Made of porous woven flax, most desert water bags hold from 1 to 2 quarts, depending on size. Because of the extremely low humidity in a desert environment, these bags make good use of evaporation to keep their life-sustaining contents surprisingly cool and drinkable.
These bags generally have a shoulder strap for carrying, and a plastic or aluminum cap at one of the top corners.
Although these bags are prized by soldiers and Marines working in desert operations, they are not suitable for use in a biological or chemical warfare environment due to their porosity and lack of gas-mask drinking tube attachment. In these cases, standard military-issue canteens should be used.
If you have ever spent a good amount of time working outdoors in a desert environment, you'll appreciate the fact that keeping your drinking water in a regular canteen allows it to reach ambient temperature, which could be well over 100 degrees F.