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Distillation is the process of removing salt from water. It is done by applying a heat source to the water to turn it to vapor, thereby purifying the water. Solar distillation uses the sun as the primary source of heat. It is a relatively old technology, with the first solar distillation sill put into service in 1872 in Chile.
During distillation, impure water is exposed to heat. The heat causes the water to turn to vapor. The water vapor condenses and turns back into liquid water. The condensed water is free of salt and other impurities.
A solar sill has a few basic parts. Typically, a cover sits over a basin containing a shallow pool of impure water. Nearby is a storage tank where the newly purified water is kept. Sometimes the solar distillation sill is a separate basin, while other times it is set in a ground pit.
A basin distiller is an independent unit. It is covered with an arched glass top. The bottom of the basin is usually black or a dark color, to draw the sun's heat. The impure water turns to vapor within the basin and collects on the glass cover. The condensed water runs off the sides of the glass top into a series of gutters and collects in a storage tank below.
Solar distillation is also possible in a ground pit. A conical hole is dug in the ground and a cup placed on the bottom of it. A plastic sheet is suspended over the cup, with the low point resting directly over the cup. A small rock in the center of the plastic generally weights it, and defines the low point. Larger rocks secure the plastic above the surface. Water collects on the plastic and runs into the cup.
The fact that the technology is low-tech and uses a free resource as the primary energy source makes it a good choice for impoverished countries, and in emergency situations where standard energy sources are not available. Areas of the United States that are prone to hurricanes, such as Florida, are likely to have water distillation areas set up in case of power outages, or contamination of the water supply. The ability to produce an effective solar distillation area is also considered a necessary skill for outdoor explorers. Campers and survivalists should know how to set up a makeshift basin to collect rainwater and distill it, and should carry the necessary supplies.
@everetra - You don’t need to be out in the woods to benefit from solar distillation. You can simply use it as an alternative to bottled water.
The problem with bottled water for many people (including myself) is that you never really know where it came from. It may say that it’s distilled but news exposes have unveiled that in fact a lot of it is from tap water.
If you distil your own water, you know the stuff is pure and it’s not hard to build a distiller. You just need a tilted glass like the article says, a basin where the impure water collects and another basin to collect the distilled water. As the water evaporates it will collect on the glass and slide down into the basin that collects pure water.
As a survival method out in the woods, I suppose that it would be useful indeed. However, you would need patience. It takes time for the water to evaporate, distill and condense into enough water to keep you alive.
I think you can go three days without water so you may have time to get the water you need from your makeshift solar water distiller. One thing you should definitely not do is drink water directly from a stream or a pond. I guarantee that you will get sick. You never know what kind of bacteria and even poisons may be floating around in there.