You can’t deny this one. It’s a godsend in dry climates and in oceanic survival scenarios. String up a tarp to funnel the rain, or lay some plastic sheeting down in a hole to make a clean puddle, or set out your pots, pans and bottles under the open sky. The rain is ready to drink, as long as you catch it in a clean container and there’s nothing overhead to contaminate it (like a forest or jungle canopy peppered with bird droppings). If I don’t need every single drop I can catch under the trees, I will let the rain wash off the canopy for a while before I start collecting ready-to-drink water. And if every drop counts, I’ll start catching it right away and simply disinfect the water before consumption. Boil it, filter it, zap it with UV light, or add your most trusted chemical disinfectant – then you won’t have to worry about any parasites or pathogens that may have washed down from the treetops.