My toilet burps....

Mine only did this one time I had the DW go out and drain and flush the black tank, I had the water Y connector and both the fresh water and black flush hose hooked up. She didn't quite get the flush hose turned all the way off and later that evening it burped when i flushed it, I thought boy that's weird. Went to bed and the next morning it did it again, I then looked closely and the tank was almost full! That's when I went out and looked and found the valve just barley on. Could have been a terrible moment close call for sure. I now leave the hose off of the Y connector until needed. Doubt that's your problem given the description but that I would toss it in so no ones else makes the same mistake.

This is probably not likely your problem but there are some people who never get the word to keep the dump valve closed until the tank gets somewhat full. If you keep the sewer valve open when hooked up to a sewer, the solids don't get carried away and build up a pyramid in the tank, right below the toilet. The result eventually means that the toilet stops up.

I actually bought a used fifth wheel trailer less than a year old and found that that situation existed when I bought it. The previous owner had all sorts of tools to combat the problem but had no idea what he was doing wrong.

As others have pointed out, it is a venting problem. The issue is that the vent is blocked, for whatever reason, so emptying the toilet pressurizes the black tank. That pressure has to go somewhere, so it comes back up through the toilet, causing that burp.

When this happened to me it was caused by letting the black tank get to full and some TP got into the bottom of the vent pipe and stuck. The only solution was to gon on the roof and roto rutor it out. Try a hose and it din't work.

Full/near full black tank..........time to dump

Not anywhere near being full.....
1) Vent to roof is obstructed
2) Vent line has fallen down too far inside tank
3) Pop Pyramid is building up under toilet line

#1 & #2.....some one needs to go up on roof, locate vent for black tank, remove vent cap.
Then check if top of vent line is at/near roof line or has fallen down below roof line.
If dropped grab with pliers/vise grips etc and see if line can be pulled back up. Secure with couple of screws thru side of pipe into roof structure (unless vent line is accessible elsewhere.....then strap it)
At/near then vent line hasn't dropped down into tank and may be obstructed.
To clear....
Check for any debris that can be removed (birds nest etc) and then stick a garden hose with nozzle on end down into vent line several feet, then with
black tank drain valve open turn on water and blast down into vent line until line is clear and free flowing.


#3.poop pyramid
Garden hose with nozzle down thru toilet blasting away with tank drain valve open (if toilet sits directly over tank and line is short shine a flashlight down into tank and inspect)

Can you keep a close watch and see if it burps when it's time to dump? If so, this is normal.

Its doubtful that the blockage is at the roof. Possible but unlikely.
If it burps all the time then there definitely is a blockage in the vent pipe somewhere, probably a result of the black tank sludge being pushed up the vent pipe when the tank is completely full and then hardening. If thats the case, then someone will have to either force water down the vent pipe or using a rod long enough to clear the passage.
If it only burps when the tank is nearly full, then its doing what its suppose to do. the sludge level raises to the vent pipe level and doesn't allow the tank to breath when flushing.

olfarmer wrote:
Check your roof vent and make sure it is not plugged.

Is there a way to fix this without climbing up on the roof?
(I'm handicapped.)

Mine burps when it is nearing full which may tend to block the vent. olfarmer is right on.

Check your roof vent and make sure it is not plugged.