Having a mobile bathroom in your RV is quite helpful on the road and keeps you from having to use public facilities that often arenโt as clean as youโd like. With having your own bathroom also comes the possibility of extra maintenance though. When your RV black water tank is clogged it’s one of the grossest issues you can deal with in an RV.
Thankfully, itโs not that difficult to unclog your black water tank, in the event it does get clogged. There are also more than a few ways to tell if your black water tank is clogged.
The first step is knowing that your black water tank is clogged. Weโll discuss a few observations you can make. Finally, using ice or other methods might help.

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How do you know your RV black water tank is clogged?
Before you begin methods to unclog your RV black water tank, make sure itโs actually clogged first. Hereโs how to know that your black water tank is clogged
It doesnโt drain
Try to drain your black water tank, using a clear hose adapter if possible. If you donโt see solid waste coming out and you know there is solid waste inside, you probably have a โpoop pyramidโ or something like it.
You can smell it
Having a clog somewhere in the line for your black water tank can prevent solid and liquid waste from moving into the black tank โ leaving it in the black water line for your nose to inhale.
Itโs coming out of your toilet
This could mean you are overflowing and clogged. Having solid and liquid waste backed all the way up to your toilet is a bad sign indeed. First, try draining it, then if draining it doesnโt help โ try the upcoming unclogging methods.
How do unclog your black water tank
There are a few tried and true methods. Weโll start with the easiest first.
Ice
Ice is one of the easiest methods. Either buy a bag at a gas station or grocery store, or freeze ice cubes in your freezer. Empty the tray or bag (or at least part of it) into your toilet.
Drive the RV around for a little bit to allow the ice to flow throughout your tank.
This method can break up clogs by having solid pieces of ice ram into the clog to attempt to remove it.
When done, attempt to drain the tank again and see if solids and liquid comes out.
Boiling water
A clog can be removed with ice, or melted with hot water. Melting a clog sounds gross, but it works.
Get a big pot of water and boil it on the stove. Ensure that no one is in your way on the path to the bathroom.
Slowly dump the pot of boiling water into the toilet and flush if necessary. The hot water can melt clogs in the line and potentially break up any clogs inside the black water tank itself.
Like with ice, try to drain your tank and see if anything solid or black/brown comes out.
Plunger
The problem could actually be simple and within your lines. Get a plunger and put it in the toilet, placing it directly over the toilet drain. Keep in mind this doesn’t work with majority of RV toilets. However, some RV’s have upgraded toilets that are more like those in a home.
One thing people tend to do incorrectly with a plunger is being too gentle. When you get a good seal, give the plunger several good pushes to create a vacuum and potentially push a clog around. Doing this too gently wonโt do much, if anything.
Tank cleaner
This is the second to last resort, though actually calling a plumber wonโt likely be necessary unless there is something besides waste caught in your tank.
Tank cleaner contains enzymes and acids that literally at a clog at itโs source. This means that the tank cleaner will help dissolve mounds of toilet paper or solid waste.
Youโll want to wait a little longer with tank cleaner. Ice and hot water will begin to change temperature immediately, so draining earlier is OK. Wait a few hours if not overnight with tank cleaner to let it dig in.
RV owners can then dry to drain the black water tank. You should see some solid waste this time.
How to prevent a clogged tank
One of the biggest things you can do to prevent a clogged tank is to keep some freshwater in there when you maintain and drain your tanks. The dreaded โpoop pyramidโ is most often caused by having solid waste or excess toilet paper in an overly dry tank with no other liquid, including urine. Urine or water can help keep solid waste moist so it flows naturally and doesnโt stick to the tank or pile up.
The above also means using lots of water when you flush your toilet. A lower flo toilet might be contributing to the problem.
Filling your black water tank with some water can be quite helpful in this scenario.
Also, use RV friendly toilet paper. To be fair, there arenโt many toilet papers that are truly RV unfriendly, just be sure you are using the right kind. For those who tend to pee alot, like me, keep a garbage can with a bag in it and put all your toilet paper in that if you are just doing number 1. My can gets emptied daily and this helps to not clog the tank.
Keep your black tank closed when not in use. This literally means that you should close your black tank valve right away after draining. Donโt store your RV with anything in the black water tank, either.
Conclusion
Your RV bathroom is a pretty convenient place to use the bathroom on the road. Thankfully, the bathroom is relatively easy to maintain though itโs different from your home toilet. The above advice has some easy methods like boiling water and ice, and some methods that need a hardware store trip like tank cleaner. You should clear out your tank occasionally anyway, but using tank cleaner will certainly work with a bit more effort and time.
Just keep water in your toilet tank and you shouldnโt run into many issues of having the tank clogged, as itโs most commonly caused by larger objects stuck in the tank, or overly dry waste. And don’t forget to blow out all your water lines when you store your RV for the winter.
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