Question about toilet backflow


New Member
Hey all - I have a '89 minnie winnie class C that I just bought. Question..While sanitizing fresh water tank, I had to use the water pump to push water through system and into grey tank because of no drain or spicot that I could find. Before I started, all tanks were empty - it had been winterized. After pumping all the fresh into the gray via the pump, I noticed that the toilet was filled to the rim and almost overflowed. Gray water tank valve was open and tank was not allowed to fill. It just simply ran out as fast as it came in. Is there a backflow valve or something on these things that could be inop or is this normal? Est. pump run time was about 10 min. When I have constant pressure via the city water hookup, will I have to worry about water damage in the worst way? BTW, my black tank now says that its 3/4 full. Does anyone know how this happened?



New Member
RE: Question about toilet backflow

BTW, it was not black water overflow. It was auto filling without pushing the foot switch. After I finished pumping and I realized that the toilet was about to overflow, I released that water (clear with bleach smell) into the black tank via the foot pedel. I left with everything turned off (pump, elec, etc) and when I returned, the toilet was 1/2 full.


Senior Member
Re: Question about toilet backflow

There is only one valve between water pressure and the toilet bowl. It is the one controlled by your foot. It must be leaking or have something stuck in it in such a way that it won't completely close.