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An Extra Cheap Way To Get Salt Out Of Water Could Help Make The World Less Thirsty

Desalination is usually a hugely expensive and environmentally costly process, but this simple clay still just needs a little sunlight to render brackish water clean and delicious.

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Finding clean water can be a matter of life and death. Globally 3.4 million people die each year due to a lack of clean water, roughly the population of Los Angeles. For about one-tenth of the world’s population, at least 880 million people, a reliable supply of clean water remains decades away.

But a clever design by Gabriele Diamanti is bringing clean drinking water—in a small way—much closer. Called "Eliodomestico," the solar still uses clay pottery, a metal basin, and sunlight to power a water desalination process that can work in the developing world. Because for a big chunk of those 880 million people, there is water nearby, it just happens to be undrinkably full of salt.

A solar still works on the same principles bootleggers used to make moonshine during Prohibition: evaporate a liquid with heat and then collect the condensation (and what’s left over). During hot days, Eliodomestico uses the Sun’s energy to evaporate un-purified water into vapor that condenses into water on the relatively cool interior surfaces of the pottery. This fresh, purified water runs into a basin below and is removed to be carried home. Salt and other contaminants are left behind.

At the moment, transforming salt and brackish water into fresh water is often expensive and energy intensive: power plants and hundreds of millions of dollars are needed to run larger desalination plants.

The Eliodomestico, on the other hand, is carried by hand and costs about $50. While the open-source design (anyone can use the schematics to build it locally) puts out just five liters per day under favorable conditions, Diamanti says the design is half the price of and 60% more productive than existing models.

For those without clean water to drink, that promises to be a much needed relief. Diamanti says he is now planning further development to run chemical tests on the water, offer the schematics to African craftsmen, and test local production and marketing of Eliodomestico.

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