A solar still is a simple way of distilling water, using the heat of the Sun to drive evaporation from humid soil, and ambient air to cool a condenser film. Two basic types of solar stills are box and pit stills.
In a solar still, impure water is contained outside the collector, where it is evaporated by sunlight shining through clear plastic. The pure water vapor condenses on the cool inside plastic surface and drips down from the weighted low point, where it is collected and removed. The box type is more sophisticated. The basic principles of solar water distillation are simple, yet effective, as distillation replicates the way nature makes rain. The sun's energy heats water to the point of evaporation. As the water evaporates, water vapor rises, condensing on the glass surface for collection. This process removes impurities, such as salts and heavy metals, and eliminates microbiological organisms. The end result is water cleaner than the purest rainwater.
Approximately 8 square feet (of cover) will distill around 1 gallon of water per day, over five hours of full sunlight. The most important elements of the design are the sealing of the base with black, high temperature silicone rubber and creating a good seal between the glass cover and the bottom of the box.
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Box Still 
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Pit Still 
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