UN experts concerned by water footprint
By Arthur Max, Associated Press
DELFT, Netherlands — It's not only our carbon footprint we should worry about, U.N. experts say. They warn about our growing water footprint.

Nearly half the people on Earth, about 2.5 billion, have no access to sanitation, many of them in urban slums. The world's cities are growing by 1 million people a week, and soon their aging water systems will not cope. Farming demand on water is increasing.

"What we are doing now can't keep up with the issues we already have," said Carol A. Howe, an expert working for a UNESCO-led water development project called Switch.

"Something needs to change. It needs to change quickly, and it needs to be fairly dramatic," she told a symposium for journalists Wednesday.

The threat of climate change has drawn attention to the carbon footprint, the amount of greenhouse gases produced by human activity. Now scientists have begun calculating a water footprint, the amount of water needed to produce goods or services.

A report published this month by UNESCO's Institute for Water Education in Delft said it takes 70 to 400 times as much water to create energy from biofuels as it does from fossil fuels.

It said 262 gallons of water is needed to produce crude oil that provides the same amount of energy from biomass grown in Brazil — primarily sugar cane used for ethanol — that requires 15,972 gallons of water. Biomass grown in the Netherlands needs 6,284 gallons, the report said.

Engineers are experimenting in a dozen cities from Lima, Peru, to Beijing to find ways to ease the pressure on water resources.

The projects, run by the U.N. Education, Scientific and Cultural Organization and funded by the European Union, include turning rooftops into gardens, capturing and recycling rain, recharging underground reservoirs with waste water, and swapping traditional flush sanitation for dry toilets.

Birmingham, England, is monitoring the effects of green roofs on reducing flooding during storms, cutting energy needs and capturing run-off to reduce water needs in buildings and surrounding areas, Howe said.

A project in Tel Aviv, Israel, channels treated waste water into an aquifer through the natural filtering system of the soil, and is testing whether it can be reused for drinking water, she said.

Waterless toilets, using either chemicals or composting, are being tested in Ghana, Kenya, Peru, Egypt and elsewhere. They also enhance the possibility of separating human waste, using liquid waste as a rich source of nutrients for crops, said Gary Amy, a professor of urban water supply and sanitation with the institute.

"If we captured all the urine in Africa, it could match all the nitrogen and phosphates used for agriculture," he said.

Howe said standard mechanisms consume about 25% of all residential water — drinking water that is literally flushed down the toilet.

"It takes a lot of energy and money to bring in the water, to treat it, to put into the toilet, to treat it again, and to put it into the river system," she said.

Original article: USA Today
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