TonGass (2 x Combo Pack, Black) RV Sewer Pipe Adapter, 3" Rotating Rigid Bayonet Adapter with Male Thread & Hooks, Termination Fitting with 3" Bayonet & Hub, RV Sewer Hose Connector for Waste Disposal

First impressions

Outfitting an RV waste system is all about small pieces that prevent big messes. The TonGass RV sewer adapter combo aims to cover two of the most common connection points with a matching pair of black ABS fittings: a rotating twist-on outlet adapter with bayonet hooks and a termination adapter with a standard 3-inch slip hub. Both are built around 3-inch RV standards, and both are meant to be solvent-welded into a rigid run of pipe. Out of the box, the parts feel stout and the bayonet features are well formed. The rotating collar moves freely without feeling sloppy, which matters when you’re trying to line up a connection at arm’s length.

I used the combo to build a semi-permanent hookup at home and tested it at a campground pedestal. One adapter went onto a short 3-inch ABS riser for my rig’s outlet; the other terminated a section of pipe that interfaces with a standard sewer hose or cap. The goal was a cleaner, repeatable connection with fewer flex points and less twisting.

What’s in the combo and what it fits

• Rotating twist-on outlet adapter: 3-inch “twist-on” bayonet with four hooks and a 3-inch female slip hub. The rotation lets you clock the hooks to your outlet without fighting the pipe run.
• Termination adapter: 3-inch bayonet/lug interface and a 3-inch female slip hub for solvent welding to pipe. It acts as the final connection point for a hose or cap, or ties into 3-inch threaded plumbing via the appropriate DWV adapter.

Both pieces are ABS and sized for 3-inch DWV. The slip hubs are sized to accept 3-inch ABS or PVC pipe (outer diameter about 3.5 inches). If you’re mixing materials, use the right cement: ABS cement for ABS-to-ABS, and a transition cement for ABS-to-PVC. Do not use PVC primer on ABS.

Build quality and design

The black ABS walls are thick enough to inspire confidence without adding bulk. The bayonet hooks on the rotating adapter have crisp edges and a consistent profile, which helps them lock fully without chewing up the mating lugs. The lugs on the termination adapter are equally well defined and mate cleanly with common RV hose couplers. The rotating collar has just the right drag—easy to turn by hand, but not so loose that it free-spins once aligned.

I checked the slip hubs for roundness and ID consistency with a caliper; both were true enough for a uniform solvent joint. Mold lines were present but minimal. Keep in mind that ABS, especially in black, can soften in direct sun; store these out of prolonged heat when you can, and don’t leave sustained mechanical stress on a fresh glue joint.

Installation notes

I dry-fit everything first. The slip hubs seated fully on schedule 40 ABS with a clean, square cut. For the ABS-to-ABS joints, I used fresh, medium-bodied ABS cement and followed standard prep: deburr, wipe clean, solvent-weld with a 1/4-turn twist, hold for 30 seconds. Where I tied into a run of PVC, I used an ABS-to-PVC transition cement and allowed a longer cure. If you plan to connect to a 3-inch threaded plumbing line, you’ll need an appropriate DWV male adapter on the pipe side—wrap with PTFE tape and use a non-hardening thread sealant rated for plastics.

The rotating adapter’s collar let me align the bayonet hooks after the glue set, which is the biggest ergonomic win here. On tight installs, that rotation avoids the “almost there” misalignment that can plague fixed fittings.

In use: sealing and handling

Sealing performance comes down to two things: geometry and gaskets. Geometry here is correct—standard 3-inch bayonet spacing and depth—so the weak link is usually the gasket in your hose or cap. On my first hookup, I saw a slow drip at the bayonet interface when I cracked the black tank valve. Reseating the hose’s O-ring and applying a dab of silicone plumber’s grease solved it. The hooks needed a firm twist to reach full engagement; once there, the connection stayed put during the dump, with no play.

The termination adapter’s lugs accepted multiple hose brands I tried, and the locking tabs landed positively. I also appreciated having a rigid end to push against. When you’re managing a heavy hose with full tanks, a rigid, square termination prevents the hose from wriggling the connection loose.

The rotating adapter on the rig’s outlet made it easier to connect without torquing the pipe. Because it rotates independently, I didn’t have to fight the hose’s tendency to twist as I locked it on. That reduces stress on both the bayonet face and the glued joint.

Durability and maintenance

ABS is hardened enough for RV duty but doesn’t love impacts in the cold. Treat the fittings like you would any rigid plumbing: protect from kicks, avoid overtightening clamps around the slip hubs, and give solvent joints a full cure before load. I left the assembly pressurized only during dumps and stowed the hose afterward; that’s a good habit to minimize long-term stress.

A few practical maintenance tips that paid off:
- Inspect and lubricate bayonet gaskets with silicone grease; replace flattened O-rings.
- Keep the bayonet faces clean; grit acts like sandpaper on seals.
- If a connection weeps, check that the hooks reached full lock—back off and re-engage until you feel the stop.
- Don’t use petroleum-based lubricants on rubber seals.

After several cycles, the hooks showed no rounding and the rotating collar remained smooth. The black finish scuffs like any ABS but that’s purely cosmetic.

Compatibility considerations

These adapters follow the common 3-inch RV standard. They worked with every standard bayonet hose and cap I had on hand. If your existing equipment is out of spec or heavily worn, you may need to refresh gaskets or add a secondary flat gasket to get a perfect seal. Threaded connections on the plumbing side require you to supply the correct DWV adapters; nothing exotic, but it’s worth planning your parts list before you start.

One practical note: the slip hubs are forgiving, but a slightly ovalized pipe end can cause a poor solvent joint. Square your cuts and use a proper deburring tool instead of a utility knife. If a hub or pipe looks out of round, don’t force it—heat can relax ABS gently, but it’s better to start with true components.

Ergonomics and day-to-day value

The rotating feature is the hero here. It saves you from “twist fighting,” especially when clearance is tight under the rig. Having both a rotating outlet and a proper termination adapter in one pack lets you standardize your setup: rigid pipe where you want it, flexible hose where you need it. For seasonal or extended stays, that means fewer leaks, less smell, and a system that’s easier to connect and disconnect without spilled gray water.

The two-piece combo is also handy for keeping a spare. RV sewer gear gets lost, cracked, or loaned out; having a matched second piece means you can reconfigure or replace on the fly.

Room for improvement

• A printed install card would help newcomers choose the right cement and reinforce don’ts (like using PVC primer on ABS).
• Including a couple of spare bayonet gaskets would elevate the “out of the box” seal experience.
• Quality control on roundness and flatness should stay tight; even minor distortion at the bayonet face can cause a drip until addressed.

Who it’s for

• RV owners converting a floppy hose setup to a semi-rigid, cleaner layout.
• Seasonal campers who want consistent hookups at home or long-term sites.
• Anyone needing an OEM-sized, rotating twist-on outlet adapter and a proper termination point on a 3-inch DWV run.

If your rig uses oddball sizes or you rely solely on ultra-flexible hoses without any rigid sections, you won’t see as much benefit from the slip-hub design. But for standard 3-inch systems, the combo slots in neatly.

The bottom line

The TonGass RV sewer adapter combo nails the fundamentals: correct geometry, a genuinely useful rotating collar, and durable ABS hubs that glue up cleanly. With proper gaskets and the right cement, I achieved tight, repeatable connections and less hassle during dumps. The fittings feel robust without being bulky, and they play nicely with standard 3-inch hoses, caps, and DWV plumbing.

I recommend this combo. It’s a practical, cost-effective way to upgrade a 3-inch RV sewer setup, especially if you value a rotating outlet and a solid, standardized termination point. Just take the time to use the correct cement, inspect and lubricate your gaskets, and give the joints a proper cure. Do that, and these adapters deliver exactly what you want from RV waste hardware: secure connections and fewer surprises.