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Rain Bird Anti-Siphon Valve Leaks at Cap Assembly

Persistent Leak from Anti-Siphon Valve Cap After Cleaning and Diaphragm Replacement

A 1-year-old Rain Bird ¾″ anti-siphon valve leaks continuously at the cap. Cleaning the gasket, tightening the cap, and replacing the diaphragm didn't help.

Anti-Siphon Valve Leak Points

Cap gasket: The gasket sealing the cap to the body.
Poppet/plunger: Inside the cap, a plunger seats against the top of the cap when water flows. If deformed or stuck, it leaks.
Over-tightening: Can distort the cap or gasket. Hand-tighten only.

Recommended Fix

Replace the entire anti-siphon assembly with a brass unit (e.g., Champion brand, under $15). Brass units are more durable and less prone to leakage. If the Rain Bird valve is returnable, do so.

Irrigation: Hardie 2" Valve Solenoid Replacement: Irritrol Parts Compatibility; Troubleshooting a “Possessed” Zone Valve That Runs With Every Station; Why a Weather-Matic Sprinkler System Blows Fuses; Rain Bird 600: Manual Mode Zone 2 Opens Zone 1 Instead; Sprinklers Weak Until Bleed Valve Opened – Bad Diaphragm; Rain Jet RU711 3/4" Valve Leaks Through Cap—Diaphragm Access; Rain Jet Anti-Siphon Valve Leaks: Replace Valve Top or Internal Plunger; Main Anti-Siphon Leaking: Redundant with Valve Anti-Siphons?; Valves 2 & 4 Low Pressure: Replace Diaphragms, Verify Orientation; How Underground Sprinkler Valve Boxes Stay Securely in Place

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