During a commercial plumbing inspection, the inspector notes a direct connection between the potable water supply and a process tank containing a non-potable chemical solution. There is no air gap or backflow preventer. What type of backflow hazard is this, and what is the minimum required protection?

Question: During a commercial plumbing inspection, the inspector notes a direct connection between the potable water supply and a process tank containing a non-potable chemical solution. There is no air gap or backflow preventer. What type of backflow hazard is this, and what is the minimum required protection?

Answer options:

• Moderate hazard; Double check valve assembly ✅ Severe hazard; Reduced Pressure Principle (RP) assembly
• Low hazard; Atmospheric vacuum breaker
• Minor hazard; Pressure vacuum breaker

Correct answer: Severe hazard; Reduced Pressure Principle (RP) assembly

Explanation: A direct connection between potable water and a non-potable chemical solution constitutes a severe backflow hazard due to the potential for contamination of the drinking water supply with toxic substances. The National Plumbing Code of Canada (NPC) typically requires a Reduced Pressure Principle (RP) backflow prevention assembly for severe hazards because it provides the highest level of protection by incorporating a relief valve that opens to discharge water to atmosphere in cases of backpressure or backsiphonage.