Camco 39072 Dual Flush RV Holding Tank Rinser

Holding tanks are the part of RV and boat life nobody likes to think about, right up until they start to smell. The Camco Dual Flush is the simple fix. It's a clear 5-inch polycarbonate fitting with a complete valve assembly that installs between your sewer hose and the dump station connection, and it turns any standard water hose into a two-way jet that scours residue off the walls of your black and gray water holding tanks.

Here's the problem it solves. Every time you dump, a little residue stays behind. Toilet paper, solids, and mineral scale build up on the tank walls and the sensor probes over weeks and months. That buildup is what causes odors, false tank-level readings, and eventually clogs. Rinsing the tank after a dump breaks that cycle. The Dual Flush gives you a strong, directed spray to do exactly that, without pulling the tank or crawling under the rig.

The way it works is straightforward. You connect the Dual Flush inline, hook a standard water hose to the fitting, and let the two-way jet cleaning action do the work. Water sprays back into the tank and hose while you watch through the clear polycarbonate body. That transparency is the best part of the design. You can actually see the water go from murky to clear, so you know when the tank is genuinely rinsed and not just guess at it. When the flow runs clean, you're done.

It handles both black and gray water tanks. Black tanks are the ones that need it most, since that's where solids and paper collect. Gray tanks tend to rinse cleaner and faster because they're mostly sink and shower water, but a periodic flush keeps grease and food residue from building up in those too. Either way, the routine is the same. Dump, rinse with the Dual Flush until the water clears, then close up.

One thing we always tell folks: use a vacuum breaker with it. Camco makes one (part #40395) that threads onto the setup and prevents backflow from the tank side into your fresh water hose. It's cheap insurance against cross-contamination, and you never want waste water sneaking back up a hose you might later use for drinking or washing. Keep a dedicated hose for tank rinsing and never mix it with your potable water hose. That's basic sanitation and it matters.

Install is tool-free for the most part. The fitting uses standard threads, so it connects to your sewer hose and dump connection without adapters. A wrap of Teflon tape on the threads helps seal things up and stops weeping at the connections, which is worth doing the first time you set it up. Once it's together, operating it is just a matter of opening the valve, running water, and watching the clear body.

The polycarbonate construction is tough and made to take the pressure of a hose stream, but it's still plastic, so store it out of long-term direct sun and cycle the valve now and then during the off-season so it doesn't seize. A quick flush and a valve cycle before you put the rig or boat away for winter keeps it working season after season.

Who's this for? Any RV owner, camper, or boater with a black or gray water holding tank who wants a cleaner, less smelly system without a lot of fuss. It's a small piece of gear that punches above its weight. For the price of a couple tanks of fuel, you get a tool that keeps your sensors reading right, cuts odors at the source, and extends the life of your whole waste system. First-timers find it makes the least fun chore a lot more manageable, and seasoned owners keep one in the wet bay because it just works.

It's the patented Camco design, built by a company that's been making RV and marine sanitation gear since 1966. If you're tired of guessing whether your tank is actually clean, the clear body answers that question every time.