A water still is a way to extract water from the soil. The principle is similar to that of a still a moonshiner would make in the woods, but it’s much simpler.
The simplest water still is powered by the sun and nature’s water cycle. However, before we get started, keep in mind that this still, known as a “solar still,” is a method of last resort. Although I’ve made many to learn how to do it and see how it works, I’ve never had to make one in a situation for which it would be life or death to have water.
This is a survival technology that might enable you to get some water when none is apparently available. It’s possible that you’d need to know how to do this if you were lost in the desert or if you were marooned on some remote beach with only sea water. It can also be useful in other environments.
First, let’s look at how to make the still. Then, after you see how to make it and how it works, we’re going to explore other ways you might obtain water that are a lot easier and perhaps more reliable than the solar still.
• One large, clear plastic sheet (ideally at least 6x6 feet)
• A cup or container
• A shovel
It only takes about 30 minutes to dig and set up a solar still, and it can be left there indefinitely.
Location is very important. You should dig in a place where the most water is likely to be found not far below the surface. That means you’re going to dig in a dry stream bed, not up high on a hillside. If you’re at the beach, you’ll dig in the sand above the high-tide line.
In an ideal location, you’re going to dig a hole about 3 feet deep and 3 feet wide. A shovel obviously makes this easier, but I’ve done it with hubcaps and sticks. The type of soil you’re digging in will determine the kind of tool you’ll need.
Place your container in the middle of the hole. You can also place green vegetation (non-toxic) around the container, because the vegetation will also give up some of its water.
Next, cover the hole with the sheet of plastic, and seal the edges of the plastic with the soil you just dug out. Place a stone in the middle of the plastic so that it’s situated directly above the container. It should be just heavy enough to cause the plastic to sag in the middle. That’s it.
Now, you wait.
If conditions are just right (they rarely are), and if there’s water underground, water will continue to evaporate out of the soil, as it always does as part of the hydrological cycle. Your plastic sheet will trap the moisture that comes out of the hole. It will condense on the underside of the plastic and drip back down into the container ... again, that’s if everything goes right (check out the accompanying pictures, because this is a pretty simple procedure).
How much water can you obtain in your container? In several situations in desert conditions, I had mixed results. After about 24 hours, I have gotten no water (in some cases), a couple of tablespoons and, in a few cases, nearly a quart. The amount you get is highly variable, but it depends largely on the season and the amount of water that’s underground where you dug.
On one occasion when I built a solar still in the mountains, there was heavy dew that night. Nearly a quart of water collected on top of the plastic sheet, but only a few tablespoons had been collected in the inside container.
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