Check out this low-cost, highly-efficient, solar-powered water purifier called WaterCone! Make your own for your next outing in the desert, mountains, whereever.
You pour the bad water into a black pan, and then you screw on a cone. The black pan absorbs sunlight and heats up the water. Then, the evaporated water condensates into droplets on the cone’s inner wall, and the droplets drop into a circular trough at the inner case of the cone. After a few hours, you can unscrew the cap, tip the cone upside down and empty out the clean water into a receptacle.