Blank tank is visually full after emptying yesterday

[Jim-Duffy]

Quick feedback needed:

I emptied our black tanks yesterday and got empty readings on both. I always flush until the drainage runs clear. We can go about a week before the need to empty and still usually at 2/3 on the front tank and 1/3 to 2/3 on the back tank. I prefer to drain on Friday or Saturday. Earlier this week the front black was reading 2/3 full. When I held the sensor button longer it dropped to 1/3. I'd emptied it a week ago Thursday. This past Thursday late in the date it started burping and was reading 2/3. We stopped using it (and used the back toilet) to allow time to close the gray and get it to 2/3 to clear out the drain line.

I did the normal empty yesterday, flushed as I did it to get clear drainage and got an empty reading on the sensor. Put some water back in, as usual, to add treatment. We always leave the black valve closed and the gray open when hooked up at a site. To empty, I close the grays prior to showers, empty both blacks while flushing, and use the grays to flush the sewer hoses.

Last night we noticed it was burping still (had emptied that morning). After using it a couple times during the night, we noticed this morning that the drain for the toilet is visually full - looking down the drain and seeing effluent (about 10" down below the ball valve). The sensor is reading 1/3 but if I hold it longer it drops down to empty. There is no odor inside or out and no leaks under the rig. I'm assuming a blockage between the valve and the tank and plan to put a stick or something down it but wanted feedback before doing anything.

I've searched the forum and haven't seen this specific issue. This is NOT a sensor issue - I visually see that the toilet drain below the toilet valve is full. AND, because of the sensor reading and the fact that I drained it yesterday, I also believe the tank is not full. There is no evidence the toilet valve is leaking and from reading it doesn't sound like there is any other way for water to get in there. Also, we've never used anything other than RV toilet paper.

 

[Roller4tan]

It looks like you have a "pile" at the bottom of the toilet pipe going into the tank. I know you said you flush the tank until clear, but if you only use minimal water during flush, it may not clear out the downpipe completely which eventually builds up. You can purchase a wand to connect to a garden hose to flush the pipe from the toilet. Or the vent stack is plugged.
My thoughts.

 

[Jim-Duffy]

It looks like you have a "pile" at the bottom of the toilet pipe going into the tank. I know you said you flush the tank until clear, but if you only use minimal water during flush, it may not clear out the downpipe completely which eventually builds up. You can purchase a wand to connect to a garden hose to flush the pipe from the toilet. Or the vent stack is plugged.
My thoughts.

THANKS FOR THE RESPONSE... it's appreciated.

I think you're right about a "pile". My concern about a wand is that there is very little room for additional water - about 6" or so of space between the top of the effluent in the toilet pipe to the valve/bottom of toilet bowl. I'd have to buy a wand but if I stick it down there and turn water on there isn't much room for more water.

BTW, when I said I flush until clear, I meant when emptying the black tank, I run the flush hose water until it runs clear into the exterior sewer hose (using a clear elbow, AKA Polish TV). When flushing the toilet itself we try to run plenty of water but might have gotten in a hurry, creating the "pile".

I'm guessing hooking the flush hose back up, opening the valve and running the flush won't help because it's below the pile. What about, leaving the outside valve closed and running flush water to create some air pressure. Might that help?

Final question: I can't find a diagram of the waste plumbing anywhere - the Owner's Manual or HUG. I saw a diagram on a Google search that wasn't well identified that looked like a direct drop. I stuck a blunt piece of wood down about 12-18 inches below the bottom of the bowl and hit something solid - as if the drain pipe takes a turn. Do you know how the toilet pipe is plumbed or where I can find a diagram?

 

[Roller4tan]

I don't know how a Gateway is built, but on the Bighorn you can take down the storage back wall and see all sorts of plumbing and wiring. Our toilet has a couple of 45's and short pipes to get the drain to the tank. Your pile could have built up at the bottom or around a 45 if you have any. See if you can get to the spot under the toilet from your storage. You may have to get a hand driven snake to clear the clog. I seem to remember the flush wand wasn't long enough to reach the tank on the Bighorn. If you go the snake route, be careful not to damage the tank.

 

[Jim-Duffy]

I don't know how a sundance is built, but on the Bighorn you can take down the storage back wall and see all sorts of plumbing and wiring. Our toilet has a couple of 45's and short pipes to get the drain to the tank. Your pile could have built up at the bottom or around a 45 if you have any. See if you can get to the spot under the toilet from your storage. You may have to get a hand driven snake to clear the clog. I seem to remember the flush wand wasn't long enough to reach the tank on the Bighorn. If you go the snake route, be careful not to damage the tank.

Again, THANKS for the reply!

On our Gateway, the back wall is too "buttoned up" to tear it apart to see the plumbing. I agree about a snake. We were just talking about it.

I just ran clean out flush water from the hose to add water to the tank to create a little upward air pressure and not even a bubble from the toilet view. The sensor is reading empty, which is expected considering when we emptied. My next test is to close the grays, take a shower, add more water via the flush hose and do a big swish of a drain dump to see if back pressure can help at all. THEN, we'll buy a snake while out running errands today. Always thankful to have a 2nd bathroom!!! Of course, we are in a park so all would not have been lost - just spoiled with our own facilities.

Knock on wood, we've had very few issues and none major. We've been living full-time since February. In the middle of the Northern CA redwoods... life is good.

 

[JohnDar]

If you can actually see the logjam, try pushing a stick through it and then use a hose wand to start eroding it. Don't know how you could jam up the pipe like that unless it has a P-trap in it. Mine is an almost straight drop with only an angled elbow in it.


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[Gaffer]

A snake may not work very well. I had his problem once and the resident tech used a 4 ft piece of 3/4 non metallic liquid tight flexible conduit. Big enough to move the pile and flexible enough to get there.

 

[BobTheBuilder]

We used to live aboard sailboats and the tanks are much more difficult to empty than on RVs. We never put anything in the toilet we had not eaten first. We practice this in our big horn and we never have any clogs of any kind. Keep a small trash can with the lid close by for paper.

 

[Jim-Duffy]

Thanks All! Here's the outcome.

Researched clogged vent stack and decided that wasn't it.

Purchased a hand crank 10' snake and slowly got nearly all of it down the toilet drain with very little effect. After a lot of cranking, and in-and-out-action, the effluent level drained a few inches. Poured a bucket of water in and didn't really help - had to do more snaking to get it back down to where it was but since the level was dropping a bit figured we were on the right track. Got hot and sweaty and had to take a break, during which it drained all the way! Put two buckets of hot water down and both whooshed right down. We're now at about 1/3 tank resulting from the added water and original effluent. I'm going to let it sit for a few days to let the treatment enzymes do their work to break down any clumps before draining it... also want it fuller for it to drain better. I always use the black water flush until the effluent runs clear (the clear elbows are great investments) and will do that for sure.

The Cause: we were trying to delay dumping one more day... was at 2/3 but not reading full, but was burping. I, stupidly, tried to economize on water and shouldn't have. Lesson learned - always use a healthy amount of water when flushing.

It was such a relief that we celebrated with margaritas!

 

[JohnDar]

I listen to the sound of the flush when it's been a few days since dumping. The sound deepens before it actually burps. But, the again, I've had to go out and dump at zero-dark thirty in the rain when I got lazy. ☹️


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