(1) A cross-connection on a public water supply system must be eliminated by the disconnection of the cross-connection whenever reasonably practicable.   Whenever elimination of a cross-connection is not reasonably practicable and the cross-connection creates a health or water contamination hazard, the hazard must be eliminated by the insertion into the piping of an approved backflow prevention assembly or device in accordance with (2) of this rule.

(2) For the cross-connections identified below, the following types of approved backflow prevention assemblies or devices must be used:

(a) A health hazard created by a cross-connection that may be subject to back pressure must be eliminated by an approved reduced pressure zone backflow prevention assembly or an air-gap.

(b) A health hazard created by a cross-connection that may be subject to back siphonage, but not subject to back pressure, must be eliminated by an approved air-gap, pressure vacuum breaker assembly, atmospheric vacuum breaker, or a reduced pressure zone backflow prevention assembly.

(c) A water pollution hazard created by a cross-connection that may be subject to back pressure must be eliminated, at a minimum, by an approved double check valve assembly.   The cross-connection condition described in this subsection may also be eliminated by an air-gap or by an approved reduced pressure zone backflow prevention assembly.

(d) A water pollution hazard created by a cross-connection that may be subject to back siphonage, but is not subject to back pressure, must be eliminated, at a minimum, by an approved double check valve assembly, pressure vacuum breaker assembly, or an atmospheric vacuum breaker device.   This cross-connection condition described in this sub-section may also be eliminated by an air-gap or by an approved reduced pressure zone backflow prevention assembly.

(3) A backflow prevention assembly or device must be installed and maintained, at a minimum, in accordance with the manufacturer's specifications.

(4) This rule applies to piping between water systems outside of any building and to piping within any building, including cross-connections in plumbing systems.

(5) The department may not approve a plan for the construction of a public water supply system containing provisions for cross-connection unless provisions for the protection of the public water supply are demonstrated in the plan.