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January 09, 2014
Survival Skills: How To Desalinate Water in the Field - 1
by Tim MacWelch
Last week, I received a call from some friends who provide survival training for a branch of the Department of Justice. They were mid-experiment, trying to desalinate water with field expedient gear. Short of building a still as featured on the show Moonshiners, they couldn’t figure out how to achieve the necessary controlled water condensation. Their results were hit and miss, as many of my experiments with this technique have been. I have built several pressure canner stills (for water, don’t get too excited!) and some tea kettle water distillers, but these large pieces gear aren’t going to fit in anybody’s backpack or survival kit.
Why use distillation for water? Radiation, lead, salt, heavy metals, and many other contaminants could taint your water supply after a disaster. If you try to simply filter them out, you will ruin your expensive water filter. In a scenario where the only water available is dangerous water, there aren’t many options. The safest solution is water distillation. Water can be heated into steam, and the steam can then be captured to create pure water, despite many forms of contamination—including radioactive fallout. Distillation won’t remove all possible contaminants, like volatile oils and certain organic compounds, but most heavy particles will stay behind.
For home-based disaster survival situations, a quick way to make a steam distiller is with a pressure canner and some small-diameter copper tubing. The best part about this operation (aside from the resulting safe water) is that the canner stays intact. This allows you to shift gears from water distillation to food preservation very easily (providing you are not dealing with radiation). The only tricky part is getting the copper line fitted to the steam vent on the canner’s lid. This is a cool setup, but how can you use materials that you’d typically have when bugging out or backpacking?
After some failed tests involving tin foil cones and other bizarre apparatus, I finally devised a system of three containers and a gutter piece. This top container needs to be metal and filled with ice, snow, or cold water. The second container sits over a bed of coals or simmering stove, and contains the salty water. A gutter piece (a foil strip in my tests) catches the drips from the underside of the top container, and channels the water into the third container. This is your drinking water.
The volume of water you produce will depend on the size of the containers and the coldness of the uppermost container. In my best test, I received 3 ounces of perfectly distilled water in one hour, rendered from one pint of salty water. Of course there’s plenty of room for improvement and modification, but this sure beats lugging around a still and a worm (condensation coil). For best results, follow these distillation tips.
Use wind screens, if needed, to keep your steam in the right place, which is underneath your top container of cold liquid.
Make sure your gutter stays in place. Use sticks, string, tape, or whatever you can find to keep this important water pathway in place.
Use the coldest stuff you have in the upper container, as steam condenses best on drastically cooler surfaces.
Be patient! This is improvised gear, and it will perform as such.
If you’re using salt water or contaminated water in the upper container, make sure it cannot spill down onto your gutter, which would add salt or contamination to your hard-earned fresh water.
Do you distill water at home? Or do you have a different method? Please let us know by leaving a comment.