How I Transformed Sewage Into Fresh Water

02-18-2014 • http://www.popsci.com, By Chris Hackett

Say the apocalypse happens tomorrow. The good news: You survive! No more credit card debt or miserable commutes. The bad news? Infrastructure has collapsed and there’s no clean drinking water. Most people can’t last a few days without it, so what we need is a reliable way to purify some from toxic soup.

Distillation covers nearly all bases, freeing H2O of salts, pollutants, microbes, viruses, and other nasties. A common method is moonshine-style, using sealed pots, fire, and complex plumbing. Or it can be done more safely and lazily by harnessing the sun.

Solar stills elegantly miniaturize the cycle that draws water from oceans and lakes, stores it in clouds, and returns it to Earth as rain. I made the one below using caulk and tools from my workshop, plus a windshield, wooden pallets, duct tape, and simple plumbing I salvaged from a nearby Dumpster.

Suspect water goes into a shallow box; the sun shines through the windshield and evaporates the water—leaving behind a stew of contaminants. When the vapor hits the cooler windshield, it condenses back into liquid, trickles into a gutter, and drips into a bucket.