What is the purpose of a backflow preventer in an irrigation system?

• A. To filter sediment from water before it reaches plants
• B. To increase water pressure in the mainline
• C. To stop irrigation timing from running during rain
• D. To prevent irrigation water from contaminating the potable water supply by blocking reverse flow.

Answer: (C)

Backflow prevention focuses on protecting the drinking water supply from contamination that could be drawn back through the irrigation system. If pressure in the main water line drops or a component fails, irrigation water can flow backward into the potable supply. A backflow preventer blocks that reverse flow, creating a barrier so potentially contaminated irrigation water can’t enter taps, wells, or the public water system. This protects health and safety by preventing fertilizers, pesticides, soil, and other contaminants from backward-flowing into drinking water.

This device isn’t about filtering sediment (that’s a filter), nor about increasing pressure (that’s a regulator or pump), nor about stopping irrigation during rain (that’s a rain sensor or controller feature).