Friday, October 7, 2022


Ask Dave: Our toilet will not hold water in the bowl. What to do?

Dear Dave,
I’m new to RVing. I have a 2018 Winnebago travel trailer and no one told me how to store it. We are out at least once a month, but COVID made it a little harder to get out. Anyway, the O-ring in the toilet is leaking. Is there a way to change it? Our camp place said they have to take the toilet off to replace it. I’m pretty good with working on things. Is there something I can do or use to maybe rehydrate the ring? It’s the flange at the top that holds the water in the bowl. Thank you. —PJ

Dear PJ,
Great to hear from you, and nice to see the “PJ” nickname as my grandfather was “PJ,” as well.

I have been in this industry for more than 30 years and the #1 issue I see is inadequate owner education from manufacturers and most dealers. I have conducted more than 1000 seminars throughout the country. Even seasoned RV veterans come up to me after a seminar and tell me they had never heard of doing some type of maintenance that was covered. Another issue is the owner’s manual just covers the basics of the RV.

OEM manuals have maintenance suggestions

Then there are dozens of other manuals from the Original Equipment Manufacturer (OEM), which are the companies that make the individual appliances and other components such as your toilet. And who reads the owner’s manual for a toilet? This is unfortunate as most OEM parts have maintenance suggestions for their components such as a lubrication for the seal of your toilet.

Typically the rubber flange or spade seal of the toilet bowl does not need much maintenance. I’m surprised a unit that is only about 4 years old has a bad seal. However, it is rubber and can dry out and crack or not seal properly. This can occur especially when we subject these components to extreme temperature changes during storage. That could be below zero in the winter and hot humid temperatures in the summer, as we just let the RV sit and do nothing for climate control. Imagine if you let your house sit for months with no temperature or climate control!

Recondition the seal

The first step I would suggest is to clean the seal extremely well to get any particles such as calcium, lime, or rust off the underside of the rubber gasket.

You might even need to use a light sandpaper or plumber’s emery cloth to smooth the surface.

Treat the rubber toilet seal

Next I would recommend treating the rubber seal with 303 Protectant or ProtectAll All-Surface Care. Both are designed to condition rubber and could soften the material and condition it enough to seal.

Then I would use some of the Thetford seal conditioner and let it sit for a few days. You might not need both, but it won’t hurt. This is the product you should dump into the toilet when you store it for any more than a few weeks.

If this does not resolve the leak issue, then you probably need to replace the gasket. That typically does require the toilet to be removed, as you will need to access the seal from the bottom of the toilet. This is not a relatively hard job if you have moderate DIY skills.

Not knowing what type of toilet you have, here is a schematic of a typical ball valve type toilet used on several of the Winnebago motorhomes.

You need to take off the lower cover and then you will see the lag screws that secure the base to the floor. Here is the flange after a toilet was removed from a 2003 Winnebago Brave.

Check the spring cartridge

One other thing to look at is the spring cartridge that might have a weak spring. I had an earlier question from a reader that stated the bowl leaked unless they let the pedal snap back in place or pushed up on the pedal. This would indicate the ball or spade was not making the full travel back to the seal and that would indicate the spring was weak.

You can replace the spring; however, it’s easier and less time-consuming to just replace the cartridge in this situation. Other models might just need a new spring.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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7 months ago

I have a 2022 that the half bath toilet would not seal. I put some cooking oil on the seal and rubbed it in real good and hasn’t leaked since! When I wasn’t full time I would treat my seals with the oil at least once a year.

Carl Hanson
7 months ago

I have a Dometic 310 porcelain toilet and the ball valve seal can be replaced without removing the toilet from the floor. I just have to keep the valve open, pull out the old seal and replace with a new seal. Very quick and easy. We live in northern Wisconsin, so the freezing weather tends to dry out the seal faster. We put Vaseline on the seal after winterizing to help keep it pliant.

7 months ago
Reply to  Carl Hanson

This! And probably costs less and takes less time than buying lubricants etc. It’s rubber, you pull on it, it comes out. Takes a little dexterity to get the new seal in. And be sure everything is clean first.

Before you remove a whole toilet, be sure you can’t just pop the gasket out from above.

Jim Coker
7 months ago

We use plumbers grease. Shut off water, hold pedal down and apply plumbers grease to top and bottom of seal. Works great. You can get it at lowes or Home Depot.

Seann Fox
7 months ago

To clean the toilet seal I use one of those dish washing thingies with foam fingers from the dollar store, just don’t use it in the kitchen after that…🤢