Which tank lever do I pull?


By Russ and Tiña De Maris

Experience teaches us that as we get older, one of the things we miss the most is our minds. Well, from this corner of the galaxy we can tell you that. If you haven’t begun to lose your mind, cherish the moments you have. With time, you too, can join the rest of the disjointed. Like this poor fellow who writes, “I can’t seem to remember which of the tank levers on my RV is for black water, and which is for gray. Any suggestions?”

puzzledNormally, such a confession wouldn’t be based on memory. Rather, we expect to see this kind of configuration confusion come from some poor soul who purchased a used RV and the previous owner had the memory issues. But be that as it may, it could actually become an issue.

The answer to figuring out this problem has a couple of variables. If your dump valves are basically “uncovered” so you can see the pipes that go into them, the problem is often simply resolved. The black water line is typically large – three-inch size pipe – while the gray water is commonly two-inch, or even inch-and-a-half size pipe feeding out to the dump valve.

OK, but what if – what if the pipes are the same size, or what if those pipes aren’t visible? If you can’t easily remove the obstructing cover to get a good look at the supply line, or if they truly are both the same size, then life gets a bit trickier. Can you see the holding tanks themselves? It’s likely that the pipe runs out to the dump valves will be more-or-less direct. That is, if the black tank is more rear-ward than the gray, it’s likely the most rear-ward dump valve will be black water. But how do you know which tank is which? Ah, students, equip yourself with a chuck of 2″ x 2″ lumber, three feet long. Shut off the pump and the city water supply, step on the lever as if you were evacuating your toilet, and GENTLY push that 2 x 2 down the throat of the toilet, while holding the valve open. Now gently tap tap tap the bottom of the holding tank while your able assistant under the rig is listening for the tell-tale sound of tapping.

Finally, here’s the “when all else fails” answer. Get thee to the RV supply store and purchase a clear, dump elbow. This clever attachment hooks onto the outflow of your rig’s drain system, and acts as a go-between the rig and your sewer hose. At the dump station, put on the dump elbow, attach the sewer hose, properly insert the dump hose into the dump station port, and prepare to quickly pull (and be ready to shove back) either one of the dump levers. If you see that awful brownish liquid in the elbow, all well and fine, complete dumping. You’ve found the lever for black water. On the other hand, if you see gray looking drool, quickly slap the lever back – you’ve found the gray water handle. Dump the other one first, then go back and dump the gray.

Once you’ve properly ascertained which lever does which job, you’ll want to code them in some way to aid your memory. Got a label-maker? Equip it with plastic tape and print out a label for each tank. Or use electrical tape as a tag for the black water, and maybe duct tape as a tag for the gray. Or draw a little diagram and post it in a compartment close to the dump levers.

Now if I could just remember where I put the keys to that compartment . . .

##rvt754 & RVDT1204

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11 months ago

I’m surprised nobody mentioned the way to find out which tank is which without having a go to a hardware store and buy wood or having a helper even. Empty out all of your tanks close the valves and put a hose in the kitchen sink or the toilet. Let it fill up the tank then go back and pull a handle. If you put the hose in the toilet filled the black tank that should be the only tank that has water in it.

11 months ago

I can’t believe someone suggesting the 2 x 2. Your suggestion on the clear section is perfect, that item is a must have so you can tell if its finished running yet. I also found out on my last two pickup campers that the Gray tank is higher than the Black so I bought a valve that you connect to bottom of the clear section and when the black stops running close that valve and open the Gray and half of it runs into the black tank flushing it out with soapy water. then close gray and open black and see how much it cleaned out that black tank. Has worked great for the last several years.

11 months ago

just label the handles and/or the pipes. this is not rocket science.

11 months ago

After I figured out which lever was which in our old motorhome, I covered the gray water handle with gray duct tape and the black water handle with black duct tape.

11 months ago

label marker is the perfect answer. I use mine almost every day. Biggest use, when getting a new electronic item, I immediately label the wall wart. They are not all the same. I also traced and labeled the fuse box. Keeps the guessing down.

George McMeen
4 years ago

Black and Gray paint is cheap—–just paint the handles.

John Connaughton
4 years ago

Wow, my black tank has a black handle and my gray tank has a gray handle. I didn’t know that sometimes this is not the case.

11 months ago

Ours is the same. Wouldn’t it be smart for ALL RV manufacturers to do it that way then there would be no guessing.

Mel Goddard
4 years ago

On my Airstream, the levers are’backwards’ as compared to the ‘norm’.
Also, the levers are similar in colour, so I painted my grey handle white, and left the black tank handle black.

4 years ago

I wrote gray next to the valve for the gray tank….provisimo!

Richard Smith
4 years ago

I painted the Black Tank valve handle BLACK and left the Grey Tank valve grey in color. These were replacement valves that had to be installed when the original ones were leaking. The label symbols that are on the panel of the service bay are reversed and therefore incorrect so painting the handles was the next best remedy for anyone not familiar with my coach that palns to dump the tanks