Drinking Enough Water
Even in cool weather, you need two to four quarts of water a day. Under most conditions, humans can only last about three days without water.
Pure drinking water is rare, even in the most remote regions. Clear mountain streams often are contaminated by Giardia lamblia, a parasite that causes serious intestinal sickness in humans.
The best way to purify water is by boiling. Chemical purifiers such as iodide/iodine and filter systems can be used, but some may not be satisfactory. Never make survival problems worse by drinking unsafe water.