LESSON 4
PHYSICAL AND CHEMICAL TESTS AND STANDARDS
Section I. PHYSICAL AND CHEMICAL STANDARDS
4-1.
GENERAL
Although the sanitary quality of water (as measured by bacteriological analyses)
is usually the governing criterion as to the potabiIity of a water supply, the physical and
chemical characteristics must also be considered. A brief discussion of the physical
and chemical characteristics of water was included in paragraph 1-7. Some of these
characteristics merely alter the aesthetic qualities of the water by imparting an
unpleasant odor, taste, or appearance. Other impurities are actually harmful to the
consumer when present in excessive quantities. The STANAG 2136 and SOLOG
Agreement 125 establish physical and chemical, as well as bacteriological standards for
drinking water. In addition, the Environmental Protection Agency (EPA) has established
1975 interim standards that govern when in conflict with other standards.
4-2.
PHYSICAL CHARACTERISTICS
Turbidity, color, odor, and taste standards are easiIy attained by properly
designed and operated treatment plants and equipment. Supplies used without
treatment should also meet these requirements. Although these standards do not
directly relate to the safety of the water, they are closely related to consumer
acceptance. Experience has shown that many people turn to alternate supplies, which
may be less safe, when these characteristics exceed the following levels:
a. Turbidity--1 unit (EPA int std)
b. Color--15 units
c. Threshold odor number--3
d. Taste--Unobjectionable
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4-3.
CHEMICAL SUBSTANCES
a. Inorganic Chemicals--Primary Standards. Any substances in excess of
those concentrations Iisted in Table 4-1 constitute grounds for rejection of the water
supply
MD0160
4-2