What is the primary function of a check valve in an irrigation sprinkler system?

• A. Allow water to flow in both directions
• B. Allow water to flow in one direction
• C. Regulate pressure in the line
• D. Filter debris from the water

Answer: (B)

At its core, a check valve is there to stop water from flowing backward in the line. In an irrigation system, forward flow moves water to zones, but when pressure changes or a zone valve closes, water in the downstream piping could be drawn back toward the supply. The check valve opens for normal forward flow and automatically seals when reverse flow would occur, keeping the water moving in one direction only. This prevents backflow and potential contamination of the water supply, and it helps maintain the intended isolation of zones.

It’s not a regulator, so it doesn’t set or limit pressure, and it’s not a filter, so it doesn’t remove debris. Those functions belong to separate devices.