Study: Lawns soak up half of the average home's water use

About half of the typical home's daily water use goes toward outdoor purposes, according to a recent analysis by the National Association of Home Builders.

The average single-family home in the United States uses 276.2 gallons of water per day. Of this amount, 138.4 gallons—50.1 percent—is used for outdoor purposes such as watering lawns or filling a swimming pool.

Toilets account for the largest share of indoor water use, flushing away 33.1 gallons of water per day in an average home. This makes up 24 percent of the typical home's indoor water use and 12 percent of the home's total water use.

The average home's daily water use also includes 28.1 gallons used for showering, 26.3 gallons drawn from faucets, and 22.7 gallons used in a clothes washer. Bathtubs only account for 3.6 gallons per day on average, while the typical home uses just 1.6 gallons for a dishwasher. The typical home also loses 17 gallons per day to leaks, although the report attributes this average to substantial leaks in a relatively small share of homes.

The 138.8 gallons per day typically used for indoor water use was down from a figure of 177 gallons per day recorded in 1999. Faucet use was the only area that did not see a reduction.

The study attributed this drop in water use to the increasing prevalence of water-saving appliances after 1999. For example, 80 percent of homes built after 1999 have an Energy Star rated clothes washer, compared to 63 percent in homes built before 1950. Seventy-one percent have toilets that used 1.6 gallons or less per flush and 51 percent have toilets using 1.28 gallons or less per flush, compared to 63 percent and 38 percent, respectively, in homes built prior to 1950.

However, newer homes were not necessarily more efficient than older ones. The average single-family home built in the 1960s uses 244 gallons per day, while the typical home built after 1999 uses 251 gallons per day.

The NAHB says that while new homes are more likely to have water-saving appliances and devices, they also tend to have more features that use water. Newer homes usually have more bathrooms, with the share of single-family homes having at least two bathrooms rising from 60 percent of residences completed in 1973 to 97 percent of homes completed in 2016. Newer homes are also more likely to have features such as multiple showerheads, body spray panels in the shower, water softeners, or water filtration systems.

In addition, outdoor water features are more common in newer homes. Two-thirds of residences built after 1999 have an in-ground sprinkler, while 12 percent have a swimming pool. By contrast, 35 percent of homes built before 1950 feature an in-ground sprinkler system while just 3 percent have a swimming pool.

Water use varies considerably based on the region. Areas with drier climates, low amounts of natural rainfall, and larger households tend to use more water per day. Nevada is the most prominent water user, with the typical single-family household using 472 gallons of water per day. Maine has the lowest average daily water use at 100 gallons per day.

The typical Connecticut household uses 180 gallons per day. Rhode Island homeowners uses 163 gallons per day on average.

According to information from the Department of the Interior, 355 billion gallons of water are used in the United States each year. More than half of the water used by public suppliers, such as utilities, is delivered to residences.

However, residential use only accounts for 7.7 percent of all water use in the U.S. The majority—45.4 percent—is used for thermoelectric power such as steam-driven turbines. Another 32.4 percent of water use goes toward irrigation of crops, parks, golf courses, and other land.

The NAHB analysis used data from the Water Research Foundation, which released its Residential End Uses of Water study in 2016. This research included billing data provided by 20 water utilities, flow trace devices installed on 800 participating homes, and 13,732 responses to a survey presented to single-family homeowners.

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