My black tank keeps filling up with fresh water!

[bheckie123]

I need help! My toilet flushes fine. But after flushing and the water shuts off in the bowl, I could hear water flowing somewhere. Well after about 20 minutes we had water spilling over the toilet bowl. I quickly turned off the water at the spigot and discovered my blank tank was completely full of fresh water. If I turn the water back on, my black tank starts filling again. I thought I could use my “fresh water” tank and run my water pump, but the same things happen? Is there a valve stuck somewhere? I could you some advice please…I’ll look forward to seeing some replies.

[dhuhn]

The only other place you could get water into black tank is black tank flush, do you have your hose connected to it and not your city water connection?

[Carl n Susan]

The Thetford toilet is notorious for having a leaky water valve that continues to add water to the bowl after a flush. But you would see that and it fills the bowl not the tank.

Dan is right on. The only normal way to fill a black tank in 20 minutes is via the black tank flush. The only other way is *IF* you have a washer that is leaking water and it drains to the black tank. But that config is very unusual.

[Mikendebbie]

Just curious…is it the black tank for the half bath that is filling up ? Or the master bath black tank?

In the sketch below - A is the location of the black tank rinse backflow valve for the master bath black tank. There is an access hatch inside the lower cabinet.

B - the backflow preventer valve for the half bath black tank can be found in the rats nest of wires and pipes behind the basement bulkhead wall near the wet bay.

Listen at these locations to see if you hear water running.

In my unit - the washing machine drains to the black tank…but this can vary. The half bath potti goes to it also. The half bath sink may also go to that tank…I am not sure. I believe the kitchen sink drains to the gray tank.

The master bath potti is served by the other black tank. The sinks may also drain to the black tank…I have never tested those. Bath tub and shower definitely go to the gray tank.

[bheckie123]

Thanks for the quick replies everybody....and I'm totally embarrassed! I did have my black tank flusher hooked-up and turned on! Totally stupid of me...getting old I guess!

[Mikendebbie]

Welcome to the club!!!!!

[Ahdmeyer]

good thing you were home when that happened or it certainly would have been worse. mistakes do happen, it could have been much worse. (bet that won't happen again)!