What is one of the key features of a double check valve assembly?

A double check valve assembly is designed to prevent backflow, particularly from non-potable sources into potable water systems. This feature is crucial in protecting the drinking water supply from contamination. The assembly consists of two independent check valves installed in series, allowing it to effectively isolate and prevent any reversal of flow that could introduce harmful substances from non-potable systems.

In applications where there is potential for contamination, the double check valve assembly serves as an important safeguard by ensuring any backflow is halted before it can compromise the clean water supply. It is typically utilized in situations where the health hazard is considered moderate, which makes its functionality critical.

While the other options mention features like air gap separation or pressure maintenance, these do not accurately describe the direct purpose and application of a double check valve assembly in preventing backflow specifically from non-potable sources. Therefore, the emphasis on its role in safeguarding potable water against non-potable contaminants highlights its key functional attribute.