Backflow Prevention Practice Exam

Which scenario increases the risk of backsiphonage?

1. Increased demand for water

2. Decrease in upstream pressure

3. Water temperature increase

4. Use of a filter

The correct answer is: Decrease in upstream pressure

The scenario that increases the risk of backsiphonage is a decrease in upstream pressure. Backsiphonage occurs when there is a negative pressure in the distribution system, which can cause the flow of water to reverse direction. This typically happens when there is a sudden drop in pressure, often due to events such as fire hydrants being opened, a burst water main, or excessive water usage. When the pressure drops significantly, it can create a vacuum effect that pulls contaminated water from a source (like a nearby pond or chemical storage area) back into the potable water supply, posing significant health risks. In contrast, increased demand for water does not directly cause backsiphonage; it may lead to lower pressure but not necessarily to a condition that creates a vacuum. Similarly, an increase in water temperature does not inherently affect pressure dynamics in a way that would promote backsiphonage. The use of a filter typically serves to improve water quality and does not contribute to the conditions for backsiphonage.