As droughts make water more scarce, every drop counts. Hundreds of millions of people around the world lack easy access to safe drinking water. And water scarcity is expected to worsen as droughts become more extreme. “With climate change, water is just becoming a bigger issue,� says Robert Foster, chairman of the American Solar Energy Society. He says one small-scale solution is to use the sun to purify any water that is available, such as contaminated well water. It’s an age-old technique called solar distillation. The sun heats up water in a glass-covered basin. The water evaporates, leaving salt and impurities behind. That pure water vapor condenses on the glass and runs down to a trough where it can be collected. Foster says most stills produce only a couple of gallons of drinking water each day, but they can help people who have few other options. Foster has helped equip families along the U.S.-Mexico border with solar stills to purify well water polluted with arsenic and fluoride. And he’s worked with Pacific Islanders who use stills to turn saltwater into fresh, drinkable water. “So it’s a great opportunity for people to clean their water who might not otherwise have an easy way to do it,� he says. “You don’t need electricity … you just need sunlight.� Reporting credit: Sarah Kennedy/ChavoBart Digital Media DIY Solar Still There are many solar stills available online but in an emergency, you can build your own solar still with some plastic sheeting and a collection cup, and a bit of sweat equity. Dig a pit into the ground Place a bowl at the bottom of the pit that will be used to catch the condensed water Cover the pit loosely with plastic sheeting using stone or other heavy object to hold it in place over the pit. Be sure that the lowest part of the plastic sheet hovers directly over the bowl. Leave your water “trap� in the sun by day, or overnight and collect water from the bowl in the morning. Credit: Daniele Pugliesi Source: usgs.gov/media/images/how-build-your-own-solar-still