QUARTS OF WATER PER MAN PER DAY
Moderate Conditions* Severe Conditions**
or route marches with
heavy loads or in CBR
* Moderate Conditions = below 105F in desert and below 85F in tropics.
** Severe Conditions = above 105F in desert and above 85F in tropics.
Table 5-1. Guide to average drinking water requirements.
(2) Color. The true color of water is usually caused by organic substances
such as decaying vegetation. For this reason, water taken from swampy sources is
often highly colored. True color must be distinguished from the apparent color caused
by turbidity. Color is undesirable largely because of appearance. The presence of such
impurities as iron may also be detected by the color.
(3) Odor and taste. The tastes and odors found in water are caused by
algae (minute water plants), decomposing organic matter, dissolved gases, industrial
wastes, or certain mineral substances. The presence of bone oil and fish oil is
especially undesirable. Tastes and odors are more prevalent in surface water than in
ground water; cold water has less taste and odor than warm water. The odors are
usually described as aromatic, disagreeable, fishy, moldy, sweetish, and vegetable.
The strength of the odor varies from very faint to very strong.
(4) pH value. Impurities in water fall into two general groups, acidic
(vinegary) and alkaline (like lye). As water may contain both acidic and alkaline
materials, it is necessary to know the quantity of each because these impurities may
seriously affect such purification processes as coagulation and sedimentation and may
cause corrosive action. The pH value is a measure of the strength of acidity or alkalinity
expressed as a number ranging from zero for maximum acidity to 14 for maximum
alkalinity. It is measured on a scale (figure 5-1) with 14 divisions. A pH value of seven
indicates a neutral water, which means that whatever acid and alkaline substances are
dissolved in water are equal in strength. If acid substances predominate, the pH value
would be less than seven. A pH greater than seven indicates that the water is alkaline.
Neutral water is seldom found in nature and is not necessary. A pH value of seven is
not an indication that the water is pure. The pH value may be determined by a color