During a routine maintenance check in a hospital, a plumber identifies a direct connection between the potable water supply and a non-potable cooling water system without an appropriate backflow preventer. Which type of backflow prevention device would be most suitable to protect the potable water supply in this high-risk cross-connection, according to CSA B64.10?

Question: During a routine maintenance check in a hospital, a plumber identifies a direct connection between the potable water supply and a non-potable cooling water system without an appropriate backflow preventer. Which type of backflow prevention device would be most suitable to protect the potable water supply in this high-risk cross-connection, according to CSA B64.10?

Answer options:

• Double check valve assembly (DCVA) ✅ Reduced pressure principle assembly (RP)
• Pressure vacuum breaker (PVB)
• Atmospheric vacuum breaker (AVB)

Correct answer: Reduced pressure principle assembly (RP)

Explanation: The Reduced Pressure Principle Assembly (RP) is the most suitable device for high-hazard cross-connections, such as between potable water and a non-potable cooling system, because it provides the highest level of protection against both backpressure and backsiphonage. A DCVA is for moderate hazard, while PVBs and AVBs are only for backsiphonage protection in low-hazard situations with no continuous pressure.