Jabsco 1-1/2-Inch Anti-Siphon Vented Loop Fitting

The Jabsco 1-1/2-Inch Anti-Siphon Vented Loop (part 29015-0010) is the larger of the two Jabsco loops, sized for 1-1/2-inch sanitation hose, a common size for toilet discharge lines. When a toilet bowl sits at or below the waterline, a hose full of seawater can start siphoning and keep running long after you stop pumping. A vented loop placed above the waterline lets air into the top of the hose run and breaks that siphon.

The fitting does nothing if it is mounted too low, so the high point of the loop has to stay above the waterline even when the boat heels or is loaded down. Jabsco installation sheets call for the loop to sit well above the static waterline, and sailboats usually need extra height to cover heel. On a sailboat, mounting it near the centerline helps keep it high on either tack.

The small vent on top can clog with salt crystals or waste residue, which quietly turns the loop back into a plain elbow. Check it each season by blowing gently through the valve or soaking it in warm fresh water, and replace it if it stays blocked. Use proper sanitation hose and double hose clamps where the hose meets the barbs. The 1-inch loop and more plumbing parts are in our marine toilets and sanitation systems.

• Fits 1-1/2-inch sanitation hose
• Part 29015-0010
• Breaks siphon on below-waterline toilets
• Vent should be checked every season