String + Bottle + Lighter = Drinkable Water
Sure, it's not the best-tasting water you'll ever have but - if you're lost, dehydrated and have an empty bottle handy - it'll do in a pinch. All you'll need are the above instruments and a puddle of water: get some water, start a small fire and hold the bottle over the flame to bring it to a boil. Once that's done, let it cool and take a swig of perfectly drinkable water (a nice variant, and more accurate/user-friendly version, of a tip we highlighted several weeks ago). Thanks Keith Hanshaw!