Anti-Siphon Valve Placement for Drip Irrigation on Sloped Sites

For a drip system where the water source is 3 feet lower than the highest tubing (over 100 ft run), the anti-siphon valve must be installed at least 6 inches above the highest emission point in the system—not just at the source or the highest ground elevation.

Why This Matters

Anti-siphon valves (ASV) prevent back-siphonage by venting air when pressure drops. If any outlet (dripper) is higher than the ASV's vent, siphonage can still occur. Code typically requires the ASV to be 12 inches above the highest head/outlet.

Practical Options

• If the highest dripper is only slightly above the source, mount the ASV on a post or wall at the required height.
• If the elevation difference is large, consider a pressure vacuum breaker (PVB) or reduced pressure principle assembly (RP) instead—they don't have the same height restriction but must be installed per local code.

Critical: Codes vary by jurisdiction. Contact a local Rain Bird dealer or irrigation supplier (not a big-box store) for the exact requirement in your area. They know the local amendment and can recommend the right device.