(c) Nor more than 5 percent of the samples may have 3 or more
portions positive when 20 or more samples are collected per month.
3-15. STANDARDS FOR SWIMMING POOLS AND NATURAL BATHING AREAS
a. Samples. Samples should be collected at least twice weekly at both the
deep and shallow end and should include periods of heaviest swimming.
b. Coliform Densities.
(1) Swimming pools. In order for swimming pool water to be acceptable, not
more than 15 percent of the membrane filters may show more than 1.0 coliform colony
per 50 ml. If the multiple-tube technique is used, not more than 15 percent of the
samples may show positive (confirmed) tests for coliform organisms in any of the five
10-ml portions of a sample.
(2) Natural bathing areas. Since the sanitary quality of natural bathing
waters cannot be controlled, it is not feasible to set an acceptable standard according to
coliform density. Instead, natural bathing waters are classified according to their
acceptability as shown in Tables 3-1 and 3-2. The decision whether or not to use a
natural bathing area is made by the commanding officer based upon the
recommendations of the appropriate surgeon.
ml, or No. of
of sample filtered 1
Preferred, but not generally attainable
inland streams free to fresh sewage
Undesirable unless complete sanitary
May be dangerous if caused by fresh
No swimming unless complete survey
When the membrane-filter technique is used.
Table 3-1. Classification of inland (fresh) waters.