CDPH Water Distribution Grade 2 Practice Test 2025 – Your All-in-One Guide to Exam Success!

The most effective order of protective methods for backflow prevention devices is indeed based on their ability to prevent contaminated water from entering the potable water supply, and the air gap stands as the best method due to its physical separation between two water systems. An air gap completely eliminates the possibility of backflow, as it creates a substantial distance between the water source and any potential contaminants.

Following the air gap, the Reduced Pressure Zone (RPZ) assembly is highly effective. It incorporates two independently acting check valves and a relief valve that allows for the safe release of any backflow that might occur, ensuring that any back pressure does not force contaminants back into the potable water system.

Next in effectiveness is the Double Check Valve Assembly (DCVA), which uses two check valves to prevent backflow. While it is reliable, it lacks the additional features that the RPZ possesses, which means it is slightly less effective in situations where contamination hazards are higher.

Lastly, a Vacuum Breaker (VB) provides a basic level of protection against back siphonage, but it is only effective under specific conditions and can fail if subjected to certain conditions, such as continuous flow or high pressure situations. This limitation places it at the end of the hierarchy of protective methods.

Understanding