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 or chlorine and filter systems can be used, but some may not be satisfactory. Never make survival problems worse by drinking unsafe water.
Solar stills can provide emergency drinking water. Ground water condenses on a plastic cone set in the ground and drips into a collecting pan.
To make a solar still:
- Dig a pit 3 feet wide by 18 inches deep.
- Place a shallow container in the center.
- Run a tube from the container to the edge of the pit.
- Lay clear plastic over the pit and place a rock or a little soil in the center to form a cone.
- Draw water through the tube to avoid disturbing the still.
- Make several stills if you have no other source of water.