12VAC5-635-210: Backflow prevention

A. A rainwater harvesting system shall be designed, installed, and maintained to prevent contamination of secondary water supplies by backflow. Backflow prevention shall be achieved by one or more of the following:

1. Backflow elimination methods, including air gap separation or physical disconnection;

2. Backflow prevention assemblies, including the reduced pressure principle, double check valve, and pressure vacuum breaker assemblies; or

3. If backflow prevention is not generally required to withstand continuous pressure over 12 hours or to control high hazards, a backflow prevention device, including atmospheric type vacuum breakers and dual check valve devices.

B. Backflow prevention assemblies and backflow prevention devices shall be suitable to the application and shall conform to the USBC.