jan 269 3 1 1 2 Feb 214 2 1 1 3 Mar 185 2 1 1 4 Apr 111 1 1 1 4 May 31 0 1 0 4 Jun 5 0 1 0 3 Jul 7 0 1 -1 2 Aug 10 0 1 -1 1 Sep 38 0 1 -1 1 Oct 148 1 1 1 1 Nov 197 2 1 1 2 Dec 287 3 1 1 4



A = 28m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3

Jan 269 6 2 1 4 4 Feb 214 5 2 1 5 7 Mar 185 4 2 1 5 8 Apr 111 3 2 1 5 9 May 31 1 2 -1 3 7 Jun 5 0 2 -2 1 5 Jul 7 0 2 -2 -1 3 Aug 10 0 2 -2 -2 1 Sep 38 1 2 -1 -1 0 Oct 148 3 2 1 1 1 Nov 197 4 2 1 3 3 Dec 287 7 2 1 5 8


Appendix M

337


A = 97m2, Cr = 0.9, Cf = 0.9

Month R (mm/month)

S (m

3/month)

Q (m

3/month)


1 m3 5 m3 10 m3 15 m3 20 m3

Jan 269 14 5 1 5 9 9 9 Feb 214 11 5 1 5 10 15 15 Mar 185 9 5 1 5 10 15 19 Apr 111 6 5 1 5 10 15 20 May 31 2 5 -2 2 7 12 16 Jun 5 0 5 -5 -3 2 7 12 Jul 7 0 5 -5 -5 -3 2 7 Aug 10 1 5 -4 -4 -4 -2 3 Sep 38 2 5 -3 -3 -3 -3 0 Oct 148 8 5 1 3 3 3 3 Nov 197 10 5 1 5 8 8 8 Dec 287 15 5 1 5 10 15 17

Water Savings (m3/yr) 41 45 50 55 59

Appendix N Cost of Rainwater Harvesting Systems

Appendix N

339

RAINWATER CISTERNS

Code Description Measure Quant. Unit Price Total

1. 1m3 RAINWATER CISTERN R$ 411.15

1.1. 1m3 polyethelyne rainwater butt r=1.40 h=0.85 1 R$ 342.90 R$ 342.90

1.2. Polyethylene inlet hose DN32 1 R$ 15.70 R$ 15.70

1.3. PVC conector for rainwater butt DN32 1 R$ 12.55 R$ 12.55


2. 5m

3 RAINWATER CISTERN R$ 3,997.50

2.1. 5m3 polyethelyne rainwater cistern r=2.24 h=1.83 1 R$ 3,327.00 R$ 3,327.00

2.2. Calmed smoothing inlet DN100 1 R$ 31.80 R$ 31.80

2.3. 3m PVC calmed inlet pipe DN100 1 R$ 17.20 R$ 17.20

2.4. 90o PVC long curve elbow connection DN100 1 R$ 29.80 R$ 29.80

2.5. Overflow siphon with backflow prevention valve DN100 1 R$ 47.70 R$ 47.70

2.6. Backflow and vermin retention valve DN100 1 R$ 30.00 R$ 30.00

2.7. Floating suction filter with flexible hose and connection DN25 1 R$ 514.00 R$ 514.00

2.8. Site preparation and installation cost R$ 320.00

3. 10m










3. 15m










4. 20m



4.2. Tank connection set DN100 1 R$ 24.80 R$ 24.80








5. 25m












Continues on the next page.

Appendix N

340


6. 30m3 RAINWATER CISTERN R$ 13,651.30









6.9. Site preparation and installation cost R$ 1,120.00

































Continues on the next page.

Appendix N

341



10.1. 50m3 concrete rainwater cistern 5.00x3.33x3.00 1 R$ 25,000.00 R$ 25,000.00








11. 60m










12. 70m










13. 80m










14. 90m










15. 100m










Appendix N

342

HIGH INCOME DWELLINGS

Baseline water end-use consumption scenario – Reuse 1


1. RAINWATER COLLECTION PIPEWORK R$ 1,165.50

1.1. 3m PVC gutter 132x89 4 R$ 51.25 R$ 205.00

1.2. Gutter union bracket 132x89 3 R$ 14.10 R$ 42.30

1.3. Gutter support bracket 132x89 20 R$ 4.70 R$ 94.00

1.4. Gutter running outlet 132x89 1 R$ 26.90 R$ 26.90

1.5. External stop end 132x89 2 R$ 7.15 R$ 14.30

1.7. 60o PVC offset bends DN80 2 R$ 10.90 R$ 21.80

1.8. 3m PVC Downpipe DN80 1 R$ 46.00 R$ 46.00

1.9. Downpipe bracket DN80 2 R$ 5.20 R$ 10.40

1.10. PVC "T" connection with inspection acess DN80 1 R$ 11.95 R$ 11.95

1.11. 90o PVC downpipe transition elbow connection 80x100 1 R$ 23.25 R$ 23.25

1.12. 3m PVC collection pipe DN100 3 R$ 17.20 R$ 51.60

1.13. Rainwater filter DN100 1 R$ 498.00 R$ 498.00


2. RAINWATER DRAINAGE PIPEWORK R$ 88.45

2.1. 3m PVC drainage pipe DN100 2 R$ 17.20 R$ 34.40

2.2. 45o PVC elbow connection DN100 1 R$ 5.85 R$ 5.85

2.3. PVC "T"connection DN100 1 R$ 8.20 R$ 8.20


3. TREATED RAINWATER DISTRIBUTION PIPEWORK R$ 270.20

3.1. PVC connector with free flanges for rainwater cistern DN25 1 R$ 7.70 R$ 7.70

3.2. 3m PVC suction pipe DN25 1 R$ 4.85 R$ 4.85

3.3. 90o PVC elbow conection DN25 1 R$ 0.35 R$ 0.35

3.4. Garden water pump 1/4hp DN25 1 R$ 200.00 R$ 200.00

3.5. Hose bib garden tap kit DN25 1 R$ 17.30 R$ 17.30


TOTAL COST R$ 1,524.15


1. OPERATIONAL COSTS R$ 14.18

1.1. Garden water pump 1/4hp 450 W 105 hr/yr R$ 0,30 kwh R$ 14.18

TOTAL COST R$ 14.18

Appendix N

343





1.1. 3m PVC gutter 132x89 12 R$ 51.25 R$ 597.92


















3. TREATED RAINWATER DISTRIBUTION PIPEWORK R$ 2,344.75

3.1. PVC connector with ring for rainwater cistern DN25 1 R$ 7.70 R$ 7.70





3.6. Distribution water pump 1/4hp DN25 1 R$ 200.00 R$ 200.00

3.8. 500 litres rainwater loft tank 1 R$ 144.60 R$ 144.60

3.9. Distribution water pump float switch 1 R$ 29.75 R$ 29.75

3.9. Potable water feed backup set 1 R$ 1,300.00 R$ 1,300.00

3.10. PVC connector with free flanges for rainwater loft tank DN25 1 R$ 7.70 R$ 7.70



3.13. PVC "T" connection DN32 1 R$ 2.00 R$ 2.00


3.15. 3m PVC overflow pipe DN32 1 R$ 15.70 R$ 15.70

3.16. PVC ball valve DN32 1 R$ 39.00 R$ 39.00

3.17. 3m PVC distribution pipe DN40 10 R$ 8.70 R$ 87.00






1.2. Distribution water pump 1/4hp 450 W 62 hr/yr R$ 0,30 kwh R$ 8.37

TOTAL COST R$ 22.55

Appendix N

344





1.1. 3m PVC gutter 132x89 15 R$ 51.25 R$ 768.75












1.14. PVC branch connection DN100 1 R$ 14.20 R$ 14.20



























3.19 Installation cost R$ 240.00






TOTAL COST R$ 38.75

Appendix N

345


Reduced water end-use consumption scenario – Reuse 1


1. RAINWATER COLLECTION PIPEWORK R$ 930.60

1.1. 3m PVC gutter 132x89 2 R$ 51.25 R$ 102.50





























TOTAL COST R$ 14.18

Appendix N

346





1.1. 3m PVC gutter 132x89 4 R$ 51.25 R$ 205.00










































TOTAL COST R$ 22.55

Appendix N

347





1.1. 3m PVC gutter 132x89 5 R$ 51.25 R$ 256.25











































TOTAL COST R$ 38.75

Appendix N

348

MID-HIGH INCOME DWELLINGS

Baseline and reduced water end-use consumption scenarios – Reuse 1



1.1. Rainwater diversion chamber DN100/300 1 R$ 78.35 R$ 78.35


1.3. Rainwater filter DN100 1 R$ 1,394.00 R$ 1,394.00


















TOTAL COST R$ 25.65

Appendix N

349





1.12. 6m PVC collection pipe DN150 20 R$ 111.55 R$ 2,231.00





2.2. 45o PVC elbow connection 2 R$ 5.85 R$ 11.70

2.3. Inspection Chamber DN100/300 1 R$ 78.35 R$ 78.35








3.5. Distribution water pump 1hp DN25 1 R$ 400.00 R$ 400.00

3.6. 2,500 litres rainwater loft tank 2 R$ 990.40 R$ 1,980.80


















1.2. Distribution water pump 1hp 1300W 2731 hr/yr R$ 0,30 kwh R$ 368.69

TOTAL COST R$ 394.34

Appendix N

350





1.12. 6m PVC collection pipe DN150 20 R$ 111.55 R$ 2,231.00





2.2. 45o PVC elbow connection 2 R$ 5.85 R$ 11.70

2.3. Inspection Chamber DN100/300 1 R$ 78.35 R$ 78.35









3.6. 2,500 litres rainwater loft tank 2 R$ 990.40 R$ 1,980.80






















Appendix N

351

MID-LOW INCOME DWELLINGS




1.1. 3m PVC gutter 132x89 2 R$ 51.25 R$ 102.50




























1.1. Garden water pump 1/4hp 450 W 34,7 hr/yr R$ 0,30 kwh R$ 4.68

TOTAL COST R$ 4.68

Appendix N

352





1.1. 3m PVC gutter 132x89 3 R$ 51.25 R$ 136.67









































1.2. Distribution water pump 1/4hp 450 W 43,7hr/yr R$ 0,30 kwh R$ 5.90

TOTAL COST R$ 10.58

Appendix N

353





1.1. 3m PVC gutter 132x89 3 R$ 51.25 R$ 170.83











































TOTAL COST R$ 19.09

Appendix N

354





1.1. 3m PVC gutter 132x89 2 R$ 51.25 R$ 102.50





























TOTAL COST R$ 4.68

Appendix N

355





1.1. 3m PVC gutter 132x89 2 R$ 51.25 R$ 102.50










































TOTAL COST R$ 10.58

Appendix N

356





1.1. 3m PVC gutter 132x89 3 R$ 51.25 R$ 170.83











































TOTAL COST R$ 19.09

Appendix N

357

LOW INCOME DWELLINGS




1.1. 3m PVC gutter 132x89 1 R$ 51.25 R$ 51.25




























1.1. Garden water pump 1/4hp 450 W 35,4hr/yr R$ 0,30 kwh R$ 4.78

TOTAL COST R$ 4.78

Appendix N

358





1.1. 3m PVC gutter 132x89 3 R$ 51.25 R$ 136.67









































1.2. Distribution water pump 1/4hp 450 W 31hr/yr R$ 0,30 kwh R$ 4.19

TOTAL COST R$ 8.96

Appendix N

359





1.1. 3m PVC gutter 132x89 6 R$ 51.25 R$ 307.50











































TOTAL COST R$ 13.42

Appendix N

360





1.1. 3m PVC gutter 132x89 1 R$ 51.25 R$ 51.25





























TOTAL COST R$ 4.78

Appendix N

361





1.1. 3m PVC gutter 132x89 2 R$ 51.25 R$ 102.50










































TOTAL COST R$ 8.96

Appendix N

362





1.1. 3m PVC gutter 132x89 3 R$ 51.25 R$ 170.83











































TOTAL COST R$ 13.42

Appendix O Costs of Greywater Recycling Systems

Appendix O

364


Greywater diversion for subsurface irrigation


1. GREYWATER COLLECTION PIPEWORK R$ 1,212.20


1.2. Inspection chamber DN50/100 7 R$ 125.35 R$ 877.45



2. GREYWATER DRAINAGE PIPEWORK R$ 960.05


2.2. Inspection chamber DN100 7 R$ 125.35 R$ 877.45



3. GREYWATER DIVERSION DEVICE R$ 3,115.88

3.1. 300 litres greywater surge tank 1 R$ 94.70


3.3. 3m PVC perforated irrigation pipe DN25 100 R$ 4.85 R$ 485.00


3.4. PVC "T" conection DN25 60 R$ 0.80 R$ 48.00

3.2. Geotextile membrane m2 150 R$ 0.54 R$ 81.00

3.2. 20mm aggregate m3 13.5 R$ 63.48 R$ 856.98

3.2. Sand m3 13.5 R$ 83.30 R$ 1,124.55



Appendix O

365


Greywater treatment system – Reuse 1












3. GREYWATER TREATMENT SYSTEM R$ 3,035.00

3.1. Greywater treatment station R$ 2,795.00


4. TREATED GREYWATER DISTRIBUTION PIPEWORK R$ 270.20

4.1. PVC connector with free flanges for greywater tank DN25 1 R$ 7.70 R$ 7.70










1.2. Greywater treatment system 300 W 4380 hr/yr R$ 0,30 kwh R$ 394.20

1.3. Maintenance R$ 50.00


Appendix O

366

















4. TREATED GREYWATER DISTRIBUTION PIPEWORK R$ 2,345.55











4.10. PVC connector with free flanges for greywater loft tank DN25 1 R$ 7.70 R$ 7.70















1.4. System maintenance R$ 100.00


Appendix O

367













































Appendix O

368




1. GREYWATER COLLECTION PIPEWORK R$ 508.55

























Appendix O

369





















4.6. 2,500 litres greywater loft tank 2 R$ 990.40 R$ 1,980.80
















1. OPERATIONAL COSTS R$ 1,432.74






Appendix O

370





1.2. Inspection chamber DN50/10

0 4 R$ 125.35 R$ 501.40
















4.6. 2,500 litres greywater loft tank 2 R$ 990.40 R$ 1,980.80

























Appendix O

371






























Appendix O

372












































Appendix O

373












































Appendix O

374





























Appendix O

375













































Appendix O

376











































Appendix P Costs of Wastewater Reclamation Systems

Appendix P

378


Wastewater treatment system – Reuse 1


1. WASTEWATER COLLECTION PIPEWORK R$ 971.70




2. WASTEWATER DRAINAGE PIPEWORK R$ 951.85




3. WASTEWATER TREATMENT SYSTEM R$ 18,150.00

3.1. Wastewater treatment station R$ 16,500.00


4. TREATED WASTEWATER DISTRIBUTION PIPEWORK R$ 270.20











1.2. Wastewater treatment system 300 W 4380 hr/yr R$ 0,30 kwh R$ 394.20



Appendix P

379




1. WASTEWATER COLLECTION PIPEWORK R$ 1,040.20








3. WASTEWATER RECYCLING SYSTEM R$ 18,150.00



4. TREATED WASTEWATER DISTRIBUTION PIPEWORK R$ 2,345.55




























Appendix P

380





























Appendix P

381







































1.2. Distribution water pump 1hp 1300W 2731 hr/yr

R$ 0,30 kwh R$ 368.69

1.3. Greywater treatment system 300 W 8760 hr/yr

R$ 0,30 kwh R$ 788.40



Appendix P

382





























Appendix P

383











































Appendix P

384





1.1. 3m PVC gutter 132x89 1 R$ 51.25 R$ 51.25





























TOTAL COST R$ 4.78

A socio-technical study of water consumption and water conservation in Brazilian dwellings

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Transcript of A socio-technical study of water consumption and water conservation in Brazilian dwellings