A very strange evening with water.

Fiddlinmike

While camping in my 2019 320, hooked to city water, I awoke to the sound of dripping.  I found the toilet had filled completely and was overflowing into the shower floor. I flushed the toilet and checked to make sure there was no more water coming into the toilet bowl from what I assumed had been a partially open water supply valve.  Since the water into the bowl stopped I thought the problem was resolved and went back to sleep.

In the morning we had to break camp.  I turned the city water off and started to unscrew the hose at the city water port on our camper.  It was hot!  As I disconnected the hose I had a strong stream of hot water coming out of the camper’s city water inlet that shortly died away.  I also found a completely full grey water tank AND a full black water tank, though we had barely used any water during our one-day stay.  We had no time to deal with these problems, so we dumped our tanks and headed for the next stop.

We had no water service at the next campsite so we filled the freshwater tank.  I turned on the water pump and got our first clue to the morning mystery. Water started streaming out of the city water inlet.  That told me the check valve on the city water inlet had failed, but why?  That sparked a memory providing clue number 2.  Before we left our prior campsite the camp host was circling the grounds to tell everyone that the water system was going to be down 30 minutes for maintenance.  That smelled like a high-pressure surge got us during the night - maybe affecting the check valve and even the toilet supply valve. We had a regulator (a plastic blue Camco) that I later tested and found had failed.

The check valve at the city water inlet was an easy fix.  I just popped out the little screen at the inlet and pressed the valve a couple of times to unstick it. That would prevent flow out, hot or cold.  I’m assuming the hot water that came out of the failed check valve was just a matter of pressure built up from the Alde system (the Alde was on and we were getting hot water at the faucet before all this happened).  

The full grey water tank was easy to diagnose; water dripping into the shower drain could have been going for hours.  I still don’t understand why the black water tank filled. I know the toilet release valve never opened or leaked during the night because the toilet continuously overflowed and has held water ever since.

Back at home I inspected the check valve again.  It’s holding fine. I checked the famous yellow flapper valve at the Alde and it appears to be working properly (down). I replaced the plastic pressure regulator with a brass one and hooked up to city water.  It’s been hooked for several hours and everything seems to be working fine.  

Any theories on 1.) why the black water tank filled; 2.) whether there was indeed a high pressure event that would throw open the city water check valve and the water supply valve to the toilet; and 3.) whether the hot water that came out of the city water inlet suggests more of a problem than just one check valve at the outlet?

Thanks for your thoughts!

PS.  From now on I’m going to turn my city water off anytime I’m away from the T@B, or sleeping.

Jilong

For my peace of mind, I usually fill the freshwater tank when I arrive at a campground with hookups, disconnect the city water, and only use the freshwater tank during our stay.

Mickerly

The barrel shaped "regulators," like the blue camco unit, are just restrictors and don't actually regulate pressure. Get your blue camco regulator and remove the rubber washer. Poke your finger in the opposite end and the plastic restrictor pops out. It can be cleaned and reassembled...

The 50psi device will reduce the normal 160psi to just short of 50psi. Basically a third of the pressure that goes in. If you have a surge to 200psi, the trailer will receive a third, or about 70psi. To test the unit, you need to know the input pressure as well as the output pressure. If it's about a third, then it is fine. If it is less: disassemble, clean, and reassemble.

If you want a regulator that controls the pressure, you need an adjustable regulator with a bell shaped assembly, an adjusting screw, and a gauge. Home regulators are expensive. The small ones for RV are pretty cheep.

Sharon_is_SAM

@Fiddlinmike - regarding the filled black tank, we recently found that our toilet bowl was not holding water and it required a new blade seal.  If that is leaking, then a chronic leak into the bowl would eventually fill the black tank.  But, you said your was holding water.  Hmmm. I believe the gray and black tank share a vent.  Any possibility that can contribute to a full black tank?

Fiddlinmike

@Sharon_is_SAM.  The black/grey shared vent was my theory as well.  I didn’t want to bias others so I just left it as an open question.  As I understand it, a full grey water tank will back up in the shower floor.  Mine didn’t do that.  I don’t know where the vent pipes connect, but I think it would be odd to connect below the shower floor.  If they do, that could be the source of a full black water tank.  I couldn’t find that answer on the forum.

Sharon_is_SAM

Here is a photo showing the vents.  Looks like the sink would overflow before the black tank took on water.

Fiddlinmike

@Sharon_is_SAM  Yep.  It wouldn’t make sense to design something that would allow the grey water tank to overflow to the black, and the sink drain was definitely not plugged.  My situation is still a mystery, though I think the only reasonable explanation is that somehow the toilet drain leaked.  The problem with that theory is that it would have had to correct itself when the black tank got full - not likely.  As I said, the toilet bowl was full of water and overflowing when I discovered the drip into the shower drain.  I’ve tested the toilet drain valve a few times - not a drop leaks today.  Thanks for the photo!

Horigan

The sink may not overflow if there is a Hepvo valve for the P-trap.  It's basically a check valve.

manyman297

So this may mean something or nothing at all. Back when we first got our 2021 400 I never left water in the toilet in between trips. Subsequently I started noticing sometime the water I would leave in the bowl during trips would drain into the tank (like the seals were bad). 

After doing a little research I started using thetford’s toilet gasket lubricant. You just pour a little in when the camper is not in use and it keeps the seal moist and hydrated. 

This seemed to work and I’ve been doing it ever since. Not sure if this is the issue with you but maybe your seals were dry enough to where water was slowly draining into the black tank.