From Ready Nutrition:
This is Part II of a pair of articles on finding and obtaining water in the field. The last one we covered some methods of chemical purification, and stressed (as we stress here): boiling is the safest method to purify your water. Keep in mind something I didn’t mention in the previous article: water that is contaminated by pollutants such as toxic chemicals and industrial wastes is not able to be purified by chemicals or boiling to make it safe for drinking. We will address that in a minute.
How to Distill Water
We covered some basics, and along with that is how to find surface water that is relatively uncontaminated. This is where the boiling came in, to remove the pathogens (as many as possible) safely. Now, what do you do when you come across a water source that has a chemical sheen and an odor about it? You can remove the water by condensation. If you can’t filter it through a Brita or other system that removes chemical contaminants, take a small pot, and (preferably) a glass lid that is larger than the opening of the pot. You’ll need a third vessel. This is for “pour off,” of your condensed water.
Straining off as much as you can (with a piece of cloth, and perhaps an empty plastic bottle, pour some water into the smaller pot. Then bring it to a boil, and set the glass lid over it, and tilt it at an angle to one side (45 degrees is fine). The bottom tilted edge of the lid needs to be able to “empty” into a clean vessel. When you boil the water, the steam that condenses on the bottom of the lid is water: you can collect this and use this to drink, effectively removing enough contaminants to make the condensed water potable.
You’ll have to improvise to either hang the lid at an angle with some weight on one edge to make the tilt possible, or build a stand. Just make sure the lid doesn’t touch the top edge of the pot with the water to be condensed. Don’t boil it all the way down! Leave about an inch of water or so to enable you to get rid of the newly-concentrated chemical “slurry” now remaining in the pot.
Next, a solar still. There are plenty of diagrams available for this one. Dig a hole, conically-shaped about 2-3’ in depth, and line around that hole, covering it with clear plastic, a 9’ square sheet is best. You then place a collecting receptacle underneath the center of the plastic. Line the edges of the sheet with stones, and place a small stone in the center of the plastic sheet. It is best to cut green, non-poisonous vegetation and line your hole with it before you cover it with the plastic sheet. The collecting vessel should be at least a quart, because in this method, you will obtain 1 quart of water per…