Toilet continues to fill after a flush

[Andonno]

2020 International Dometic toilet.
I have not found our problem in past questions so I hope someone can help. The toilet continues to slowly fill after a flush. We turned it off at the floor water pipe but as soon as we turn it on the slow fill starts again. This is a new problem this week, never before. Any ideas welcomed.

[rmkrum]

Time to replace the flush valve, after checking to see it’s not mechanically deranged or something. Make sure it’s fully closing when the pedal is all the way up. Also make sure the pedal IS going all the way up when released…

I’d keep a spare handy. They do leak internally from time to time.

[ZOZ]

Hello.

Keep a flush valve handy? How about a vacuum valve? Seals anyone? What else do we need to carry? When my toilet, a five year old Thetford Aqua Magic II went bad and I had rebuilt it once, I was not doing it again with all that pooph, I just replaced it. Very simple 10 minute job. Got a replacement at Camping World.


zoz

[field & stream]

Originally Posted by rmkrum

Time to replace the flush valve, after checking to see it’s not mechanically deranged or something. Make sure it’s fully closing when the pedal is all the way up. Also make sure the pedal IS going all the way up when released…

I’d keep a spare handy. They do leak internally from time to time.

Except for the difficulty of working in that tight inconveniently located space (at least at my age) it’s easy to remove the valve, clean it up, and replace it. Same for the pedal: make sure it’s clean an operating properly. If that doesn’t work, it probably needs a new flush valve. But first: turn off the water pump!

[Fungus]

Have you tried to lift the valve? t may be getting stuck in the slightly-open position. If that shuts if off, then it needs to be cleaned up or replaced. Mine had similar issues. I finally gave up and replaced the entire toilet.

[rtaylor537]

Our valve went bad after 16 years and if we hadn't been in the trailer it would have been a disaster. Replace the valve NO replace the toilet YES.

[CRH]

I would replace the valve on a 2020 toilet.

[starlite29]

Unsure if this is the original posters issue, but it needs to be pointed out: the Dometic 300 series will continue to “pulse” water from the bowl jets for up to 20 min after flush. Often mistaken for leaky valve but it’s normal operation to ensure there is always residual water in the bowl. It’s in the manual.

[Gene]

It could be the knife style door that opens and closes at the bottom of the bowl. The rubber seal around it can become filled with nasty stuff and needs to be cleaned out periodically. I put a little wheel bearing grease in the seal to let the door slide easily. I doubt this would cause the water valve to open slightly, but in the many styles of toilets anything may be possible.

When that door does not close properly, you cannot see it, but can tell if the water drains out of the bowl regularly. I suppose if the sliding door does not close all the way, it may open the valve just enough to leak. Leaks wear out valves faster, so whatever the problem, it needs fixing. The valve can easily freeze in winter if the pipe isn't drained well and I suppose some minor winter damage could cause a valve leak.

It was a lot simpler back in the 1950's when the toilet just opened to a hole in the floor and you had to dig a hole under the trailer.

[Andonno]

Thanks everyone. You are so helpful as always. We will checkout the valve first as that seems to often be the problem.