Cross Connection Practice Exam

Which type of valve prevents backflow during drinking water usage?

1. Check valve

2. Relief valve

3. Pressure reducing valve

4. Isolation valve

The correct answer is: Check valve

The check valve is designed specifically to allow fluid to flow in only one direction and prevent backflow in a system. This function is critical in drinking water systems to ensure that contaminated or stagnant water does not flow back into the clean water supply, which could pose serious health risks. The construction of a check valve includes a movable disc or flap that opens when water flows in the desired direction and closes to block reverse flow. In contrast, a relief valve is typically used to release excess pressure in a system, a pressure reducing valve regulates the pressure to prevent system overload, and an isolation valve allows for the maintenance of a section of the pipeline without shutting down the entire system. While these types of valves serve important functions, they do not specifically prevent backflow like a check valve does.