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What to Do When Your RV Toilet Leaks or Overflows

It was Christmas Eve and we were ready to celebrate the holiday, but we weren’t ready for a flooded bathroom. We’d owned our RV for a year, and this wasn’t the first time we had to deal with an overflowing toilet.

The first time our toilet leaked was about a month after we bought the rig. As we headed to bed one night we realized the bedroom floor was wet and there was a huge puddle in the bathroom. My husband Brandon shut off the water while I looked for towels to clean up the mess. Then we went to Walmart to buy a wet/dry vacuum to clean the bedroom carpet.

We never properly diagnosed the problem, but it seemed that the valve didn’t completely shut after flushing, which allowed water to continue flowing. The toilet seemed to fix itself and all was good.

After the first incident we should’ve put in some fail-safe measures to ensure it didn’t overflow again, but we didn’t. The Christmas Eve incident was different because the toilet wouldn’t stop running. The only way to keep the toilet from overflowing was to have someone constantly pressing the flush pedal—but eventually that would overflow the black tank—or turn off the water. It seemed we were dealing with a bad valve, which meant replacing the whole toilet.

Luckily, we had a second toilet on hand and swapped the toilets out. We also had tools and PEX piping to create a shut-off for the back of the toilet, so we could turn the water off to the toilet without turning it off for the entire rig.

Toilet inside an RV
Photo: Julie Ryan

What to Do When Your RV Toilet Leaks

There are only a few reasons why you’d find your RV bathroom floor covered in water. If no one has left the shower on, it’s most likely your toilet. If it’s your toilet, it’s likely one of two things. And, we’ve dealt with both.

  1. Toilet seal: The rubber gasket that goes between the toilet and the main pipe that takes waste and water into your black tank. You’ll find similar seals on the toilets in a traditional home. 
  2. Water inlet valve: The valve that allows water to enter the toilet bowl when you press on the flush pedal. It also stops that water flow when you close the valve (by taking pressure off the flush pedal). If it stops closing, there’s a problem.

How to Diagnose the Problem 

Look at where the water is coming from. If the water appears at the bottom of your toilet (near the floor), the problem is most likely the toilet floor flange seal that will leak wastewater every time you flush. It could also be a leak at the water valve or water line connection that will leak anytime you have pressure on the fresh water system, leaving clean water around the base of the toilet. If your toilet is overflowing, or if water is continually running into the bowl when no one is pressing the foot pedal, this is an indication that the water valve is defective and not fully closing when the pedal is released.

Leaking toilet in an RV
Photo: Julie Ryan

What to Do When the Floor Seal Leaks

  1. Turn off the water.
  2. Mop up the mess and wrap a towel around the base of your toilet. Anytime you’re dealing with a toilet, you should wear rubber gloves and disinfect any leakage area since it could be wastewater.
  3. Drain your pipes. Just as you do before you hit the road, turn on a faucet (or two) and let it run until all remaining water in the lines has been emptied.
  4. Drain all water from the defective toilet. You can do this by pressing on the flush pedal until the bowl is empty and no water is running into the toilet or onto the floor. Once the toilet is drained, turn the water back on and let it sit until you have the necessary parts to fix it. Just don’t use it—and make sure to turn the water back off before you try to replace the gasket.
  5. Buy a replacement rubber gasket. Note: Not all floor flange seals are the same. You’ll need the model number from your toilet to make sure you have the correct seal for it.

How to Replace the Rubber Gasket

  1. Make sure the water is off to the rig and the toilet has been drained.
  2. Have a large trash bag on hand. 
  3. Disconnect the water from the back of the toilet. 
  4. Unscrew the nuts at the base of the toilet that holds it to the floor.
  5. Lift up the toilet and place it upside down in the garbage bag—use the bag to keep your floor clean from whatever may drip out of your toilet.
  6. Remove the old gasket from the base of the toilet and clean the area.
  7. Insert the new gasket into the base of the toilet.
  8. Set the toilet back in position, reattach the toilet to the floor, and reconnect the water lines. Depending on your toilet, it may be easier to reattach the water lines first and then reattach the toilet to the floor.
Old toilet gasket in an RV
Photo: Julie Ryan

What to Do When the Water Valve Leaks

If there’s water leaking from the valve itself (and not the water connection to the valve) or if the water valve continues to allow water into the toilet after the pedal has been released, then the valve will need to be replaced. If water is leaking from the connection line to the valve, you may simply be able to tighten the connection or replace the cone gasket in the water line fitting. Depending on your toilet model, water valves can be very simple or very difficult to replace. You’ll need to look up procedures for your specific toilet to see if this is something you can tackle.

Lessons Learned

While you have the toilet removed, you may want to install a water cut-off into the water supply line at the back of the toilet. Houses usually have a way to turn off the water at the toilet, sink, and other points rather than turning it off to the entire house—you can do this in your RV as well. 

To do so, you’ll need a few tools, some PEX pipe, and a shut-off valve. When we swapped our toilets, we added a shut-off valve so that if something like this happens again, we can just turn off the water to the toilet. We also purchased a small water detector that sits behind the toilet so we’ll be alerted of any leaks before they cause a bigger problem. 

Cut-off valve for RV toilet
Photo: Julie Ryan

If your rig is more than a few years old, you may want to consider replacing these gaskets as a preventative measure in order to avoid any unexpected flooding. Hopefully, with the right planning and maintenance, you can avoid an RV plumbing mishap.

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