In general, types of backflow prevention devices required are as follows:
A. A service connection to premises having an auxiliary water supply or internal system containing water of deteriorated quality shall be protected by an approved double-check valve assembly.
B. A service connection to premises handling dangerous or toxic materials such as industrial plants, hospitals, mortuaries, etc., shall be protected by an approved reduced pressure principle backflow prevention device properly located and installed.
C. A service connection to any sewage treatment plant or sewage pump station shall be protected by an air-gap separation to prevent backflow.
(Ord. 539 (part), 1988).