The solar still is a simple invention that collects and distills water through a greenhouse effect. It’s not perfect, nor does it collect massive quantities of water, but it does provide fresh water in arid climates and saltwater environs.
It was invented by Dr. Ray Jackson and Dr. Cornelius Van Bavel of the U.S. Department of Agriculture in the 1970s. In their original method, a square of clear or milky plastic 5×5 or 6×6 is draped over a 3-feet-deep hole with a clean cup or other container in the bottom.
The plastic is encircled with a rim of dirt to seal off the still, and weighted down in the middle with a small rock or similar weight. The rock is pushed down to create a 45-degree cone. A rubber or vinyl drinking tube can be placed in the cup so that water can be sipped as it collects, without having to take the whole still apart to get the cup of water out.
Build the still in a sunny location and in the dampest dirt or sand around. Green vegetation and cacti can be added to the hole to increase water production. Just remember that this thing is not a water fountain. The most I ever got in one day was 2 ounces.
The water is as clean as the surfaces it has touched and may not need purification. However, I have had plenty of dirt particles roll down the inside of the still and into the cup. One time, I even had a dead fly in the cup of water inside the still (I have no idea how he got in there).
In desert conditions, even urine can be recycled by peeing down a hole dug next to the still so the liquid can soak through the ground and vaporize in the still pit.
This is not a fun project if you have to dig in dry or rocky soils, especially if you have no shovel. But this contraption is a winner in moist, sandy soils and it does desalinate water. Think about adding the plastic and vinyl hose to your lifeboat survival kit–the still works great at the beach if you could protect it from the wind.
Let us know if you’ve made a solar still, and how it worked.