(A) The type of protection required under § 51.073(A) and (B) of this chapter shall depend on the degree of hazard that exists, as follows.
(1) An approved air gap separation or an approved reduced pressure principle backflow prevention device shall be installed where a public water supply system may be contaminated with any substance that could cause a system hazard or health hazard.
(2) An approved double check valve assembly shall be installed where a public water supply system may be contaminated with any substance that could cause a pollution hazard.
(3) An approved reduced pressure principle backflow prevention device shall be installed at the service connection where a plumbing hazard exists.
(4) In the case of any premises where, because of security requirements or other prohibitions, it is impossible or impractical to make a complete cross-connection survey of the consumer’s potable water system, a reduced pressure principle backflow prevention device shall be installed at the service connection.
(B) An approved anti-siphon vacuum breaker may be used as a backflow prevention device where it is not subjected to back pressures. This device shall not be used for applications where water flow is expected to be continuous for 12 or more hours. The device shall be installed ahead of the potential source of contamination on the discharge side of the last control valve. It shall be placed, at the least, 18 inches above the highest point reached by any water passing through the potential source of contamination. Typically, this type of device is used for such equipment as lawn sprinklers, water-cooled compressors or other water-cooled equipment.
(Prior Code, § 6-129)