Residential End Uses of Water, Version 2
About this book
Residential End Uses of Water, Version 2 (2016), published by the Water Research Foundation (WaterRF, formerly AwwaRF — American Water Works Association Research Foundation), is the most comprehensive North American study of how residential customers use water inside and outside the home. Based on metered hourly data from 762 households across 9 US cities collected using smart meter technology, this second edition updates the landmark 1999 study with higher-resolution data and expanded analysis of conservation programme effects. The study uses smart meter data (15-minute resolution) disaggregated through end-use disaggregation software (REUWS methodology) to assign individual water-using events — toilet flushes, shower events, clothes washer cycles, faucet use, outdoor irrigation — to specific fixture categories.
This event-level analysis allows precise characterisation of per-capita water use by end use, time of day, day of week, and season, providing the empirical foundation for conservation target-setting, demand forecasting, and rate design. Key findings update and refine the 1999 baseline. Average indoor per-capita residential water use was 69.3 gallons per person per day (262 litres per person per day), essentially unchanged from the 1999 study despite the widespread replacement of older high-consumption fixtures with low-flow toilets and showerheads.
This apparent paradox is explained by the dramatic increase in homes with dishwashers and clothes washers: the efficiency gains from fixture replacement have been partially offset by the expansion of appliance ownership. Toilet flushing remains the largest single indoor use at approximately 24% of total use (16.8 gallons per capita per day), followed by clothes washers (21.7%), showers (16.8%), faucets (15.7%), leaks (11.6%), baths (3.7%), dishwashers (1.4%), and other uses. Outdoor water use — primarily landscape irrigation — averages approximately 30% of total residential water use annually, but exhibits extreme seasonal variability (reaching 60-70% of total use in summer months in arid climates).
The study documents significant demographic and seasonal variation. High-efficiency plumbing customers (WaterSense labelled fixtures throughout) used approximately 30% less water than baseline customers, providing empirical support for water utility rebate programmes. The data is extensively used by water utility planners for water conservation potential assessments and by researchers modelling residential water demand response to pricing signals.