Backflow Prevention Practice Exam

A backflow preventer should be installed above what level?

1. Ground level

2. Water source level

3. Atmospheric level

4. Above the highest fixture

The correct answer is: Above the highest fixture

Installing a backflow preventer above the highest fixture is essential to ensure proper functioning and prevent backflow into the water supply. This placement creates a physical barrier that helps protect the potable water supply from contamination or pollution due to backflow events. By situating the backflow preventer higher than the highest fixture, it ensures that any potential backflow can be adequately regulated and doesn’t compromise the water supply. This method takes into consideration the principle of preventing backpressure and backsiphonage, where water that is typically under pressure can flow back into the clean water system due to a drop in pressure or a negative pressure situation elsewhere in the system. If the backflow preventer is placed below the highest fixture, then there may not be sufficient height to prevent waste or contaminated water from entering the potable system during such events. Hence, installation above the highest fixture is a critical aspect of backflow prevention design standards and regulations.