Feature |  Science/environment

Every drop counts: Saving water while washing dishes, brushing teeth

By Zhang Qian  |   2009-11-10  |     NEWSPAPER EDITION


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For many people, washing hands under running tap is nothing but common, unware of the water and energy it has wasted. Actually for some personal hygiene, the tap should not run constantly and water can be collected for later use.

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AFTER dinner, Jessica Wang collects the dishes as usual, scrapes off leftovers and puts the dishes in the sink. She rinses them under running water, one by one.

The 28-year-old says most of her friends wash dishes this way and she thinks it's common in cities. Rinsing under running water is necessary to get rid of detergent residue, which is bad for health, she says.

Wang washes fast and says running the tap doesn't waste much water since she works quickly. Upon finishing, she washes her hands, still letting the tap run.

But that method wastes a lot of water and energy and doesn't get dishes that clean. A recent study finds that this hand method uses 10 times more water than a standard automatic dish washer.

It also uses about the same amount of electricity (about 2kw to heat water) as that used to run a standard washer.

The survey, headed by Rainer Stamminger, professor of household and appliance technology at the Institute of Agricultural Engineering of Bonn University, covered 230 people in 13 countries across continents, including 30 people in China.

The result shows that each Chinese participant used an average of 109 liters of water to wash 140 items - sixth highest among 13 countries. Russians used the most, 163 liters, while Germans used the least, 54 liters.

"Though many Chinese rinse dishes under running tap water as they think that will clean better, the results don't bear that out," says Stamminger. "Washing under running tap water actually consumes high amounts of resources."

Running the tap during washing is a huge waste and it is not rare among urban families.

Many housewives also persist in rinsing fruits, vegetables and clothes under running tap, as they believe that only this way can they get rid of all chemical residue.

"Washing dishes, fruits and clothes under running water makes them cleaner. Isn't that common sense?" says Jiang Laidi, 58, a retired housewife. Asked about wasting water, she shrugs. "It's okay, as long as the result is clean. This kind of waste, I think, is worthwhile."

There's more waste: Many people keep the tap on while they shower, wash their hands and face and brush their teeth. They say it's pointless to turn the tap on and off for short periods, like tooth brushing.

If they wash quickly there won't be much waste, they believe.

"But if you collect the running water, instead of sending it down the drain, you will be surprised at how much you have used," says Stamminger.

In the survey, the water that the Chinese used in washing 140 dishes amounted to 55 two-liter bottles. Obviously, people wash far fewer items at one time, but the waste principle is the same.

Nowadays, given concerns about H1N1 flu, frequent hand washing is very important and some running water is necessary, but washing still can be done more efficiently and the tap doesn't have to run all the time.

As for bathing and other personal hygiene, the tap should not run constantly and water can be collected for later use.

Chen Zhen, a 56-year-old retiree in Zhabei District, is an expert in this. She collects and reuses dish water for multiple tasks, including mopping the floor and flushing the toilet. Last year she was Shanghai's No. 1 Energy-Saving Hero.

Chen's family of four adults saved four tons of water and 320 kwh over three months, March, April and May, of last year.

Her family also ranked No. 2 in China in the family energy-saving competition sponsored by the World Wildlife Fund, Beijing Global Village and Shanghai Xuhui District Environmental Protection Bureau.

Chen's secret of water-saving is collecting the not-so-dirty water in plastic basins. She collects water from the last wash of vegetables, dishes, hands and the bath.

"You don't need 100 percent clean water for everything," says Chen, "and you don't produce 100 percent dirty water in every chore. Pouring not-so-dirty water down the drain is a big waste."


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