RV Tank Fittings

Connecting tanks, valves, and hoses

Fittings are where an RV waste system either seals up clean or drips at every joint. Most are ABS and go together with a bayonet twist-lock, a slip joint, or ABS cement, and the trick is matching the connection type and diameter on both sides. A clear fitting at the dump end is worth having — it's the only way to see when the water finally runs clear.

• Elbows and adapters. A clear 45-degree elbow like the Valterra Clearview or a 90-degree unit like the Camco Rhino Sewer Adapter PRO connects your hose to the ground inlet and threads into a 3-to-4-inch NPT cleanout. The drain-lock ring seals it into the inlet so it doesn't blow back out.
• Wyes and ell fittings. A flanged wye or 2-way ell like the Valterra units combines or splits outlets — handy when you're plumbing two tanks to one hose or adding a second connection point. Rotating flanges let you aim the outlet where you need it.
• Flush and fill fittings. A tank flush fitting (the Icon 2" slip) adds a rinse port to a holding tank, and a fill kit like the Valterra RK907 barbed elbow ties a fresh or gray line into the tank with cement.
• Connection type and size. Bayonet, slip, spigot, hub, and NPT thread don't mix — check what's on your valve and hose before ordering, and confirm the diameter (2" vs. 3") matches.

When you replace a fitting, it's the moment to check the gate valve flange it bolts to and the sewer hose end it mates with — a new adapter against a worn seal still leaks. If you're plumbing a new holding tank, buy the fittings fresh rather than reusing brittle ones.