How well do we understand water use?

Another interesting study, again of Americans rather than Canadians, suggests that we have a fairly poor perception of where in our daily lives we use water. This could have important, and not very helpful, consequences for increasingly needed water conservation initiatives.

The study, by Professor Shahzeen Z. Attari of the School of Public and Environmental Affairs, Indiana University, is based on an online survey of 1020 Americans and shows that people underestimate water use by a factor of 2 on average, with large underestimates for high water-use activities. In addition, there is poor understanding of embodied water content in food products.

According to the paper, previous research estimated that 13.2 gallons of clean water are required per person per day for human needs (drinking, sanitation, hygiene, and food preparation). In 2005, the average American used about 98 gallons of water per day, of which about 70% was used indoors. An open ended question indicated that Americans view shorter or fewer showers, turning off water while doing other activities (not including brushing teeth), and turning off water while brushing teeth s by far the most effective water conservation measures. In fact, according to US Environmental Protection Agency, toilets use the most volume of water of household indoor activities and their suggested retrofit is the top recommendation made. However, “buying water-efficient appliances and fixtures” along with “water-efficient toilet” and “flushing less” are among the actions least-mentioned by study participants.

The study identifies several weaknesses such as small sample size and the lack of rigour of internet-based survey methodologies. Nevertheless, the research suggests that there is a lot of room for improved public education about water supply and use issues. GallonDaily finds it interesting that shower use comes out at the top of public perception of household water use. There has been much more publicity and advertising about shower use and low flow showerheads than there has about low-flush toilets and toilet water efficiency. Ngos, municipalities, and toilet manufacturers might do well to take note of these issues when planning education and marketing campaigns.

The paper is available at

For those interested in this type of research, the same researcher in 2010 published a similarly interesting study about public perceptions of energy efficiency opportunities. That study can be found at

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