Where are check valve components typically located in a system that uses a check valve?

• A. In the mainline only
• B. Built into the sprinkler
• C. Under each sprinkler as separate valve
• D. In the controller cabinet

Answer: (B)

A check valve’s job is to stop water from flowing backward when a zone is turned off, preventing drainage from the lateral lines and keeping the zone primed. Placing the check valve built into each sprinkler head achieves this exactly where it matters: at the point of discharge. With the valve integrated into the head, each sprinkler independently resists backflow and water loss as soon as pressure changes, which is especially helpful on slopes or long runs where drainage would waste water and create soggy patches.

While inline valves in the mainline or separate valves under each sprinkler can be used in some designs, the common practice for ensuring immediate, local backflow prevention is to have the check valve built into the sprinkler itself. The controller cabinet is not a location that affects drainage or backflow; it only houses the control electronics.