As the developing world struggles to find ways to tackle the scarcity of usable water, most people in the United States are unaware of how to conserve water and have only a vague idea of how much water is used for different activities.
According to a national online survey conducted by an Indiana University researcher, nearly 43 percent people cited taking shorter showers - which does save water but may not be the most effective action.
Very few participants cited replacing toilets or flushing less, even though toilets use the most volume of water daily.
Experts say the best strategy for conserving water is to focus on efficiency improvements such as replacing toilets and retrofitting washing machines.
"People may be focusing on curtailment or cutting back rather than efficiency improvements because of the upfront costs involved," said Shahzeen Attari, an assistant professor at Indiana University Bloomington's school of public and environmental affairs.
"It is also surprising how few participants mentioned retrofitting their toilets. Even though toilets use less water volumetrically than washers and showers per use, the frequency of use results in the highest water use overall," she explained.
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The survey asked 1,020 participants to estimate water used by 17 different activities such as using a carwash, taking a shower for 10 minutes, using a standard flush and so on.
Results show that on an average, participants underestimate water use by a factor of two, with severe underestimates for activities that use a lot of water.
Finally, and not surprisingly, participants had no clue about how much water was needed to produce four particular foods: rice, coffee, sugar and cheese.
According to Attari, "Given that we would need to adapt to more uncertain fresh water supplies, we need to find ways to correct misperceptions to help people adapt to temporary or long-term decreases in freshwater supply," Attari added.
The paper appeared in the journal Proceedings of the National Academy of Sciences.