In a setup with two water sources, one potable and one non-potable, which backflow protection device is acceptable?

In a setup with two water sources, one potable and one non-potable, which backflow protection device is acceptable?

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

Answer: (C)

When a potable water system could be connected to a non-potable source, you need a backflow preventer that blocks any flow back into the clean supply under all conditions, including both back-siphonage and backpressure. The reduced pressure principle backflow preventer does that with a robust design: two check valves in series and a relief valve between them. If the pressure on the potable side drops or the non-potable side pushes back, the relief port vents to drain and the check valves close, preventing any contamination from reaching the potable supply. This level of protection is why it’s required for cross-connections involving a non-potable source. Atmospheric or pressure vacuum breakers only guard against backsiphonage and rely on atmospheric venting; they don’t protect against backpressure and have installation and usage limits, so they aren’t suitable for a system with two water sources where backflow could occur. A double-check valve offers some protection but isn’t sufficient for high-hazard cross-connections like a potable/non-potable connection in many codes. The reduced pressure device provides the strongest, code-recognized protection for this scenario.

When a potable water system could be connected to a non-potable source, you need a backflow preventer that blocks any flow back into the clean supply under all conditions, including both back-siphonage and backpressure. The reduced pressure principle backflow preventer does that with a robust design: two check valves in series and a relief valve between them. If the pressure on the potable side drops or the non-potable side pushes back, the relief port vents to drain and the check valves close, preventing any contamination from reaching the potable supply. This level of protection is why it’s required for cross-connections involving a non-potable source.

Atmospheric or pressure vacuum breakers only guard against backsiphonage and rely on atmospheric venting; they don’t protect against backpressure and have installation and usage limits, so they aren’t suitable for a system with two water sources where backflow could occur. A double-check valve offers some protection but isn’t sufficient for high-hazard cross-connections like a potable/non-potable connection in many codes. The reduced pressure device provides the strongest, code-recognized protection for this scenario.