counter-clockwise from bottom left Saltwater is poured into the Watercone’s dish; the heat of the sun causes the water to condense; the desalinated water collects in the lip of the cone and is ready for drinking. All photographs Stephan Augustin

At last, some good news about the greenhouse effect: It’s the secret to Stephan Augustin’s Watercone, an elegant low-tech water-purifying condenser. The design is a simple clear polycarbonate cone, 23 to 31 inches (60 to 80 cm) in diameter, that rests on a black polycarbonate pan. The shapes are stackable for efficient shipping all over the world. It works by filling the pan with seawater and leaving it in the sun; the air’s natural heat-trapping gases cause the water to evaporate. The water beads up on the inside of the cone, and runs into the channel around its bottom edge. By flipping the cone upside down and unscrewing the cap, a person can collect up to one to 1.8 quarts (1.7 L) of safe, desalinated water a day. That’s enough to meet a child’s daily needs; two Watercones will take care of one adult.