What type of backflow prevention device is not recommended as protection in situations where a health hazard may result from failure?

• A. Double Check Valve
• B. Reduced Pressure Zone device
• C. Air Gap
• D. Pressure Vacuum Breaker

Answer: (A)

When a health hazard could result from backflow, you need the strongest protection to prevent any contaminated water from entering the potable supply. A double check valve relies on two check valves to block reverse flow but has no venting or relief mechanism to address backpressure events. If a check valve leaks or debris prevents a tight seal, backflow can still occur and contaminate the system. In contrast, devices designed for health-hazard protection include an air gap, which physically separates the supply from potential contamination, and a reduced pressure zone (RPZ) device, which has a relief valve to vent and prevent backflow under both backpressure and backsiphonage. A pressure vacuum breaker protects against backsiphonage but is not suitable for health hazards in many codes. So the double check valve isn’t appropriate for situations where a health hazard could result from failure.