Cross Connection Practice Exam

Which type of valve configuration is typically used in a backflow prevention assembly to mitigate backpressure?

1. Single check valve

2. Double check valve

3. Pressure reducing valve

4. Pressure relief valve

The correct answer is: Double check valve

The double check valve configuration is specifically designed to mitigate backpressure, which occurs when the pressure in the downstream system exceeds that of the supply line, potentially causing contaminated water to flow back into the potable water supply. In a double check valve assembly, two independent check modules are used in tandem to provide a robust barrier against backflow. This redundancy is essential because if one valve fails, the second valve acts as an additional safeguard, significantly reducing the risk of any backflow occurring. The two check valves working together ensure that any backpressure created within the system does not lead to the reverse flow of water, thereby maintaining the integrity of the potable water supply. Other configurations, such as the single check valve or the pressure relief valve, do not offer the same level of protection against backpressure. A single check valve may not effectively prevent backflow on its own, especially in situations where pressure fluctuations are present. While a pressure relief valve serves a different purpose—typically related to managing pressure in a system rather than specifically preventing backflow—it does not address backpressure conditions in the same way that a double check valve does. The pressure-reducing valve is focused on reducing upstream pressure but also doesn't directly contribute to backflow prevention in the same context.