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RV Toilet Not Holding Water? How to fix it.

Using and flushing a toilet can be a very automatic process – to the point where don’t notice problems right away. An RV toilet that is not properly holding water is not something you are likely to catch immediately. You might instead of drawn to attention by looking in the bowl, or by the extra smell that comes from a lack of water to absorb doors.

RV and home toilets alike can experience issues holding water. These problems are often fairly simple to solve and just require a little investigation.

Among reasons why your RV toilet isn’t holding water can be an issue with the toilet bowl, a misdirected pipe that fills the bowl, or a switch having a problem that allows the drain to drain completely. All are fixable, of course!

My RV toilet is not holding water – is your floor wet?

If you walked into the bathroom and noticed a big puddle under your toilet, your bowl might literally not be holding water. 

Broken Toilet Bowl

Toilets are usually made of porcelain or plastic, so this isn’t especially common, but it’s possible. A simple separation between the bowl and a seal can cause a leak. Plastic and porcelain can crack, too!

The best solution is to either find a way to recreate the seal or just replace the toilet. The bowl isn’t exactly a mechanical part that can be easily replaced individually, and if you are going to put that much effort to removing the bowl, it’s worthwhile to do the whole thing.

Bad Flange Seal

The flange seal goes by a few names: Blade seal, O-ring, wax ring, and probably a couple more. The purpose of the flange seal is to provide a waterproof connection between the base of your toilet, the floor, and the sewer or black tank pipe it’s connected to.

Flange seals are usually made of wax and last a long time – even decades. When a flange seal goes bad, water can leak out and end up beneath the toilet and on the floor.

In this case, the toilet is not holding water because it’s leaking out through the bottom.

You can certainly replace a seal without replacing the entire toilet. You’ll need to find a new seal at the hardware store, dismount the toilet, remove the old seal, then put the new one down.

A bad deal is one of the most common problems we encounter. One way to prevent a broken or bad deal is to occasionally unmount the toilet and lubricate the seal. Manufacturers like Thetford, which is a very common RV toilet brand, make a liquid seal for the purpose. You could also use vaseline. 

A dried seal is more likely to crack as it solidifies and faces continued pressure during flushing. Knowing when to lubricate the seal is rather difficult to know, but any time you actually move your toilet you should do it out of convenience.

Other problems where the toilet won’t hold water in the bowl

Issues with the pipes filling the bowl

Check your toilet tank after you flush. Most RV toilets have a similar process to home toilets that send water into your toilet bowl via a vertical pipe in the tank.

It’s entirely possible that your toilet bowl isn’t filling because the tubes that bring water into the tube are just not spraying water to the right place. 

When the water does start coming out of the top tube, just heck to make sure it’s going down the tube into the bowl. If this is not happening, redirect the tube to the right place. If the tube is broken, replace it.

If the problem with a misdirected water tube continues, you might start to notice it pouring out of the tank – and that’s an obvious sign!

Flushing problems

Some RV toilets have a flip down flushing wand that is on the front, and often bottom right of the toilet. The purpose of this is to keep water in the toilet until it’s time to flash. 

This lever can also develop a problem where it doesn’t close completely, and doesn’t make a complete connection that would stop water. In this case, the water is going to flow straight to your black water tank instead of the floor.

How would you notice this? The top part of this lever will no longer contact the toilet – and it might leave even a very small, barely noticeable gap. You can attempt to lubricate this lever to see if it unsticks and makes the complete reach to close off the sewer pipe.

This one is harder to detect because how often do you really look at the lever that makes complete contact with the outside of the toilet? It’s really tough to notice the difference until the water starts disappearing from the toilet bowl and your black tank fills up fast.

Maybe not a problem? Is it supposed to have water in the bowl?

Some people are very accustomed to home toilets that have about one gallon of water in the bowl, depending on how much you let in.

Not all RVs come with toilets that include resting water. It’s possible that your RV toilet drops the waste straight into the black tank without any water to filter it. The most obvious sign on this situation is when the toilet lacks a flushing handle on top or bottom.


While we hope it’s not, having the water leak out of the bowl in your toilet is a messy and freaky situation that can often be fixed by replacing a seal or replacing the whole toilet. Other related problems are often simple mechanical issues within the toilet that can be fixed by a bit of lube, or just moving a hose a little bit.

The water has to be going somewhere – you just have to find where it’s existing and figure out how its getting there.

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