3 August 1998
4-4. ENVIRONMENTAL CONSIDERATION. For information on environmental policies,
objectives, and guidelines refer to AR 200-1, for Army Projects and AFR's 19-1 and 19-2 for
Air Force Projects.
4-5. WATER QUALITY CONSIDERATIONS. Guidelines for determining the adequacy of a
potential raw water supply for producing an acceptable finished water supply with conventional
treatment practices are given in paragraph A-2 of TM 5-813-3/AFM 88-10, Vol. 3.
a. Hardness. The hardness of water supplies is classified as shown in table 4-1.
Table 4-1. Water Hardness Classification.
mg/L as CaCO3
Very Soft to Soft
Soft to Moderately Hard
Hard to Very Hard
Softening is generally considered when the hardness exceeds about 200 to 250 mg/L. While
hardness can be reduced by softening treatment, this may significantly increase the sodium
content of the water, where zeolite softening is employed, as well as the cost of treatment.
b. Total dissolved solids (TDS). In addition to hardness, the quality of ground water may
be judged on the basis of dissolved mineral solids. In general, dissolved solids should not
exceed 500 mg/L, with 1,000 mg/L as the approximate upper limit.
c. Chloride and sulfate. Sulfate and chloride cannot be removed by conventional
treatment processes and their presence in concentrations greater than about 250 mg/L
reduces the value of the supply for domestic and industrial use and may justify its rejection if
development of an alternative source of better quality is feasible. Saline water conversion
systems, such as electrodialysis or reverse osmosis, are required for removal of excessive
chloride or sulfate and also certain other dissolved substances, including sodium and nitrate.
d. Other constituents. The presence of certain toxic heavy metals, fluoride, pesticides,
and radioactivity in concentrations exceeding U.S. Environmental Protection Agency
standards, as interpreted by the Surgeon General of the Army/ Air Force, will make rejection of
the supply mandatory unless unusually sophisticated treatment is provided. (For detailed
discussion of EPA water standards, see 40 CFR 141, AR 420-46 and TB MED 229 for Army
Projects and AFR 161-44 for Air Force Projects.)