A plumber is connecting a chemical dispenser to a potable water supply line in a commercial kitchen. The chemical solution is toxic and could be drawn into the potable water system if a pressure drop occurs. Which backflow prevention device provides the highest level of protection against severe health hazards in this situation?

Question: A plumber is connecting a chemical dispenser to a potable water supply line in a commercial kitchen. The chemical solution is toxic and could be drawn into the potable water system if a pressure drop occurs. Which backflow prevention device provides the highest level of protection against severe health hazards in this situation?

Answer options:

• Air gap
• Double check valve assembly (DCVA) ✅ Reduced pressure principle assembly (RPBA)
• Pressure vacuum breaker (PVB)

Correct answer: Reduced pressure principle assembly (RPBA)

Explanation: For connections involving toxic chemicals or severe health hazards, the Reduced Pressure Principle Assembly (RPBA) provides the highest level of backflow protection. It features two independent check valves with an automatically operating differential pressure relief valve located between them, discharging to atmosphere when pressure is unbalanced, thereby preventing backflow under both backpressure and backsiphonage conditions. An air gap is also highly protective but may not be practical for a direct connection, while DCVAs and PVBs are not suitable for severe health hazards.