Study: Efficient fixtures have cut U.S. indoor water use 22% since 1999

Indoor household water use in the United States decreased 22 percent between 1999 and 2016, according to the most rigorous analysis to date of how water is used in U.S. homes.

Even more encouraging for conservationists is that indoor water use could drop another 35 percent or more if all homes installed the most water-efficient fixtures and appliances on the market.

The decline in water use — from 670 liters (177 gallons) per household per day to 522 liters (138 gallons) — is not due to a green wave of environmentalism breaking over the suburbs. U.S. households accomplished the feat without a significant change in behavior, according to William DeOreo, lead author of the study. Household size was roughly equal in the two studies (2.7 people in 1999 versus 2.6 today). Minutes per shower remained constant. Toilet flushes did not budge. Neither did faucet use. The reason households are using less water: better equipment.

“It’s almost all attributable to fixtures,” DeOreo told Circle of Blue, talking about toilets, faucets, clothes washers, dishwashers, and other appliances. “It’s not like people’s habits changed. Better technology really drove the reduction. And there’s room for more improvement if we adopt the best technology out there today.”

The study’s findings are consistent with broader water use patterns in the United States. Water withdrawals peaked in 1980, according to U.S. Geological Survey data. In addition, many cities, while confronting limits to water supply, are seeing persistent downward trends in consumption. Fort Worth, Texas, for instance, cut residential water use by 18 percent between 2006 and 2013. And Seattle uses about 30 percent less water today than in the late 1980s.