Close this search box.

rv trips & travel

My RV Toilet Keeps Filling Up – Here’s How to Fix It

As an RV owner, having a private toilet on the road can be great. If you are parked far from “civilization” you can have some of the comforts at home within your RV. Even if you are in a city, you can avoid having to use public restrooms – which can be a bit unpleasant.

Like home plumbing, RV toilets can have their fair share of problems. They work in a similar manner to your home plumbing system. The plumbing system has the ability to carry fresh water in and waste water out – and sometimes it won’t stop bringing water in.

If your RV toilet keeps filling up too much, it might be time to look at the hardware that brings water in. Your RV has a couple ways of getting water into the toilet, and a couple potential problems to overcome. We’ll talk about your water valve as well as expectations for how much water should come in.

How to know if my RV toilet has too much water

You might be unfamiliar with your RV toilet compared to a regular toilet, like the one at your house. An RV toilet might fill up a bit more than you normally see from some low water use toilets as well, especially in an RV.

An RV toilet bowl should have 1 to 4 inches of water and without adjusting settings, the toilet should have close to the same amount of water in the bowl every time. The water should also suddenly stop coming out.

If your water keeps flowing above 1 to 4 inches, you could have a problem. Given how fast water comes out, an overflowing toilet is entirely possible.

Why is my toilet overflowing or filling up?

An overflowing toilet or a toilet that won’t stop filling up are likely the same problem. The water valve is likely stuck open. The water valve is located inside the toilet thoug it’s normally located in or near the tank on a regular toilet.

The water valve uses some mechanics to stop the flow of water into the toilet, keeping water in your lines to wait for the next flush. The valve works quite similar to the shut off valve for your toilet, only it’s automatic and doesn’t need to be stopped by hand.

If your RV toilet has a “flapper,” this might also not be working correctly. This is more common with RV toilets with tanks. 

If your toilet is filling up with waste water, you have a totally different problem. Your black water tank is likely backed up or you have a clog somewhere in your black water line. A clog or backup causes waste water to return to wherever gravity takes it – potentially including the toilet bowl.

What can I do about it?

Toilet overflowing with fresh water

Water Valve

Since this likely results from a stuck water valve, you have a couple choices. The first is to forcefully flush your toilet and see if the water movement can open the valve. The only way to really know if this works is if the water stops flowing when it should.

You might have to forceful flush a few times for this to truly take effect.

The other option is to replace the water valve. This is a bit more difficult though it’s possible without a plumber. You’ll need to order a new water valve and remove bolts from the bottom of your toilet with a wrench. You might want towels too!

In the event that your valve remains stuck, you can also just turn off the water to the toilet.


If your RV toilet has a tank, this is another potential course of action. The “flapper” is a rubber or plastic piece on a rod that prevents water from flowing into the bowl. The flapper’s rod might not be dropping it in the right place, or the rubber itself might be torn.

Either way, replacing the flapper is easy as finding one at a hardware store. The flapper can be replaced in a few minutes and you’ll see immediate results. The hardest part might be ensuring the flapper comes down at the right speed.

Toilet overflowing with waste water

This article is more about fresh water, but getting waste water to stop flowing likely needs a plunger or to have the black water tank drained. These are the two most common reasons why you would have overflowing waste.

Other options here include using a black tank cleaner poured into the toilet to remove sludge. The cleaner usually has to sit in the toilet and waste line for a while before you flush again, but can be helpful both to prevent overflowing and to keep your plumbing clean.

Shut off Valve

Not every RV toilet has this, but it can help. Some RVs have a shut off valve that applies to individual areas that use water, like your toilet, sink, and shower. Others have one shut off valve that supply water everywhere.

This is easier with just a toilet shut off valve (which can be installed) to turn the shut off valve off to keep water from flowing through. The idea is temporary, of course, and could be annoying to have to turn off and on to use the toilet properly.

The shut off valve is also a good way to stop your toilet from potentially overflowing and getting your whole bathroom wet.

You’ll then want to go refer back to previous instructions about hunting down the source of the problem and fixing it.


Your toilet can overflow for a couple of reasons, mostly having to do with hardware within your toilet. You can sometimes fix the issue by flushing the toilet harder than normal and repeatedly to unlock your water valve through force. Other options include replacing that valve.

Take a look at our instructions above to understand what is causing your toilet to continue filling with water. 

Scroll to Top