Backflow Prevention Practice Exam

What type of device can be used to prevent backsiphonage?

1. Air gap

2. Check valve

3. Pressure regulator

4. Flow meter

The correct answer is: Air gap

An air gap is a highly effective device used to prevent backsiphonage. It is a physical separation between the source of water supply and a potential contamination source. By maintaining this gap, the drinking water is effectively protected from contamination that could occur if there is a reversal of flow caused by negative pressure in the system, also known as backsiphonage. This device works simply yet effectively, as it relies on gravity to ensure that no backflow can occur. For example, if a faucet is submerged in a pot filled with dirty water, if there is a drop in water pressure in the municipal supply, the dirty water could be drawn back into the clean water system without an air gap. The air gap creates a barrier, making it impossible for the contaminated water to enter the potable supply. While check valves are designed to prevent backflow under certain conditions, they are not foolproof against backsiphonage as they can fail if there is a significant drop in pressure. Pressure regulators help maintain a consistent pressure in a plumbing system but do not prevent backsiphonage. Flow meters measure the flow of water but do not serve any function in preventing contamination. Therefore, the air gap is the most effective method for preventing backsiphonage,