Black Tank Overflow

[lifeontheroad]

So I've been having issues with my black tank since I brought it in for service a couple months ago. First, it was smelly. I used the holding tank treatments and kept an eye on the gauges to ensure it was dumped appropriately, but it would still smell. I started dumping it more frequently - maybe at about 2/3 full - and that seemed to help. This week however, things have taken a turn for the worse. My black tank is now leaking into the toilet.

1. Usually living by myself, I empty out the black tank once every 5 days or so. I am a bit cautious about overfilling it, so I try to find a good balance between letting it get too full, and not having enough water in the tank to dissolve the solids.

2. I emptied the blank tank out on 9/10/19 before my fiancee moved down. I flushed the black tank and kept the valve open for a bit to let it fully drain. I then shut the black tank valve and drained the grey tanks.

3. During the day on 9/11/19, my fiancee opened the toilet to go to the bathroom and there were solids in it. He went to flush the solids down and rather than going down to the black tank like he thought they would the toilet overflowed. He realized the reason they were in the toilet to being with was because the tank overflowed in the toilet. When he added water, the toilet overflowed.

4. I ran outside and pulled the black tank valve. It was FULL. He stayed inside and cleaned up the mess.

5. After that occurrence, we have been watching the black tank quite meticulously.

6. Yesterday (9/13) while I was at work, my fiancee emptied the black tank again. He did flushed the black tank with the valve open the whole time.

7. This morning (9/14), we woke up to find the black tank had overflowed AGAIN. There was water around the toilet, and down the wall in the back. It leaked into our basement.

We are quite puzzled why this keeps happening. Neither of us are using the bathroom enough to justify this situation. This morning, we opened the valve, flushed the tank, and then disconnected EVERYTHING from the city water. We are now using our water pump and fresh water tank for everything.

History:
1. Purchased NEW 2018 Keystone Montana 3721RL from Camper Clinic II in Buda, TX in July 2018.

2. Lived in mostly full time in Zapata, TX from July 2018 to May 2019.

3. Lived in mostly full time in San Antonio, TX from May 2019 to June 2019.

4. Took into Camper Clinic II for yearly maintenance in June 2019. Returned to same campground in San Antonio, TX after two weeks and stayed until August 2019.

5. Moved to Mathis, TX August 26, 2019 and have lived in full time since then. Only started having these issues this past week (9/10)

Anybody have any idea what could be causing this and what we can do to troubleshoot it? I don't have a truck to pull the camper, so taking it in somewhere becomes quite costly! Would prefer to try and identify on my own and then have a mobile tech come out to visit.

I also have the RV Forever Warranty. Does anybody know if they would cover this?

[speedster100]

It sounds to me like you have one of three issues, either your toilet valve is leaking water badly and the seal on the ball valve of the toilet is also leaking allowing the black tank to fill (highly unlikely).

Or your black tank valve and your grey tank valves are passing and you have a tap or something filling your Grey tnk and the water is filling both tanks..

Or someone is forgetting to shut off the water on your tank flush.

Also there is no need to hold open the toilet flush valve to assist with the black tank being emptied as both the black tank and the grey are vented to atmosphere.

The smell however does sound like you have a leaking grey or black tank valve or the tanks themselves...

The grey will smell as bad or worse than the black.

After replacing both the black & grey tank valves on our Monty due to them being stiff to pull and about a year later a bad smell was causing issues on occassion when the tanks sat for a few days while in use. I suspected a leaking tank, was under warranty and had the dealer check when it was in for other service work. They said it was a gasket, that they pressure tested the tanks to ensure they were not leaking by filling them to the top. I paid the cost of the new gaskets and the service fee for that task. The smell was still there. I took the coroplast off to check the valves etc again and neither were leaking, filled the tanks to full and low & behold the grey tank leaked like a sieve when full. After much messing around with lighting and some mirrors I found that the vent pipe had not been properly welded onto the tank from day one at the factory and one side of pipe connection had never sealed. Bought the materials to prep the tank & pipe and to properly weld the joint and fixed it myself.... No more smells........ Hope this helps

[Daryles]

Any chance you could have a pyramid? That might account for the smell and the tank filling so quickly (i.e. it never fully drains). Maybe use a USB scope and go down the toilet to see what is really going on inside.

[jimcol]

Do you have a washing machine? If so I would bet it is dumping into the black tank.

[jcurtis934]

If you have the tetford toilet, it is known to leak water out of the bowl allowing odors in, known to leak water into the bowl and overflow into the rv, known to have pedal issues. It is a piece of crap. Dometic 310 or 320 is what a lot of us have switched to. The tank is lower than the toilet by a couple of feet. If poop can migrate uphill and into the bowl when you try to flush, then you have a clogged vent and tank issues. You also could have a pyramid built up in the taking directly under where the toilet dumps into the tank caused by not using enough water when number two is done and maybe ineffective tank chemicals. Might be time to have a high pressure cleaning of the tank by a service that handles rv issues.

[beeje]

Another possibility is some thing else like a sink drain or shower drain is plumbed into the black tank. One of my previous campers had the bath sink draining into the black tank

[twindman]

I go with the pyramid problem. And if you still were filling up fast with the city water turned off, that pretty much has to be the problem.