Which backflow device is acceptable to use when a system is supplied by more than one water source, with one potable and the other non-potable?

Which backflow device is acceptable to use when a system is supplied by more than one water source, with one potable and the other non-potable?

• A. Reduced Pressure Principle (RP)
• B. Atmospheric Vacuum Breaker
• C. Double Check
• D. Pressure Vacuum Breaker

Answer: (A)

When there are multiple water sources, including a non-potable one, you must protect the potable supply from both backflow types: back-siphonage and backpressure. The reduced pressure principle (RP) device provides the highest level of protection for these conditions. It uses two check valves with a relief valve between them, so if pressure on the supply side drops or a backflow attempt occurs, the relief valve vents to the atmosphere and prevents contaminated water from reaching the potable line. This robust protection is why an RP is the acceptable choice for a system fed by more than one source. Atmospheric vacuum breakers and pressure vacuum breakers only guard against back-siphonage; they don’t protect against backpressure, and they have installation and usage limitations that make them unsuitable when a non-potable source could backflow into the potable supply. A double-check valve offers some protection but is generally limited to lower-hazard cross-connections and isn’t considered adequate for a multi-source, non-potable scenario.

When there are multiple water sources, including a non-potable one, you must protect the potable supply from both backflow types: back-siphonage and backpressure. The reduced pressure principle (RP) device provides the highest level of protection for these conditions. It uses two check valves with a relief valve between them, so if pressure on the supply side drops or a backflow attempt occurs, the relief valve vents to the atmosphere and prevents contaminated water from reaching the potable line. This robust protection is why an RP is the acceptable choice for a system fed by more than one source.

Atmospheric vacuum breakers and pressure vacuum breakers only guard against back-siphonage; they don’t protect against backpressure, and they have installation and usage limitations that make them unsuitable when a non-potable source could backflow into the potable supply. A double-check valve offers some protection but is generally limited to lower-hazard cross-connections and isn’t considered adequate for a multi-source, non-potable scenario.