Has anyone had an issue with black tank overflow?
Overflow back into the RV?
If that has happened without your knowledge, then likely you may have a toilet water valve leaking. That would be my guess. Replace the valve and / or the toilet. Many have traded out the Thedford for the Dometic.
Guide to Toilets (Dometic Site):
https://www.dometic.com/en-us/us/products/hygiene-and-sanitation/sanitation/rv-toilet-buying-guide
Dometic Products:
https://www.dometic.com/en-us/us/products/hygiene-and-sanitation/sanitation/toilets
Thetford Products:
https://www.thetford.com/products/toilets/rv-toilets/
Thetford Parts Breakdown:
https://www.thetford.com/part/aqua-magic-style-ii/
Parts from Amazon (42049 Kit):
If you have the Thetford, use your camera phone and turn on the flashlight. The label is on the backside near the floor. As you face the toilet, it will be on the bottom right hand side (at the floor).
You might consider ordering from this site instead of Amazon...I see there is an extra "o" ring and another part in the kit. It's cheaper as well:
http://getrvparts.com/thetford-42049-rv-style-ii-toilet-water-valve/
Thank you for the heads up on the toilet. The water is leaking below the rig, from the tank (or at least appears to be). No accidents. Just in my driveway.
Has anyone had an issue with black tank overflow?
Can you provide some additional details regarding the problem you are experiencing, as the black tank has a vent up to the roof, but no specific overflow outlet similar to the FW tank.
If the black tank is overfilled it will come up into the RV or up the vent.
Is the black water coming out of your drain valve?
Is the black water coming out from around the Corplast edge? (Black covering)
If the leak is coming out of the drain pipe, you may have a leaking valve. There are a couple of ways to handle that. One, buy another twist on valve and install it where the cap is (where you drain your tanks).
You could also take down the Corplast and change out the valve. Before doing that, flush out you tank and open/close the valve several times. Maybe there is something just stuck in the seal area.
If on the other hand you have black water leaking from out of the Corplast, it could be an indication of a tank crack. That would be the worst case scenario. The tank(s) are literally hanging from the rafter below. If you choose to travel with full tanks, that is a lot of weight hanging. Also, the tanks are cheaply made. Redwood provides no support under the bottom. The bottom will sag over time (holding liquids and solids). Eventually, they can crack or rupture. Remember that cheap made means higher profits.
It could also be a pipe joint lose from improper gluing (or no gluing). It could also just be a pipe crack.
The only way to tell for sure is to remove the Corplast and get a closer look. If the leak is slow, it could mean a crack. If the leak is fast, it could be a larger crack. If a flood happens, the tank or piping has ruptured.
Here are a couple of photos that might help. This is for a 2014 38GK. Your routing and setup may differ.
Corplast pulled down to reveal the tank location:
Corplast pulled down to reveal the valve location:
Here is how your tank sits on the support trusses:
Here is a picture of our tank that has sagged and will one day need replacing. I dare not travel with it too full:
Here is a general diagram that shows plumbing and how it is connected:
Here are a couple of shots from the 38MB...Note the area where the tanks sits on the trusses...On the MB, it apparently is much thicker (about 4") which will provide more support at this location.
On the 38GK, the photos show a much thinner area (about 2").
At least the photos imply this. I have not measured the differences...
Keep us informed of what you find.
Back to your original post...On the Black Tank, there are no overflow drains. There is the "supply" in and the vent stack out.
On the H2O tank, there is an overflow. Once you fill the tank, water will flow out onto the ground.
If you need that information, please post in the Plumbing section of this site and we can answer your concerns there.
My gosh I can not tell you how helpful this information is. I'm very new (as you can tell) I did not know the name of that layer. It is coming out of the Coraplast. When I heard the water start to come out, I looked under the rig and this layer was bulging. It is as if the tank failed in some way and spilled into that layer. The water was pouring out the opposite corner of where the main clean out valve is. I have since tilted the rig to get rid of the water under the Coraplast and dumped the tank. The leak has stopped but now I need to strip that layer back and see what has failed, broken loose, or ???. These photos are so very helpful because I did not know what to look for. Now I'm not going in there blind. I have an RV repair man ready to help on Monday, but I would like to know more going in than I do today. And... If this is a DIY gig then I will need this information. Thank you Thank you Thank you!
The coreplast is screwed into the rear of the coach and also the frames. At the edges it is simply tucked in. Above the coreplast you will find a layer of insulation.
I removed mine last Winter, as the black tank flusher was leaking. While some may be comfortable dropping the black tank to fix a valve, I am not one of them, so the coach will go to a dealer for repairs on our extended warranty.
The coreplast comes down fairly easy, but it isn't so easy putting it back.
How did you know your black tank flusher was leaking?
When flushing the black tank we had clean water coming up underneath the bathroom sink into the coach. It also ran down and puddled on the coreplast.
If it is the flushing connection, it goes into the top of the tank, which is completely inaccessible without dropping the tank - FL model.
Thank you. I did not think to look in that cabinet and will do so today.
Our black tank flushing line goes around the back of the tank then up between the tank and bottom of the floor. It then enters the coach under the bathroom sink, where they have a non-return valve, then goes down to the tank.
I believe many floorplans have a similar arrangement.
We recently had a bulging coroplast and thought we had a Black Tank problem. Started taking down the coroplast then realized the water was clear thus not from the black tank. Turned out we sprung a leak in the bottom of our Hot Water Heater and the water was draining thru a hole down into the belly.
So are you sure it's black water that's leaking?
