Cross Connection Practice Exam

What situation can lead to backsiphonage?

1. Increased system pressure

2. Sudden drop in water pressure

3. Excessive flow demand

4. Daily usage fluctuations

The correct answer is: Sudden drop in water pressure

Backsiphonage occurs when there is a sudden drop in water pressure within a potable water system, creating a vacuum that can pull contaminants from non-potable sources into the drinking water supply. This condition often arises due to events such as a broken water main, a fire hydrant being opened, or a significant increase in water usage in a particular area that causes the pressure to drop unexpectedly. When the pressure drops, it can create a negative pressure gradient, allowing water from other sources to flow backward into the main water supply. This backward flow can carry pollutants from sources such as irrigation systems, industrial processes, or sewage systems, compromising the safety of the drinking water. In contrast, increased system pressure, excessive flow demand, and daily usage fluctuations typically do not create conditions conducive to backsiphonage. Increased pressure would actually push water away from potential contaminants, while excessive flow demand usually leads to a drop in pressure but more gradually and in a controlled manner, which may not generate the extreme conditions necessary for backsiphonage. Daily usage fluctuations are common in water systems and do not cause the immediate and significant pressure drop needed to trigger backsiphonage.