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Should we recycle urine on Earth, too?

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(Read caption) The Three Gorges Dam in Yichang, Hubei province, China has completed trial water storage operations. According to the World Health Organization, some 1.1 billion people lack access to clean water.

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After five days of tinkering, astronauts aboard the International Space Station ran their first successful test Tuesday of equipment that turns urine into drinking water.

Delivered to the station by the Space Shuttle Endeavour, the $154 million water recycling system, which also processes sweat and moisture from the air, is designed to quench astronauts' thirst while requiring fewer costly resupply missions. Samples of the recycled water will be tested back on earth before astronauts aboard the station can start drinking from the system's tap.

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This raises a question: Can we build these things on earth? Maybe even for a little less than $154 million?

A thirsty planet

There's definitely a need. According to the World Health Organization, some 1.1 billion people lack access to clean water. That's almost 1 in 6 human beings. And according to the United Nations Development Programme, women and girls in developing countries collectively spend more than 10 million "person-years" hauling water from remote sources each year.

And it's only getting worse. As a study published in Nature in April predicts that, by 2025 more than half of the world's countries will face freshwater stress or shortages, and by 2050, as much as 75 percent of the world's population could face freshwater scarcity.

A cheap and reliable urine-to-potable-water device could solve what is arguably the world's No. 1 problem, so to speak.

It wouldn't be the first time that NASA's water-purification technology spins off into the developing world. In 2006, engineers from the space agency helped develop a system for the northern Iraqi village of Kendala, which filters and purifies water from nearby streams, wells, and swamps.

H20 is H20

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If you think about it, enjoying a refreshing glass of erstwhile whiz is not as disgusting as it sounds. What is "new" water anyway? As NASA astronaut Sandra H. Magnus told the New York Times after pointing out that water flushed down our toilets eventually evaporates and rains down into our reservoirs. "We drink recycled water every day — on a little bit longer time scale."

The concept of treating our bodily waste as a useful product is probably alien to most of us, but it hasn't always been that way. In ancient Rome, human urine was put to work tanning leather and whitening togas. The stuff was so valuable that the 1st-century emperor Vespasian imposed a tax on it.

Is it technically possible?

Aside from revulsion, a major obstacle to widespread urine recycling is the energy needed. You can distill it, but that requires bringing it to a boil. If you're the outdoors type, you may know how to construct a solar still – which uses a plastic sheet to create a sort of greenhouse effect to evaporate ground water and condense it into a cup.

The Watercone, a simple solar still designed to purify sea water, holds great promise as an inexpensive solution. But its maker remains silent on whether the award-winning device would work with urine.

Inventor Dean Kamen has no such reservations. The mind behind the Segway scooter appeared on the Colbert Report in March, claiming that his energy-sipping Slingshot vapor compression distiller could produce 1,000 liters of water a day out of any wet substance, including the ocean, a puddle, a chemical waste site, or "a 50-gallon drum of urine."

But how does it taste?

The New York Times's John Schwartz had the opportunity to sample NASA's recycled water at the Kennedy Space Center. The verdict: "Not bad, actually," although he noted that it tasted faintly of iodine, which was added to the water near the end of the process.

If these systems become widespread, we'll need a way to rid our recycled-urine water of that iodine flavor. Camping shops often sell little vitamin C tablets along with their iodine purification crystals to cut the harsh taste. But you can save your money on those overpriced tablets by dropping in a pinch of a substance that, even after NASA perfects its recycling system, will continue to hold pride of place in the space program: Tang.