Toilet water bubbles/splashes up when toilet bowl is full when you flush

[Dmetcalf]

This is a bit odd because we are full time and have been using this unit full-time for the past 2.5 years and this has never happened. I emptied the black tank and flushed it well (X3). When my wife was in the process of treating the black tank she normally used a gallon jug and mixes the “Happy Camper” powder in with hot water and that just about fills the bowl over half way. She then stepped on the flush pedal and water popped and splashed back and some splashed out of the tank onto the floor.
Can anyone tell me if they have experienced this problem..?

 

[Roller4tan]

Two possible issues, roof vent for the tank is blocked, or more than likely the "pooh pile" has accumulated below your toilet enough to allow liquids to SLOWLY leak thru only to clear the down pipe. When you flush the displaced air has nowhere to go but UP, instead of thru the tank and out the vent.

 

[rhodies1]

You most likely have the dreaded poop pyramid as mentioned::try putting quite. But of water in tank and leave it for awhile,this might breK up the pile,
They can be stubborn to break up.

 

[cookie]

You could try running a snake down the toilet.
It might help break up any blockage.

Peace
Dave

 

[mrcomer]

You may also have inadvertently blocked your vent pipe so you might want to snake it from the roof and down the vent pipe to break that possible clog.

 

[NYSUPstater]

Has anyone ever used the device you attach to the dump connection that runs water backwards into the tank to aid in flushing? Not sure if this will help OP's problem or not OR if Roto-Rooter will be needed.

 

[Routemaster]

I have gone on the roof and stuffed a hose down the vent.

 

[centerline]

as stated in reply #2, there are only 2 logical reasons..... the displaced air HAS to go someplace, and if it cant get down thru the pyramid and up the vent tube, its got to pass by whatever is going down towards the holding tank....

a short drain snake can help with the pyramid that may be below the commode... a wide angle spray tip on a pressure washer hose is better....

the roof vent can be blocked by spider web or wasp nest under the vent cap, or much less likely, from inside the tank if the plumbing work is not quite right.....

a blast of water or high pressure air, or a small diameter snake should clear it....

also... keep in mind that when HOT water is suddenly dumped into a cold vessel, there will be a very sudden increase in temperature, which causes air to expand quickly creating pressure, which has to go someplace.... its possible that the air expanded so fast when the hot water was flushed that it couldnt all get out the vent pipe quick enough, and so bypassed the incoming liquid....

 

[wdk450]

Well, I had this burp problem occur in my rig shortly after I moved to a new RV park recently, having done a dump station dumping before departing. I am single, and normally do not have to dump the black tank during my 21 day stays at Thousand Trails parks.
In trying to figure out what was the problem, I thought about what had recently gone down the downpipe from the toilet since just before the problem started, and I came to the conclusion the problem might be a good sized diameter "sewer trout" that might have gotten stuck in the downpipe from the toilet to the tank. I thought about it, and got my bottle of Dawn dishwashing liquid, put about 5 tablespoons of Dawn into the small clear water pool in the toilet, flushed it quickly to maximize Dawn concentration in the downpipe, and was amazed to hear a lot of hissing in the pipes for a few seconds, then a "plop" sound into the tank. I tried a regular flush again, AND NOW EVERYTHING WAS FINE - THE BURP WAS GONE!!
Evidently the "sewer trout" migrated downstream.

 

[JohnDar]

Sounds like you need more fiber if you’re blocking the plumbing like that. Musta hurt like the dickens


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[NYSUPstater]

Our son had many "sewer trouts" as he somehow managed to gum up the works in stick house many times. Then replaced Johnny Flush w/ better one and no more ups

 

[rhodies1]

I use the Velterra back flusher on my RV.I do not use the system that is installed from the factory because it’s less then effective.
Since using the back flusher I have had no issues.

 

[JohnDar]

One of the drawbacks of using the backflush to the black tank was that you had to fill the pipe to the galley gray tank before anything actually gets into the black tank. On the 3670 we had, that was a fair volume of water due to the distance. I used the tank flusher while draining the tank and then to add a measured volume back to the tank after closing the drain valve.
Had a digital water meter and NEVER left the UDC while flowing water.


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[rhodies1]

Agree but it works wonders compared to the factory flusher. I was amazed at the amount of stuff that came out of the tank when using the Velterra unit.

 

[wdk450]

Our son had many "sewer trouts" as he somehow managed to gum up the works in stick house many times. Then replaced Johnny Flush w/ better one and no more ups

RV/Boat toilets are completely different than home toilets. They are like a gravity fed outhouse versus a power water vortex flush toilet. Also, the home toilet has an "S" curve in its internal sewer piping (which helps break up solids, but also clogs more), where the RV toilet has a pretty much straight down drop to the tank from the bowl valve.