Figure 6-15. Reduced pressure backflow preventer.
6-13. SUMMARY
The environmental health specialist is not expected to be a sanitary engineer, nor
a plumber. He cannot be expected, therefore, to detect improperly functioning backflow
preventive devices. However, he should understand the principles of backsiphonage
caused by cross connections. The majority of cross connection hazards are indirect
cross connections caused by carelessness or ignorance of the principles of
backsiphonage. In conducting inspections of water distribution systems and other
faciIities, the environmental health specialist should be constantly on the alert for
situations in which the principle of the positive air gap has been inadvertently or
intentionally defeated. Such situations must be brought to the attention of the
responsible individuals. In situations where it is not possible to provide a positive
vertical air gap and it appears that no provision has been made for a backflow-
preventing device, the fact should be made known to the sanitary engineer or the
environmental science officer for further investigation by technically qualified personnel.
Section III. GENERAL TREATMENT IN THE EVENT OF CONTAMINATION
6-14. GENERAL
Primary emphasis in the protection of water supplies must always be placed on
prevention of contamination. Nevertheless, because of the numerous hazards involved,
contamination of water supplies is a factor with which we must always be prepared to
deal. The medical departments of the Army and the Air Force have established a
logical set of procedures to be followed when water samples from a potable water
system are found to be contaminated. These measures, outlined in paragraphs 6-15
through 6-17 below, are not intended as substitutes for individual initiative and judgment
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