Residential End Uses of Water

Transcription

1 AWWA Research Foundation Residential End Uses of Water Subject Area: Water Resources

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3 Residential End Uses of Water

4 The mission of the AWWA Research Foundation is to advance the science of water to improve the quality of life. Funded primarily through annual subscription payments from over 1,000 utilities, consulting firms, and manufacturers in North America and abroad, AWWARF sponsors research on all aspects of drinking water, including supply and resources, treatment, monitoring and analysis, distribution, management, and health effects. From its headquarters in Denver, Colorado, the AWWARF staff directs and supports the efforts of over 500 volunteers, who are the heart of the research program. These volunteers, serving on various boards and committees, use their expertise to select and monitor research studies to benefit the entire drinking water community. Research findings are disseminated through a number of technology transfer activi ties, including research reports, conferences, videotape summaries, and periodicals.

5 Residential End Uses of Water Prepared by: Peter W. Mayer and William B. DeOreo Aquacraft, Inc. Water Engineering and Management 2709 Pine St., Boulder, CO Eva M. Opitz, Jack C. Kiefer, William Y. Davis, and Benedykt Dziegielewski Planning and Management Consultants Ltd. Box 1316, Carbondale, IL John Olaf Nelson John Olaf Nelson Water Resources Management 1833 Castle Drive, Petaluma, CA Sponsored by: AWWA Research Foundation 6666 West Quincy Avenue Denver, CO Published by the AWWA Research Foundation and American Water Works Association

6 Disclaimer This study was funded by the AWWA Research Foundation (AWWARF). AWWARF assumes no responsibility for the content of the research study reported in this publication or for the opinions or statements of fact expressed in the report. The mention of trade names for commercial products does not represent or imply the approval or endorsement of AWWARF. This report is presented solely for informational purposes. Residential end uses of water / prepared by Peter W. Mayer and William B. DeOreo... [et al.]: sponsored by AWWA Research Foundation, xxxviii, 310 p. 21.5x28 cm. Includes bibliographical references (p. ). ISBN Water consumption United States Databases. 2. Water consumption United States Statistics. I. Mayer, Peter W. n. DeOreo, William B. ffl. AWWA Research Foundation. TD223.R '13' dc CIP Copyright 1999 by AWWA Research Foundation and American Water Works Association Printed in the U.S.A. ISBN , Printed on recycled paper.

7 CONTENTS LIST OF TABLES... xi LIST OF FIGURES...xv FOREWORD... xvii ACKNOWLEDGMENTS... xix EXECUTIVE SUMMARY....xxi CHAPTER 1 INTRODUCTION... 1 Project Team How to Use This Report...4 CHAPTER 2 LITERATURE REVIEW...6 CHAPTER 3 RESEARCH APPROACHES AND PROCEDURES...11 Overview of Research Process Study Site Selection Initial Survey Group Sample...16 Survey Development and Implementation...19 Survey Design Use of KEYCODE to Preserve Customer Anonymity...20 Survey Implementation...21 Study Group Selection...22 Comparison of Survey Respondents with Survey Targets and Non -respondents.22 Selection of Data Logging Sample...24 End Use Data Collection...27 Data Logging Equipment...27 Logger Installation...29 Data Collection Schedule...30 End Use Data Analysis...31 Flow Trace Analysis...31 Meter-Master Data Loggers Trace Wizard...33

8 Database Development...38 Working Categories for Disaggregation...39 Supplemental Data Collection...40 Weather Data...40 Conservation Program Data and Price and Rate Structure...41 Quality Assurance and Quality Control...42 Accuracy of Flow Trace Analysis...43 CHAPTER 4 COMPARISON OF STUDY SITES Utility Service Area Characteristics...48 Water and Sewer Rates Utility Sponsored Conservation Programs and Local Conservation Regulations. 5 8 Information from Billing Data...58 Annual Use Patterns...60 Seasonal Water Use...63 Survey Responses...67 Survey Response Rate Comparison of Survey Responses Across Study Sites...69 CHAPTER 5 END USE DATA ANALYSIS...82 Daily Household Use Total Daily Use...83 Daily Indoor Use Indoor Per Capita Use...86 Mean Per Capita Daily Water Use Study Site Comparison Leaks Fixture Utilization Per Capita Per Day...94 Toilets...96 Clothes Washers Analysis of Variance in Indoor Water Use Outdoor Use Ill Irrigated Area Update vi

9 Outdoor Use and ET Irrigable Area and Application Rate Variability in Outdoor Water Use Peak Use Peak Instantaneous Demand Peak Day Demand Water Pressure Delivery Ranges Hourly Use Comparison of REUWS Results with Other Studies Per Capita Per Day Comparison Fixture Utilization Comparison Conservation Effectiveness Ultra-Low-Flush Toilets Low-Flow Showerheads Landscape Measures Additional Conservation Potential CHAPTER 6 STATISTICAL MODELS OF END USE MEASUREMENTS Introduction Survey Characteristics of the Data Logging Sample Price of Water and Sewer Omitting Weather and Seasonality from End Use Models Inferential Analysis Toilet Use Shower and Bath Use Faucet and Water Treatment System Use Dishwasher Use Clothes washer Use Leaks Outdoor Use Other/Unknown Use Predictive Analysis Estimated System of End Use Models vii

10 Applying End Use Models: An Example Comparison of Logged Use with End Use Model Predictions Extending the End Use System to Predict Total Use CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS Conclusions Annual Use Daily Per Capita Use Peak Use Hourly Use End Use Models Modeling Conclusions Recommendations Modeling Recommendations APPENDIX A RESIDENTIAL END USES OF WATER SURVEY Detailed Survey Group Selection Procedures Instructions for Handling Survey Forms Suggested Cover Letter for Water Survey Residential Water Use Survey Survey Follow-up Postcard Survey Follow-up Letter to Non-Respondents Survey Implementation Schedule Sample Water Survey Input Form Draft Notice (Consent) Letter Complete Mail Survey Responses APPENDIX B QUALITY ASSURANCE AND QUALITY CONTROL Description of Eight Major Quality Assurance and Quality Control Tests QATest 1 -Test Validity of Service Address QA Test 2 - Test to See if 1,000 Sample is Representative QA Test 3 - Check Accuracy of Survey Response Data Entry Process QA Test 4 - Test if Water Use of Survey Respondents is Representative QA Test 5 - Test if 150 Sites Selected for Logging are Representative QA Test 6 - Test Data Logger to See that it is Recording Properly viii

11 QA Test 7 - Check Accuracy of Data Logger vs. Meter QA Test 8 - Check Accuracy of Event Database QA Test Forms QATest 1 -Test Validity of Service Address QATest 3 - Check Accuracy of Survey Response Data Entry Process QA Test 6 Data Logger Installation and Removal QA Test 7 Check Logger vs. Meter Volumes QA Test 8 Check Accuracy of Event Database APPENDIX C THE RESIDENTIAL END USES OF WATER STUDY DATABASE Database Structure Database Tables Logging Data Daily Use Survey Responses Using the REUWS Database Billing data Survey Response Data How to Obtain the REUWS Database APPENDIX D RESIDENTIAL END USE MODELS Statistical Model of Average Total Household Use Model Estimation Procedure Scale Correction for Interpreting Coefficients of Binary Variables Interpretation of Total Household Use Model Development of Inferential Models Estimation Procedure for Inferential Models IX

12 Model Specification and Selection Development of Predictive System of End Use Equations Estimation Approach The Seemingly Unrelated Regression (SUR) Procedure Extending End Uses Models to Predict Total Monthly Use Estimation Process and Results Example Application of End Use Model Developing Predictions of Indoor and Outdoor Use REFERENCES ABBREVIATIONS...308

13 TABLES 3.1 Sample comparisons for survey and logging groups Dates of data collection Bucket test results Water and sewer rates during logging periods Conservation measures implemented by participating utilities Annual water use statistics from initial survey samples Climate data and outdoor use, 12 study sites Survey response rates Mail survey question categories Mean, median, and mode number of toilets, baths, and showers from mail survey Saturation of dishwashers and clothes washers from mail survey Saturation of evaporative coolers and water treatment systems Mean number of residents in winter and summer Comparison of daily per capita indoor water use Comparison of daily per capita leakage rates Fixture utilization per capita per day, mean and standard deviation Fixture utilization per capita per day Toilet flush volume, per capita use, and utilization Shower per capita use, volume, duration, and flow rate Per capita clothes washing use Average indoor gallons per capita per day usage Percentage of average indoor gallons per capita per day usage Toilet statistics in cities with significantly different per capita usage Shower statistics in cities with significantly different per capita usage Statistical comparison of indoor use between logging periods Outdoor use using different estimation techniques Annual indoor, outdoor, and total use for the logging samples Irrigable area and application rate Water pressure ranges in distribution systems XI

14 5.17 Indoor gallons per capita per day water use in previous studies and the REUWS Fixture utilization values from REUWS and previous studies ULF and non-ulf toilet use across 12 study sites Comparison of ULF savings from other studies LF and non-lf daily shower use Comparison of LF showerhead savings from other studies Reported socioeconomic and home property summary, from survey Reported presence or absence of end use, from survey Reported irrigation technology, from survey Reported conservation measures, from survey Weather and climate patterns during logging periods Trace-allocated (and predicted) daily end use for logged Comparison of observed and predicted average daily water use Comparison of observed and predicted average daily water use A.I Complete survey response summary, 14 study cities B.I QA test 1 results B.2 QA test 2 results B.3 QA test 3 results B.4 QA test 4 results B.5 QA test 5 results B.6 QA test 6 results B.7 QA test 7 results B.8 QA test 8 results C.I Keycode definitions D. 1 OLS Model of household billing data water use D.2 Toilet water use model D.3 Shower and bath water use model D.4 Faucet water use model D.5 Dishwasher water use model D.6 Clothes washer water use model D.7 Leak water use model D.8 Outdoor water use model xn

15 D.9 Other/unknown water use model D. 10 SUR model - cross model correlation between end uses D.I 1 SUR model - ln(logged toilet use in gallons per day) D.12 SUR model - ln(logged faucet/treatment use in gallons per day) D. 13 SUR model - ln(logged shower/bath use in gallons per day) D. 14 SUR model - ln(logged dishwasher use in gallons per day) D. 15 SUR model - ln(logged clothes washer use in gallons per day) D.16 SUR model - ln(logged leak use in gallons per day) D.17 SUR model - ln(logged outdoor use in gallons per day) D. 18 SUR model - ln(logged other/unknown use in gallons per day) D.I 9 Adjusted billing model of household water use D.20 Adjusted billing model look-up table xin

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17 FIGURES ES.l Mean daily per capita water use... xxv ES.2 Indoor per capita water use percent... xxvi ES.3 Peak instantaneous water use... xxx ES.4 Hourly use patterns... xxxi ES.5 Indoor hourly use patterns...xxxii 3.1 Residential End Uses of Water Study flow chart Residential End Uses of Water Study sites One of the 110 data loggers used in the study Brainard datalogger in the meter pit Sample flow trace from Trace Wizard showing a one hour Sample flow trace from Trace Wizard showing a two hour view Sample flow trace from Trace Wizard showing a six hour view Sample flow trace from Trace Wizard showing a two hour view Sample flow trace showing a one hour view Sample flow trace analysis comparison form Participating house in Boulder, Colorado Participating house in Denver, Colorado Participating house in Eugene, Oregon during data logger installation Participating house in Seattle, Washington Participating house in Tampa, Florida and Tampa Water employee Philip Elkins Participating house in Waterloo, Ontario Participating house in Phoenix, Arizona Participating house in Scottsdale, Arizona during data logger installation Participating house in San Diego, California during data logger installation Participating house from the Walnut Valley Water District, California Participating house in Lompoc, California Participating house from Las Virgenes Municipal Water District Annual water use distribution, 12 REUWS study sites, 12,055 homes Box plot of per household annual water use Net annual ET for turf vs. mean annual per household outdoor use...65 xv

18 4.16 Typical survey response curve Swimming pool and hot tub saturation rates, all study cities Highest level of educational attainment, all study cities Combined household income, all study cities Percent of homes irrigating 3 times per week or more, all study cities Conservation importance, all study cities Perception of drought, all study cities Scatter diagram of average daily water use Box diagram of average daily water use Scatter diagram of average daily indoor water use Box diagram of average daily indoor water use Indoor per capita water use percentage including leakage Average per capita per day usage (gpcd) Distribution of mean household daily per capita indoor water use Indoor water use by household size Distribution of mean daily leakage Toilet flush distribution, all recorded toilet flushes Shower volume distribution diagram Shower duration distribution Shower flow rate distribution Clothes washer volume per load distribution Outdoor use vs. net ET Irrigation application rate vs. net ET Histogram of percent of net ET applied to irrigable area Scatter diagram of irrigation application rates vs. net ET Peak instantaneous flow rate distribution Distribution of peak logged day demand Hourly use pattern, averaged for all 12 study sites Disaggregated indoor hourly use patterns, averaged across 12 study sites Analytical process of model development and verification Process of extending end use models to predict average total monthly use A.I Sample survey input form xvi

19 FOREWORD The AWWA Research Foundation is a nonprofit corporation that is dedicated to the implementation of a research effort to help utilities respond to regulatory requirements and traditional high-priority concerns of the industry. The research agenda is developed through a process of consultation with subscribers and drinking water professionals. Under the umbrella of a Strategic Research Plan, the Research Advisory Council prioritizes the suggested projects based upon current and future needs, applicability, and past work: the recommendations are forwarded to the Board of Trustees for final selection. The foundation also sponsors research projects through the unsolicited proposal process; the Collaborative Research, Research Applications, and Tailored Collaboration programs; and various joint research efforts with organizations such as the U.S. Environmental Protection Agency, the U.S. Bureau of Reclamation, and the Association of California Water Agencies. This publication is a result of one of these sponsored studies, and it is hoped that its findings will be applied in communities throughout the world. The following report serves not only as a means of communicating the results of the water industry's centralized research program, but also as a tool to enlist the further support of the nonmember utilities and individuals. Projects are managed closely from their inception to the final report by the foundation's staff and large cadre of volunteers who willingly contribute their time and expertise. The foundation serves a planning and management function and awards contracts to other institutions such as water utilities, universities, and engineering firms. The funding for this research effort comes primarily from the Subscription Program, through which water utilities subscribe to the research program and make an annual payment proportionate to the volume of water they deliver and consultants and manufacturers subscribe based on their annual billings. The program offers a cost effective and fair method for funding research in the public interest. A broad spectrum of water supply issues is addressed by the foundation's research agenda: resources, treatment and operations, distribution and storage, water quality and analysis, toxicology, economics, and management. The ultimate purpose of the coordinated effort is to assist water suppliers to provide the highest possible quality of water economically and reliably. The "end uses" of water is a fundamental planning issue. Water conservation and resource planners need an accurate picture of how consumers use water. Engineers rely upon xvii

20 end use information to identify design capacity and other engineering parameters. Most existing end use information is extremely site specific and often of little value outside of a particular region. Unfortunately, engineers and planers are left to estimate end uses without the basis of sound analytical data. This project developed an extensive database of end use information. The database was developed using sophisticated data logging techniques and computer based analytical models. From the data and models, accurate end uses of water estimates were developed. Julius Ciaccia, Jr. James F. Manwaring, P.E. Chair, Board of Trustess Executive Director AWWA Research Foundation AWWA Research Foundation xvm

21 ACKNOWLEDGMENTS This research would never have been completed without the cooperation of more than 5,000 households across the continent who completed mail surveys and the 1,200 households that agreed to participate in the detailed end use study. Our heartfelt thanks to each and every one. This research project was made possible by AWWARF and the following municipalities and water providers: City of Boulder Office of Water Conservation, Denver Water, Eugene Water and Electric Board, Seattle Public Utilities, Northshore Water District, Highline Water District, Bellevue Water Department, City of San Diego Water, Tampa Water Department, Phoenix Water Department, Tempe and Scottsdale Water Departments, Regional Municipality of Waterloo, Walnut Valley Water District, Las Virgenes Municipal Water District of Southern California, City of Lompoc, Metropolitan Water District of Southern California, Southwestern Florida Water Management District, Arizona Municipal Water Users Association, Santa Barbara County Flood Control and Water Conservation District and Water Agency, California Department of Water Resources, Sonoma County Water Agency, North Marin Water District. The project team wishes express our sincere thanks to the following individuals and groups for their assistance on this project: David Lewis, Laurel Stadjuhar, Jeff Harpring, Beorn Courtney, Mark Alexander, Eric Loew, Paul Lander, Bob Harburg, Don Vetterling, Jim Heiser, Edward Pokorney, John Loughrey, David Alien, Steve West, Brenda Sirois, Richard Head, Al Dietemann, Tim Skeel, Fanny Yee, Patricia Burgess, Steve Wieneke, Judy Burdin, Jim Echert, Kirn Drury, Marsi Steirer, Luis Generoso, Kathy Fry, Arnold Niemann, Robert Lauria, Phillip Elkins, Tom Babcock, Andy Terry, Lisa Helm, Vonnie Caraballo, Karen Warner, Oliver Ncube, Pete Smith, Ken Sharratt, Deborah Walker, Scan Smith, Derek Berkhout, Darcy Jones, James Robinson, Denis Hernandez, Scott Harris, Randall Orton, Lynn Anderson-Rodriguez, Charlie Pike, Gary Keefe, Susan Zavolta, Mario Villareal, Jim Heaney, Tony Gregg, Bill Hoffman, Dan Rodrigo, Cathy Pieroni, Barbara Nadon, Warren Teitz, Mike Hollis, Cliff Pugh, John Balliew, John Sweeten, Ed Craddock, Robert Almy, Chris DeGabriele, Bill Jacoby, George Martin, John Wiedmann, John Flowers, Randy Poole, Robert Alien, the AWWA Water Conservation Planning and Evaluation Committee and the AWWA Water Conservation Divisio'n Board. xix

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23 EXECUTIVE SUMMARY Where is water used in single-family homes? How much water is used for toilets, showers, clothes washers, faucets, dishwashers, and all other purposes? What component of total use can be attributed to each specific water using device and fixture? How does water use vary across single-family homes? What are the factors that influence single-family residential water use? How does water use differ in households equipped with conserving fixtures? The Residential End Uses of Water Study (REUWS) was designed to help answer these and other questions and to provide specific data on the end uses of water in single-family residential settings across North America. The "end uses" of water include all the places where water is used in a single-family home such as toilets, showers, clothes washers, faucets, lawn watering, etc. Accurately measuring and modeling the residential end uses of water and the effectiveness of conservation efforts has been the Achilles heel of urban water planning for many years. Understanding where water is put to use by the consumer is critical information for utilities, planners, and conservation professionals. Empirical evidence of the effectiveness of specific conservation measures can be used to improve the design of conservation programs and can provide justification for continued support of conservation efforts. RESEARCH OBJECTIVES The American Water Works Association Research Foundation (AWWARF) and 22 municipalities, water utilities, water purveyors, water districts, and water providers funded this study. Goals of this research included: Providing specific data on the end uses of water in residential settings across the continent. Assembling data on disaggregated indoor and outdoor uses. Identifying variations in water used for each fixture or appliance according to a variety of factors. Developing predictive models to forecast residential water demand. xxi

24 This report represents a time and place snapshot of how water is used in single-family homes in twelve North American locations. Similarities and differences among "end uses" were tabulated for each location, analyzed, and summarized. Great care was taken to create a statistically significant representative sample of customer for each of the twelve locations. However, these twelve locations are not statistically representative of all North American locations. Although a concerted effort was made to recruit a representative sample of households at each location, some households chose not to participate. While this may place some limits on the statistical inferences and generalizations which can be drawn from the data, it does not diminish the contribution made by these data to improving understanding of residential water use. Analyses are presented for each of the participating cities individually and for the pooled sample of 1,188 households. Creating national water use "averages" was not an objective of this study. The pooled results are presented for summary and comparative purposes alone. Two major contributions of this study are demonstrating the feasibility of identifying and measuring the different ways households use water and describing and analyzing variations in water used for specific purposes between different households. Armed with this insight, individual water utilities interested in reducing water demands in single-family homes now have a better tool to assess their own conservation potential. The diversity of the water use data found over the twelve locations illustrates the importance of utility specific information on how individual behavior influences home water use. However, a striking conclusion of this report is in the similarities between these twelve locations in the amount of water fixtures and appliances use. The range in the amount of water used by hardware such as toilets, washing machines, showerheads, dishwashers, faucets, and fixture leaks is now documented and surprisingly similar - suggesting that this portion of the data has significant "transfer" value across North America. The predictive models developed as part of this study to forecast indoor demand significantly increase the confidence in explaining the water use variations observed. The major benefit of modeling is to provide a predictive tool with a high transfer value for use by other utilities. xxn

25 APPROACH The project team developed a multifaceted approach to accomplish the research objectives set out for this study. After invitations were sent to utilities and water providers across the United States and Canada, 12 study sites volunteered to participate and partially fund this research. These 12 study sites were: Boulder, Colorado; Denver, Colorado; Eugene, Oregon; Seattle, Washington; San Diego, California; Tampa, Florida; Phoenix, Arizona; Tempe and Scottsdale, Arizona; the Regional Municipality of Waterloo, Ontario; Walnut Valley Water District, California; Las Virgenes Municipal Water District, California; and Lompoc, California. A detailed and rigorous workplan to obtain data from each study site was developed by the project team. Data collected from each study site included: historic billing records from a systematic random sample of 1,000 single-family detached residential accounts; household level information obtained through a detailed mail survey sent to each of the selected 1,000 households; approximately four weeks of specific data on the end uses of water collected from a total of 1,188 households (approximately 100 per study site), data collection was divided into two, two-week intervals spaced in time to attempt to capture summer (peak) and winter (off-peak mostly indoor water use) time frames; supplemental information including climate data and information specific to each participating utility. In this study, water consumption for various end uses was measured from a significant sample of residential housing across North America using compact data loggers and a PC-based flow trace analysis software. A flow trace is a record of flow through a residential water meter recorded in 10 second intervals which provides sufficient resolution to identify the patterns of specific fixtures within the household. The flow trace analysis software disaggregates this virtually continuous flow trace into individual water use events such as a toilet flush or clothes washer cycle and then an analyst implements signal processing tools to assign fixture designations to each event. The data assembled for this research effort include: A sizable residential water use database containing nearly one million individual water use "events" collected from 1,188 residences in the 12 study sites; extensive household level information obtained through the mail survey completed by approximately 6,000 households, and historic water billing records from 12,000 residences. All of this information was collected to provide answers to many long xxm

26 standing questions about how much and where water is used in the residential setting and to provide estimates of the savings available from various conservation measures. In addition to presenting the findings from the data collection effort, the project team also developed predictive models which incorporated the detailed end use information and household level socioeconomic data. A research study of this magnitude must rely on a variety of assumptions which are taken as "givens". It is recognized that changes in some of these assumptions could impact the results, but the limits of the project scope and funding did not allow exploration of some of the following factors: 1. The accuracy of the billing consumption histories provided by participating utilities 2. The accuracy of mail survey responses 3. The timeframe of monitoring capturing "representative" indoor water use for each home 4. Capturing the precise weather related use within the monitoring timeframe needed to analyze the variables associated with outdoor use RESEARCH FINDINGS The primary goal of this study was to provide specific data on the end uses of water in residential settings across the continent. The accomplishment of this and the other stated goals of the REUWS are summarized in the findings below. Annual Use Average annual water use, based on historic billing records from approximately 1,000 accounts in each of the 12 study sites, ranged from 69,900 gallons per household per year in Waterloo and Cambridge, Ontario to 301,100 gallons per household per year in Las Virgenes MWD. The mean annual water use for the 12 combined sites was 146,100 gallons per household per year with a standard deviation of 103,500 gallons and a median of 123,200 gallons (n= 12,075). Across all study sites 42 percent of annual water use was for indoor purposes and 58 percent for outdoor purposes. This mix of indoor and outdoor was strongly influenced by annual weather patterns and, as expected, sites in hot climates like Phoenix and Tempe and xxiv