Toilet burping...

[TheCatsRV]

I have a problem with the toilet burping inconsistently in my class A (been doing this on and off for the past 2.5 years we've owned it). For this season, it was o.k. initially when I started flushing out the antifreeze, and then for the first 2 days of a camping trip. The black tank was drained at the campground prior to our stay (and hence use). All was fine until 2 or 3 days later when it started to burp again. Drained the tank at the end of the 4 nt camping trip again. Still burps.


I climbed onto the roof and found the two sewer vents. Figured the rearmost of the two was the blackwater (forward one - just forward of the shower stall, black is just aft of the shower stall - presumably connected to grey) so I removed the cap and put a ~12' snake down the vent pipe. Not sure how far it reaches but it got a bit mucky. Also took a hose up and ran water down the pipe.


Going camping again next weekend, and will empty the tank(s) before and after. Just wondering what other issues and (more permanent) fixes there might be.

[Gooma]

Bad burritos! Make me burp every time I eat 'em.
However, I don't think that's your problem. I would say you may have fixed it by cleaning the vent.

[DarkSideJeep]

Originally Posted by TheCatsRV

I have a problem with the toilet burping inconsistently in my class A (been doing this on and off for the past 2.5 years we've owned it). For this season, it was o.k. initially when I started flushing out the antifreeze, and then for the first 2 days of a camping trip. The black tank was drained at the campground prior to our stay (and hence use). All was fine until 2 or 3 days later when it started to burp again. Drained the tank at the end of the 4 nt camping trip again. Still burps.


I climbed onto the roof and found the two sewer vents. Figured the rearmost of the two was the blackwater (forward one - just forward of the shower stall, black is just aft of the shower stall - presumably connected to grey) so I removed the cap and put a ~12' snake down the vent pipe. Not sure how far it reaches but it got a bit mucky. Also took a hose up and ran water down the pipe.


Going camping again next weekend, and will empty the tank(s) before and after. Just wondering what other issues and (more permanent) fixes there might be.

The burping will also happen if the tank becomes too full or if your "deposits" backup in the tank and create a blockage in the tank vent. Another possibility, do you by any chance leave the Black valve open when you are hooked up? If so, that is a big NONO. If you leave the Black valve open all the water drains off leaving the solids behind. The solids then pile up under the entry to the black tank and eventually block the vent.

[Old-Biscuit]

Toilet burps:
Toilet to black tank line obstructed
Area directly below toilet line has a poop pyramid
Black tank FULL
Vent line obstructed

[DarkSideJeep]

Originally Posted by Old-Biscuit

Toilet burps:
Toilet to black tank line obstructed
Area directly below toilet line has a poop pyramid
Black tank FULL
Vent line obstructed

"Poop pyramid" Thanks I could not think of what to call it.
Actually, puts the image of stalagmites in my mind. The Poop pyramid just happens a whole lot quicker.

[SafariBen]

I've seen some really bad venting or lack of it in household drain plumbing, and it still usually works mostly. But a black tank without a vent (unlike houses they only get ONE 1 1/2"!) is NASTY. The vent should not be mucky unless you reached the tank. I wonder if the shower is teed into the vent line (legal) and it has a hairball? Otherwise, I'd pour a soap or disinfectant down that vent a few times, a few days apart then rinse for a while. Dawn, quaternary ammonia (alkyl benzol dimethyl ammonium chloride, in everything before and during the pandemic, Forest 5 is a handy foaming version) or even lye, dissolved in a gallon of water and rinsed down. Make sure the tank isn't empty if you use lye, to dilute once in the tank.

[TheCatsRV]

Thank you all. Just a few more observations (and the problem is intermittent, not constant).

• Just wondering if I'm not priming the black water tank with enough water after emptying.
• Tank seems fairly small (and is pretty much right above the toilet). Plumbing isn't straight so I can't see inside. Did use the magic rinse wand (just goes around the elbow out of sight) too but I can't see down.
• Don't think it was an issue with it being too full.
• Were dry camping (usual for up here) but have read enough never to leave the black or grey water valves open even with hookups. Just flush when we go.
• I'll try the Dawn/detergent trick for the short drive to the campground and hope it works. Not sure where to get lye from.

Do occasionally have an issue with the grey water backing up into the shower pan when underway on twisty roads. Grey water tank shouldn't be that full so just wondering if the run from shower to tank may have a negative incline so it's not draining fully. Shower pan drains fast otherwise. I don't think that's got anything to do with the toilet burping issue though.

[Old-Biscuit]

Originally Posted by TheCatsRV

Thank you all. Just a few more observations (and the problem is intermittent, not constant).

• Just wondering if I'm not priming the black water tank with enough water after emptying.
  After dumping flush 2 FULL Toiet bowls back into black tank ---helps flush toilet to tank line and keeps tank bottom wet
• Tank seems fairly small (and is pretty much right above the toilet). Plumbing isn't straight so I can't see inside. Did use the magic rinse wand (just goes around the elbow out of sight) too but I can't see down.
  Waste tank are typically tapered...shallow end at 'entry' sloping to deeper end at 'exit'
• Don't think it was an issue with it being too full.
  When you cleaned vent line you stated it came out murky. Vent line should be clear now
• Were dry camping (usual for up here) but have read enough never to leave the black or grey water valves open even with hookups. Just flush when we go.
• I'll try the Dawn/detergent trick for the short drive to the campground and hope it works. Not sure where to get lye from.
  Forget the LYE...no need to go full bore on chemicals. I haven't used ANY for over 20 yrs. Just not necessary. Water is your friend

Do occasionally have an issue with the grey water backing up into the shower pan when underway on twisty roads. Grey water tank shouldn't be that full so just wondering if the run from shower to tank may have a negative incline so it's not draining fully. Shower pan drains fast otherwise. I don't think that's got anything to do with the toilet burping issue though.

Shower backing up when driving on twisty roads.......most likely a sag/dip in shower drain line to tank
You state shower drains fast when using.....check the shower drain line IF accessible. Otherwise....put a stopper over drain for traveling

[DarkSideJeep]

Originally Posted by TheCatsRV

Thank you all. Just a few more observations (and the problem is intermittent, not constant).

• Just wondering if I'm not priming the black water tank with enough water after emptying.
• Tank seems fairly small (and is pretty much right above the toilet). Plumbing isn't straight so I can't see inside. Did use the magic rinse wand (just goes around the elbow out of sight) too but I can't see down.
• Don't think it was an issue with it being too full.
• Were dry camping (usual for up here) but have read enough never to leave the black or grey water valves open even with hookups. Just flush when we go.
• I'll try the Dawn/detergent trick for the short drive to the campground and hope it works. Not sure where to get lye from.

Do occasionally have an issue with the grey water backing up into the shower pan when underway on twisty roads. Grey water tank shouldn't be that full so just wondering if the run from shower to tank may have a negative incline so it's not draining fully. Shower pan drains fast otherwise. I don't think that's got anything to do with the toilet burping issue though.

There is a mistake, always dump your tanks when preparing to leave a campsite. If your RV has Sani-flush for the black tank run some water into the black tank before you start the black tank flush. Do the black tank first then the gray tank. If there is nothing in the tank it cannot back up on you.

[TheCatsRV]

Originally Posted by Old-Biscuit

Shower backing up when driving on twisty roads.......most likely a sag/dip in shower drain line to tank
You state shower drains fast when using.....check the shower drain line IF accessible. Otherwise....put a stopper over drain for traveling

I can see the shower drain pipe but not removable (glued in good). No obvious sags but maybe there is an uphill incline to the gray water tank. It has one of those (stuck in good) grates. I will see about fitting a stopper.

[TheCatsRV]

Originally Posted by DarkSideJeep

There is a mistake, always dump your tanks when preparing to leave a campsite. If your RV has Sani-flush for the black tank run some water into the black tank before you start the black tank flush. Do the black tank first then the gray tank. If there is nothing in the tank it cannot back up on you.

We do whenever we can. Unfortunately the last time I remember we were at a remote park campground with no dump facilities of any kind. Were only there overnight since the last dump and no prodigious use of water.



I always flush as much water as possible into the black (and gray) water tank before dumping. May be hard build ups from the previous 4 owners (rig is 17 years old) though I've never let the tanks dry out. Always some antifreeze in winter.

[SafariBen]

The lye, dawn or quaternary ammonia is for the vent pipe, pour down from the roof. The toilet to tank plumbing will be 3" so won't be plugged, or you'd know it from the poor flush. I thought the shower drain might be tied to the black vent, the shower would empty into the black tank if that was the case. Shower can go into black or grey tank on different RV's.

[TheCatsRV]

Originally Posted by SafariBen

The lye, dawn or quaternary ammonia is for the vent pipe, pour down from the roof. The toilet to tank plumbing will be 3" so won't be plugged, or you'd know it from the poor flush. I thought the shower drain might be tied to the black vent, the shower would empty into the black tank if that was the case. Shower can go into black or grey tank on different RV's.

In this rig ('07 Coachmen Mirada 300QB FWIW), the shower drain and gray water vent pipe (runs up behind shower wall forward of the shower) are tied and drains forward presumably to the gray water tank which is situated between the front and rear wheels. The black water vent is aft of the shower (again behind the cubicle wall) but I cannot see where it goes (looks like under the floorboard but I cannot see it from under the chassis).



I did drop the snake down the height of the RV from ceiling to ~ floor level and felt a bend which I augered the snake to go further. Which direction I do not know.



Both tank vents are on the right side but both tanks are mounted on the left side.

[egwilly]

It would seem to me if you are able to run water into the black tank from the roof vent outlet, then the level gages shows increase, then the vent is not your issue.

Poop pyramid is most likely issue.

Best wishes for a cure.