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How much water did you use in 2021? This index might answer that question
Environment Feb 02, 2022
| Photo courtesy of Martin Vorel/LibreShot
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Flume, the company that brings connectivity and intelligence to household water use, released the 2021 Flume Household Water Use Index, the leading measure of U.S. household water use.
Flume assessed water use across the top 15 Metropolitan Service Areas (MSAs) throughout 2021 based on data from tens of thousands of Flume devices installed on household water meters across the nation. Flume publishes the Household Water Use Index quarterly.
National Indoor Per Capita Water Use
Nationally, indoor water use continues to increase in efficiency. Indoor Household Water Use averaged 41.4 Gallons per Capita per Day (GPCD) in Q4 2021 which was lower than the 2021 annual average of 44.7 GPCD. Average water use in 2020 was 50.1 GPCD
Indoor water use efficiency in 2021 continued to increase after the peak in indoor water use following the outbreak of COVID in 2020. On a national scale, the lingering impacts of increased indoor use appear to be over and water use has even fallen below pre-COVID averages. Even as average indoor use has declined, additional room for indoor efficiency remains for many households with usage above 40 GPCD. Many homes today equipped with efficient fixtures and appliances use 30 – 35 GPCD on average.
Indoor Per Capita Use by Metro Area in 2021
The Flume Index also includes indoor per capita use for the 15 most populous Metropolitan Statistical Areas (MSA) in the US. In 2021 the San Francisco MSA, which includes the greater SF Bay area, had the lowest indoor use, with an average of 37.9 GPCD. The Phoenix MSA had the highest indoor use per capita in 2021 with an average of 52.6 GPCD.
National Outdoor Household Water Use in 2021
Outdoor Household Water Use averaged 173.1 Gallons per Household per Day (GPHD) in 2021. This is a significant decrease from 2020 when outdoor use averaged 216.8 GPHD. In 2021 the Boston MSA had the lowest average outdoor use at 57.0 GPHD and the Phoenix MSA had the highest outdoor use at 337.7 GPHD, reflecting the differences in weather patterns and water requirements.
Efficiency Level of American Toilets and Showers
In addition to reviewing water use in 2021, Flume analyzed December 2021 water use in high resolution, using signal processing approaches with machine learning. The resulting data set of end uses, including showers and toilet flushes, contains millions of records and is the largest assembled to date far exceeding previous end-use research.
Flume measured the average toilet flush volume to be 2.0 gallons per flush based on an analysis of more than 11.1 million flushes across tens of thousands of households. The median flush volume was 1.6 gallons.
The average shower used 11.4 gallons, lasted 6.6 minutes and was taken at an average flow rate of 1.7 gallons per minute. These numbers show the continued efficiency improvement in toilets and showers since 1999 and 2016 levels measured in the Water Research Foundation’s Residential End Uses of Water.
Flume also assessed the efficiency of showers and toilets by home age. Examining homes built from 1950 to 2020, Flume found that, on average, home age does not impact efficiency. Homes built in 1950 are equally as efficient as new homes built. However, there is a marked increase in efficiency in brand new buildings constructed in or after 2007.
“Indoor use varies considerably by region, but overall it has become more efficient across America,” said Peter Mayer, P.E., Principal of WaterDM, an expert consultant to the water industry for more than 25 years. “Flume Data shows the measurable differences in water use patterns across the US cities and add to our understanding of the demand reductions that have been achieved to date through efficient fixtures and appliances.”
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