Black Water Leaking to Gray Water

[Dee08802]

Has anyone observed water running into the gray water tank from the black water tank. I was flushing both tanks today. I first filled the gray water tank by running water into the shower drain. When full to the top I then filled the black water tank through the toilet. When the tank got close to full I noticed water backing up through the open shower drain. Both drain valves were closed with the drain cap off and neither valve leaked. I am wondering if there is a common vent that allows black water to back up into the gray water.

[strawbarry]

Relatively sure both tanks are vented to the top of the trailer, otherwise water would not go in and out of the tanks. I have overfilled the black tank before by accident and water came down the side of the trailer.

[PM15283]

I had the black water shutoff creep open while traveling, giving quite a surprise when I wanted to connect the drain hose!
If both shutoffs were open a little and the drain cap was on tight....seems backup could occur.

[cpaharley2008]

I would fill the grey tanks via the sink, not the shower floor. The vent may have prevented filling it up 100%

[Jim Bennett]

Except for at the disposal end, the grey and black systems are separate. Both have separate vents.

[padlin]

Could you see something other then the shower pan filling to indicate it was black water? Could it have just been the grey expanding or some such?

[Dee08802]

Thanks for the responses. For clarification the cap was off the drain connection and nothing was leaking out there. What bubbled up in the shower was definitely not clean water. Tomorrow I will try refilling the black tank with the gray drain valve open to see if anything flows out. I will update then.

Ken

[gbaglo]

What's the purpose of this exercise?

[Dee08802]

I don't want black water in the gray water tank as I sometimes dump the gray on the ground at home.

[Fox hunt]

i don't see how the black tank can drain into the grey tank i don't think they are connected. .

[cpaharley2008]

You need to have your grey tank filled if you have anything in your black tank. The grey tank contents is what cleans out the hose after dumping the black tank. Without anything in your grey you can not dump.

[Donna D.]

Originally Posted by cpaharley2008

You need to have your grey tank filled if you have anything in your black tank. The grey tank contents is what cleans out the hose after dumping the black tank. Without anything in your grey you can not dump.

Sure you can, by adding more water to the black tank. I add about six gallons of 'fresh' water to the black tank after dumping both the black and then the gray and then the black again. Works for me. YMMV.

[cpaharley2008]

But that wastes water, if you dump the grey after the black, no waste.

[Donna D.]

Originally Posted by cpaharley2008

But that wastes water, if you dump the grey after the black, no waste.

I was only answering your statement "Without anything in your grey you can not dump." I typically dump at the storage yard. The water there is 'non-potable' not to be used as fresh drinking water. People use it to clean out their black tanks with hoses. I would imagine the same thing is done at the park dump station.

[jumboscott]

Since your on the subject of Black Water, my new trailer leaked 1/2 cup of black water each time between dumping on the way home from ETI. Noticed it when pulling the sewer cap off. I read a small amount of leakage is normal but anything more than a cup and you’ve got a leaky gate valve. I never had any leakage with my Casita.

[cpaharley2008]

I understand and I was referring to the comment about dumping the grey tank at home. That seems illogical because of the black tank issue. Your work around can work but using the KISS works also with less waste. What is the saying "more than one way to......"

[gbaglo]

If I understand you Jim, you are saying that if you dump your grey tank at home, you won't have water available to flush the sani hose after dumping your black tank.
I don't understand why one would save the grey water to dump at home.
In any event, my black tank always fills up before the grey tank and I always dump both at a sani-dump, first the black and then the grey, to flush the hose.
I've never had more than a couple drops of liquid after closing the traps.

[rubicon327]

Originally Posted by jumboscott

Since your on the subject of Black Water, my new trailer leaked 1/2 cup of black water each time between dumping on the way home from ETI. Noticed it when pulling the sewer cap off. I read a small amount of leakage is normal but anything more than a cup and you’ve got a leaky gate valve. I never had any leakage with my Casita.

Personally I think any blackwater leaking by indicates a valve that is is need of attention. Try spraying some freshwater up into the outlet with the gate valve partially open. Maybe there is some gunk on it. With black tank already empty of course! In the meantime something like this might be handy....three-fold advantage...clear to see if any waste leaked by, a cheater drain to bleed anything off into a container that could be returned to tank via toilet, and a handle to keep your hand off the rim where it mates up. Brilliant, right?!

http://www.etrailer.com/Accessories-...hoCjiMQAvD_BwE

[cpaharley2008]

Not me Glenn, post#9 referred to doing it at home. I was responding to that comment.

[gbaglo]

Originally Posted by cpaharley2008

Not me Glenn, post#9 referred to doing it at home. I was responding to that comment.

I know.