How much water do you actually use?

It turns out that most people aren’t very good at answering that question. According to a new study, people tend to think their water use is about half the actual amount.

Americans are water hogs: On average, each person used nearly 100 gallons per day in 2005, even though only about 13 gallons are needed for basic activities such as drinking and cleaning. And “[m]ost Americans assume that water supply is both reliable and plentiful,” writes researcher Shahzeen Attari of Indiana University in Bloomington in the Proceedings of the National Academy of Sciences. But we could be in for a rude awakening. Climate change will make rain- and snowfall more variable, and that steady flow from the tap could slow to a trickle.

To find out whether people realized how much water they were using, Attari surveyed 1,020 Americans online. She asked people to estimate the amount of water needed for 17 activities such as flushing a toilet, taking a shower, or using a garden hose. She also asked what they thought would be the most effective way to cut water use.

Respondents did know that certain activities were more water-intensive — for example, that a Jacuzzi guzzles more water than a dishwasher. But on average, they thought each activity used only about half the water that it actually did. They also didn’t have a good sense of whether certain foods required more water to produce than others.

About three-quarters of participants thought that the best way to cut their own water use was to limit or shorten certain activities, such as taking showers. Few mentioned upgrading to more water-efficient toilets, even though the Environmental Protection Agency considers this measure far more effective. People might not consider installing more efficient fixtures because they think it’s too expensive, Attari suggests. Roberta Kwok | 4 March 2014

Source: Attari, S.Z. 2014. Perceptions of water use. Proceedings of the National Academy of Sciences doi: 10.1073/pnas.1316402111.

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