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Water Research Foundation Releases Updated Residential End Use Study

The comprehensive update confirms that indoor water use per household continues to decline.  

The Water Research Foundation (WRF), a leading sponsor of research supporting the water community, is pleased to announce the results from Residential End Uses of Water, Version 2 (project #4309). This project serves as a comprehensive update to WRF's 1999 Residential End Uses of Water study. This project focused solely on single-family residences. Some key findings of the study are as follows: 

  • Residential indoor water use in single-family homes has decreased 22% since WRF's 1999 study, from 177 gallons per household per day (gphd) to 138 gphd. 
  • Toilet flushing is the largest indoor use of water in single-family homes, followed by faucets, showers, clothes washers, leaks, bathtubs, other indoor uses, and dishwashers. 
  • The current average daily indoor per household use of 138 gphd could decrease to 110 gphd with full adoption of water-efficient fixtures. 
  • Forty-six percent of homes in the new study had water-efficient clothes washers, compared to 6% in 1999, and 37% of the participating homes had efficient toilets, compared to 5% in 1999. 
  • Household hot water use accounted for 33% of total indoor water use. 
  • Regarding outdoor water use, analyzing the trends and efficiency in water use from landscaping and pools is more complex because of varied climatic regions and variations in plantings at each house. At a high level analysis, this study found that while a minority of users are overwatering, most are not.   

Single-family homes typically use the most water of any utility customer sector in North America. This study definitively demonstrates that indoor water use per household in North America is declining. The primary reason for this decline is the installation of water efficient appliances throughout the home. Information on single family home water consumption is significant for utility rate and revenue projections, water supply and infrastructure needs, daily operations, water efficiency programs, and more. 

The decline in indoor per household water use poses new challenges for water utilities as increasing population does not necessarily result in a proportional increase in water used. This challenge is coupled with the other complexities that utilities have to consider like the increasing costs to maintain and repair buried infrastructure and the increasing costs of personnel. 

"Society benefits from water efficiency, but many water utility costs are fixed regardless of water use," said Rob Renner, CEO of the Water Research Foundation. "It's crucial for the water community to build a sustainable business model within the paradigm of declining water use." 

The new study includes data from 23 participating utilities across the United States and Canada, and presents detailed information and data about how residential water use has changed since 1999. This update includes more varied site locations, hot water end use data, more detailed landscape analysis, and expanded water rates analysis. Deliverables include an Executive Report (4309A), a full report (4309B), and an Access Database. The database contains all of the end use water events recorded during the 2016 study, along with the survey response data, historic billing data, and other data obtained for each study site. The database also contains summary results from other end use studies. This resource can be utilized by researchers and WRF subscribers as a jumping off point for further research. 

This study was jointly funded by the Water Research Foundation, City of Fort Collins Utilities, City of Scottsdale Water Department, Clayton County Water Authority, Denver Water, Region of Waterloo, Tacoma Public Utilities, Toho Water Authority, and the Alliance for Water Efficiency on behalf of Portland Water Bureau, Region of Peel, San Antonio Water System, and Tampa Bay Water.

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