In facilities using a contaminated auxiliary water supply for fire protection, what is required for the potable water service connection?

In facilities that utilize a contaminated auxiliary water supply for fire protection, the connection to the potable water service needs to be safeguarded to prevent any potential backflow contamination. The use of a Reduced Pressure Zone (RPZ) assembly is specifically designed for this purpose.

An RPZ consists of two check valves with a pressure differential relief valve located between them. This configuration not only prevents the backflow of contaminated water into the potable system but also maintains a constant pressure difference, which allows for automatic relief of any backpressure or backsiphonage conditions that might occur. This is essential in scenarios where there is a risk of contamination from an auxiliary water supply, as the RPZ effectively mitigates the dangers associated with varying pressure conditions, ensuring that potable water remains uncontaminated.

The other options, while they may provide some level of protection, do not offer the comprehensive safety features of an RPZ in the context of backflow prevention where contaminated water supplies are involved. For example, an atmospheric vacuum breaker operates effectively in preventing back siphonage but not under continuous pressure conditions, and a double check valve may not provide sufficient protection against backpressure. Therefore, the use of a Reduced Pressure Zone assembly is the only option that meets the stringent requirements for protecting potable