Where there's a still, there's a way

Where there's a still, there's a way

Extracting water from the desert with a solar still

By Christopher Nyerges 02/26/2009

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Water, water everywhere, or so it seems. But sometimes in summer, in the dry deserts, the water that’s so critical to life can be hard to come by. Yet as Aborigines and Native Americans and desert explorers have learned, there are various ways to find water when there appears to be none.

Dew can be collected in the early morning by taking a clean cloth, and wiping off the surfaces of rocks or leaves and then squeezing the water into your canteen or mouth. Cactus pads can be singed of their spines, peeled, and the interior can be chewed for the water. No, this is not water you can fill your canteen with, and it is a bit slimy, but it will keep you alive.

On a recent wilderness training field trip in the nearby Big Tujunga Wash, students learned another relatively modern method for obtaining water from the desert called the solar still.

Here’s how student Denise Williams describes the process.

“While foraging, camping, or just surviving, you can collect water by digging a hole several feet deep and several feet wide. You place a receptacle in the bottom-center of the hole and surround that receptacle with leaves from local trees and forage. Then you completely cover this hole with a piece of plastic, placing large stones and sand around the outer top edges to secure the plastic from slipping into the hole. Water, evaporating from the vegetation and then gradually condensing, collects on the bottom side of the plastic and finally drips into the receptacle. For this process to be totally effective, you must place small stones onto the upper top center of your plastic to cause a downward indent so that the water droplets drip right into this receptacle.”

Of course, the key to success is to dig your hole where there is the greatest likelihood of underground water. Such places might be at the base of hills, or in dry stream beds. Location is very important.

Also needed is some digging implement, since without a shovel the only digging you can do is in the sand. Clear plastic is best for this and a cup or receptacle of some sort is needed. We took a discarded water bottle, cut off the top and used the bottom for the cup. We also placed grass and willow leaves around the receptacle, so we could also capture their evaporating moisture.

Our class spent about 30 minutes preparing the site and setting up the still. We returned about three hours later to find about a half-cup of distilled water.

According to Denise, “This was an awakening experience to learn how to capture water if none was available. I had often wondered what techniques to employ that could be easily understood and effective to stave off dehydration. What an eye-opening experience.”

Chris Haynes adds, “One of the most important lessons of my wilderness survival class was learning how to acquire water by constructing a solar still. I think that this method is a great example of ‘where there’s a will, there’s a way.’ Although this water still is very simple to make, it taught me that with a little insight and a lot of common sense ideas like this can be developed.”
Indeed! Another method we tried that day was the transpiration bag, a clear plastic (not black) bag, as large as possible, wrapped securely around the leafy end of a willow tree. It’s imperative that only non-toxic bushes and trees be used. When we came back after three hours, the transpiration bag had about as much water as the solar still, and it required hardly any labor. The water, however, had a very strong taste from the willow. We concluded it was wise to always plan ahead for any contingency, and that the transpiration bag would be a better, quicker choice — assuming we had the clear plastic bag with us.

There are many other ways to extract water from the desert, but more on that later.

Christopher Nyerges is the editor of Wilderness Way magazine, the author of “How to Survive Anywhere,” and an occasional blogger of current events. He can be contacted via this paper or at ChristopherNyerges.com.

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Comments

Generally, you'll sweat more water out of your body while building a still than you will recover from the still. Case in point: The whole class works for half an hour, and three hours later they have 1/2 cup of water. One half cup every three hours isn't going to do much for a class, and the still will not necessarily keep producing at that rate; the vegetation placed inside will dry out.

Even if you could recover more water from the still than you exuded while making the still, the amount of water recovered will typically not be sufficient for your survival needs (depending on the season and climate).

The transpiration bag mentioned later in the article is a better option, particularly if you can set up several of them. However, you do need to carry around large, clear plastic bags with you, which most people don't.

The real survival technique? Make sure you either carry enough water with you or plan your trips around reliable water sources. Most water procurement methods* won't do much for you.

HJ

*The exception being the water procurement devices on life boats. When you're in the ocean, you have plenty of water; you just have to render it potable.

posted by hikin_jim on 3/11/09 @ 04:05 p.m.
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