Which type of backflow prevention assembly is required to protect the potable water supply when chemicals are introduced into a lawn irrigation system?

• A. Atmospheric vacuum breaker
• B. Reduced pressure principle backflow prevention assembly
• C. Dual check valve assembly
• D. Pressure vacuum breaker

Answer: (B)

The correct choice, which is a reduced pressure principle backflow prevention assembly, is essential for protecting the potable water supply in situations where there is a potential for contaminants, such as chemicals, to enter the drinking water system. This type of assembly is designed to prevent backflow and is particularly effective in applications where hazardous substances are introduced into the water system, as is common in expanded use of lawn irrigation systems that might involve fertilizers or pesticides.

A reduced pressure principle assembly contains two independently acting check valves and a pressure differential relief valve located between them. This design ensures that even if there is a drop in pressure in the potable water supply, the potential for backflow of these contaminants is mitigated, thereby safeguarding the drinking water supply.

In contrast, other options might not provide adequate protection. For instance, an atmospheric vacuum breaker, while useful for preventing back siphonage, does not provide protection against backpressure scenarios. A dual check valve assembly offers limited protection and may not be sufficient where potentially harmful chemicals are introduced. A pressure vacuum breaker, while more effective than an atmospheric vacuum breaker, still does not offer the same level of protection as a reduced pressure principle assembly, especially regarding toxic substances.

In summary, the reduced pressure principle backflow prevention assembly is