Grey Tank Overflow?

Ran into an interesting problem that I am hoping someone else has seen ...

Ran the dishwasher yesterday and water was coming out of a small discharge hose under the bus in the tank area. I assumed that I did not check the grey water tank level and just overflowed the tank and this hose was the overflow or something.

So today with an empty grey water tank, I took a shower then ran the dishwasher. Mid cycle the water was coming out the the discharge tube again. For grins I opened the grey water valve and the water quit dripping from the tube and the dish washer finished with no more water.

Showers, sinks, etc. do not appear to cause the discharge. Have not tried the washing machine yet.

Any thoughts would be great.

I've filled my grey tank several ways (shower, kitchen sink, bathroom sink), but never had it overflow on the ground. Mine simply starts to gurgle which causes my wife to gurgle (nice word for it) which causes me to run out and dump the tank.
But perhaps CC built their tank with an overflow, i doubt it.
I more suspect there's something wrong with your drain lines that go from your dishwasher to the tank.
Maybe there's an overflow link only on the dishwasher line going to the tank.

Mark, My CC is a 2002 and does not have an overflow on the grey tank. The dishwasher does have a separate vent to the roof. Perhaps yours has a hose for the vent or was modified in the past if the original vent had some problem. It is very hard to reach on my coach. I think Joe is on the right track and would check the dish washer lines.

It seems to me that a grey tank will have a vent... might not be called an overflow but when draining the tank, the tank will have to have a way to vent... allow air to enter the tank. Since most things that drain to the tank will have a P-trap, the replacement air has to come from somewhere. ???

Thanks guys, I will look at it more. Interesting though that it does not appear to have any issues as long as the grey water dump valve is open.

My 99CC did not have an over flow on it.
several times I would forget to Czech the tank before showering and would back water up in the shower.
one way to check for plumbing leaks LOL
It did have an over flow when filling the tank through the manual hose connection in the plumbing bay.

Les,
You are right, there is a vent pipe. This is required to let air out of the tank as it fills and let air into the tank as it empties. This pipe goes to the roof. My experience is that if the tank is overfilled, the water starts coming up into the shower, which is the lowest drain in the coach.

Update ... after looking at some piping diagrams that I have and some from Texas40, it would appear that the two tubes that were discharging water were possibly the two overflow points from the top rear of the fresh water tank. The tank was full. On this trip, we only had the fresh water tank 3/4 full and we have run the dishwasher once with no problems. Not sure how the dish washer would affect the fresh water tank while connected to city water. Hopefully we will get more clues in the future. In the mean time as Joe would day ... "aint this fun" ... and we are certainly having fun. Hiking in the woods and trail burgers and s'mores last night with the grandsons.

On mine, The dishwasher and Washing machine pans have drains also. These tubes act like Air conditioner drains and drop down under the bus. Make sure the dishwasher is not leaking.

Mark grey water stinks real bad after u hold it for a very short time. Because of this phenomenon they vent them through the roof like a holding tank

Yes there r bypass for them but the stream is not smelly when its fresh. I'd be really surprised to find a grey tank with an overflow because of this. The oders would be awful. Ya wanna be like the Grizwalls?

If your AutoFill valve is not closing correctly, i could see how your fresh tank could get overfull and then who knows what. On mine there is an overflow tube coming out of the manual fill tube, which is also where the autofill line dumps into the manual fill tube. But for that overflow tube to flow over, the tank level would have to be several feet above the top of the fresh tank. Which is almost the level of the dishwasher.

Thanks Joe, you may be on to something here. All of this is behind a panel that also has the outside faucet, pressure guage etc. So getting the access panel off is a bit of a project. I will add this to the list!