That's what German industrial designer Imke Hoehler came up with for her Bachelor Thesis: catch fog to turn into drinking water. She designed these 'DropNets'. The nets capture tiny water droplets out of fog clouds, and unite the small droplets into bigger ones. You can receive up to 20 liters of drinking water a day with these bad boys. All you need for them to work is fog (and a lack of clean drinking water?). Nice execution of a (seemingly) simple idea! Check out the pictures at Imke's portfolio.