For which type of plumbing connections is a double check valve typically used?

A double check valve is primarily used for low hazard plumbing connections. In these situations, the risk of contamination from backflow is minimal. The double check valve serves as a protective measure to prevent any possible backflow that could introduce pollutants into the potable water supply. It consists of two check valves assembled together, providing an added layer of protection that is appropriate for scenarios where the potential for backflow is recognized but does not include significant health risks.

In contrast, for high hazard connections, more robust backflow prevention methods, such as reduced pressure zone (RPZ) valves, are required. High hazard situations involve a greater risk of severe contamination, necessitating stronger protection measures than what a double check valve provides. Medium and no hazard situations similarly would not require the more stringent measures associated with high hazard backflow prevention, but they also might not be adequately protected with just a double check valve, depending on the specific conditions and guidelines outlined in the plumbing code.