US Army mountaineering techniques (basic)

You should never assume that mountain water is safe for consumption. You must drink
water only from approved sources. In order for you to operate efficiently, fluids lost
through respiration, perspiration, and urination must be replaced.
In mountain operations, hyperventilation and the cool, dry atmosphere bring about
a three-to-four-fold increase in water loss by evaporation through the lungs. You
must make an effort to drink liquids even when you do not feel thirsty. You
should drink one quart of water, or the equivalent, every four hours. If your unit is
conducting rigorous physical activities, you should drink more water.
You should drink at least four quarts of water each day. A loss of two quarts of
body fluid (2.5 percent of body weight) decreases physical efficiency by 25
percent. A loss of 12 quarts (15 percent of body weight) is usually fatal. In your
meals you should replace the salt lost by sweating to avoid deficiency and
cramping. Salt tablets are not necessary and may contribute to dehydration. Your
military rations (three meals a day) provide sufficient sodium replacement.
Drink small amounts of water often, a large volume may slow you down. If you
are hot, and the water is cold, severe cramping may result. Keep pure water in
reserve for first aid use. You must place emphasis on the three rules of water
discipline.
Drink only treated water.
Conserve water for drinking. Potable water in the mountains may be in
short supply.
Do not contaminate or pollute water sources.
Other sources of water are snow, mountain streams, springs, rain, and lakes. You
must make sure the water has been purified, no matter how clear it appears. After
the water has been purified, you may add fruits, juices, and powdered beverages to
supplement and encourage water intake. If the water supply is insufficient, reduce
your physical activities. Any temporary deficiency must be replaced to maintain
maximum performance.
All water that is to be consumed must be potable. Make sure that you drink water
only from approved sources or purify it to avoid contamination and disease. Do
not drink nonpotable water. Water that is unfit to drink, but is not dangerous, may
be used for bathing. You must avoid wasting water. To stay cool and maintain a
functioning body it is best to drink water as often as possible.
Since water is scarce above the timberline, watering parties should be established.
Snow and ice may be available for melting after sundown. You may dig a shallow