Safety / Survival / Army Field Manuals / AFM 3-05.70
13-29. The subject of man and water in the desert has generated considerable
interest and confusion since the early days of World War II when the U.S. Army
was preparing to fight in North Africa. At one time, the U.S. Army thought it
could condition men to do with less water by progressively reducing their water
supplies during training. They called it water discipline. It caused hundreds of
13-30. A key factor in desert survival is understanding the relationship
between physical activity, air temperature, and water consumption. The body
requires a certain amount of water for a certain level of activity at a certain
temperature. For example, a person performing hard work in the sun at 43 degrees
C (109 degrees F) requires 19 liters (5 gallons) of water daily. Lack of the
required amount of water causes a rapid decline in an individual's ability to
make decisions and to perform tasks efficiently.
13-31. Your body's normal temperature is 36.9 degrees C (98.6 degrees F).
Your body gets rid of excess heat (cools off) by sweating. The warmer your body
becomes—whether caused by work, exercise, or air temperature—the more you
sweat. The more you sweat, the more moisture you lose. Sweating is the principal
cause of water loss. If you stop sweating during periods of high air temperature
and heavy work or exercise, you will quickly develop heat stroke. This is an
emergency that requires immediate medical attention.
13-32. Figure 13-2 shows daily water requirements for
various levels of work. Understanding how the air temperature and your physical
activity affect your water requirements allows you to take measures to get the
most from your water supply. These measures are—
Find shade! Get out of the sun!
Place something between you and the hot ground.
Limit your movements!
Conserve your sweat. Wear your complete uniform to include T-shirt. Roll
the sleeves down, cover your head, and protect your neck with a scarf or
similar item. These steps will protect your body from hot-blowing winds and
the direct rays of the sun. Your clothing will absorb your sweat, keeping it
against your skin so that you gain its full cooling effect. By staying in
the shade quietly, fully clothed, not talking, keeping your mouth closed,
and breathing through your nose, your water requirement for survival drops
If water is scarce, do not eat. Food requires water for digestion;
therefore, eating food will use water that you need for cooling.
Figure 13-2. Daily Water Requirements for Three Levels of
13-33. Thirst is not a reliable guide for your need for water. A person who
uses thirst as a guide will drink only two-thirds of his daily water
requirement. To prevent this "voluntary" dehydration, use the
At temperatures below 38 degrees C (100 degrees F), drink 0.5 liter of
water every hour.
At temperatures above 38 degrees C (100 degrees F), drink 1 liter of
water every hour.
13-34. Drinking water at regular intervals helps your body remain cool and
decreases sweating. Even when your water supply is low, sipping water constantly
will keep your body cooler and reduce water loss through sweating. Conserve your
fluids by reducing activity during the heat of day. Do not ration your
water! If you try to ration water, you stand a good chance of becoming a heat