How to Unclog a RV Toilet Holding Tank

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Your RV provides solutions for lots of amenities you need while on the road. You can get a shower, sink, stove, bed and your own bathroom. All without having to use public facilities unless you want to.

With that comes needing to maintain your own RV toilet holding tank – the place where your liquid and solid waste goes. This RV toilet holding tank can get clogged and become pretty gross, even with some maintenance. 

Unclogging your RV toilet holding tank can be done with a couple methods including using ice or chemicals. The backlog of waste can be loosened up and drained out with a little bit of patience. Here is more detail about what to do:

Determining if your RV toilet holding tank is clogged

There are a couple of signs that your RV toilet holding tank is in fact clogged before you start the process of trying to unclog the tank.

Backed up

If your waste will not go down, your RV toilet holding tank or the line leading to it are likely clogged. It’s also possible that your tank is actually full, which leads to our next step.

Can it drain?

We assume you are somewhat familiar with how to drain your RV toilet holding tank. Consider getting and using a semi transparent hose attachment so you can see what’s in the hose coming out. If it’s only liquid or nothing comes out, you probably have a problem with solid waste build up.


Not that we expect your toilet to smell good, but it could smell extra bad when connected to a clogged holding tank. It’s also possible the clog is somewhere in the line leading there. Fermented solid waste that is sitting in your tank can tell you something is not normal down there.

How do I unclog the RV toilet holding tank?

Thankfully, there are a few ways to rid your holding tank or whatever is clogging it. Chemicals work, but so do other methods.


That’s right. Either dump an ice cube tray into the toilet or buy a whole bag from some place that sells ice cubes – though you won’t need the entire bag.

The next step is to take a quick trip around with the RV to get the ice moving and capable of using it’s relative weight to knock out any clogs. 

After you are done driving around for a bit, try to drain the tank again.

Hot Water

This is more for if the clog is in the lines leading to your tank, but can still help. If your toilet is literally backed up, this might not be as good an idea because we are talking about almost boiling hot water.

Pour it into the toilet. Of all things, hot water could melt or dissolve the clog. Let it sit for a little while and try to drain the tank.

Tank cleaner

At some point, a clog or “poop pyramid” can get so bad you have to use some tank cleaner. These aren’t necessarily toxic for the environment, so much as the scenario in which you’d need them is just gross.

In most cases, an RV holding tank cleaner has enzymes and other ingredients that are capable of eating or moving organic matter.

Follow the instructions on the bottle, but your best bet is to pour it into the toilet and let it sit for a while, preferably overnight. 

Drain the following day. If this doesn’t work, you might want to seek some outside help.

Use a snake

A snake is a mechanical auger that can be sent into your toilet or holding tank. The snake is designed to break up and push out clogs. The snake auger itself will have instructions. Our only suggestion here is have disposable gloves, a trash bag, and goggles because you might have solid wate come back with the snake.

A snake might not be able to do much within the holding tank itself as it’s meant to clean pipes.

How to prevent a RV toilet holding tank clog

There are a couple consistent things about our recommendations to remove the “poop pyramid” or other clogs: Liquid.

Clogs tend to be in place either because they are bigger than their surroundings, or part of them is dried and stuck. Either way, your RV’s plumbing system is meant to carry liquid and water or a holding tank cleaner can help dissolve whatever it is. 

That said, the next best thing you can do is keep your RV toilet holding tank somewhat full of water. That doesn’t mean not draining it completely, but it’s certainly OK to fill your RV toilet holding tank with some fresh water in order to keep the inside from being bone dry.

If you were to flush down a large amount of waste or toilet paper into a dry tank, it has the chance to dry up and become practically fossilized. These situations are what leads to tanks that won’t drain. If the clog forms in the wrong part of the tank, you could see backup.

Also, be sure to use RV and septic safe toilet paper. Some toilet papers work better when around what amounts to standing water. While most toilet papers do work for an RV septic system, there are kinds that are better with a constant moving water source like that of a home sewer system.


Getting your RV toilet holding tank unclogged can be a gross problem. Thankfully, there are a variety of ways to ensure that you can use your toilet as you need, ranging from ice to hot water and chemical cleaners. 

Your RV toilet function is pretty important, especially for off the grid campers. Keeping some water in the tank can help prevent clogs.

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