3761 Gray Tank

[bwright]

We are on our first trip in our new 3761 which has two gray water tanks. I have had to dump the gray water tank for the kitchen sink and half bath, rarely used, twice in two days. Anyone know how big this tank is? This is not our first fifth wheel and it’s just my wife and I. We should be able to go several days without dumping that tank. Any ideas on a problem?

[DQDick]

Do you have a washing machine? Wash loads usually empty into one of the gray tanks and it won't take long to fill it up.

[bwright]

No washing machine

[rohrmann]

You have two 44 gallon grey tanks and it looks like you have two 44 gallon black tanks, so, unless you are taking long showers, I would think two or three days could fill a grey tank. Are you looking at your tank level monitor for tank levels that are saying your tanks are full? If so, they aren't very accurate.

[Carl n Susan]

That tank has to be in the 40 gallon range. Filling up each day for two days is a lot of water. I think the only fixtures that drain into it are the faucets in the kitchen and sink. I would first open the drain (close the others) with a clear plastic connector to see if there is a constant stream of water emanating. Obviously there should not be ant if the faucets are off. If there is then something else is draining and needs to be found.

If no water is running out, then the questions is how much water are you running washing dishes? A continuous stream can use a lot of water. Not that it is a real problem, many of us leave that drain valve open all the time so we don't have to worry about filling the tank.

[bwright]

So, it appears we have a clogged/blocked pipes in the sink. It is definitely not a full tank problem. As I said in my first post, brand new unit out for our first trip. If I dump the tank, it drains the sinks as well. Any ideas? I may have to pull pipes under the sink, but I don’t want to.

[RMcNeal]

If you really think it's a clog, I would try some of the Unique Digest-IT product. Saw a video not long ago where it completely disintegrated food to sludge in about 2 hours. It is a black tank additive but many seem to use sometimes in their galley tank due to food particles going down the sink. Various sizes on Amazon like this one...
https://www.amazon.com/Unique-Digest...NsaWNrPXRydWU=

[RMcNeal]

Sorry, I just re-read the posts. Is it possible the vent is clogged and not allowing air to get back into the tank? If tank is not full but sink won't drain, that may be your issue. Check the vent pipe on the roof to be sure there isn't a bird nest or small critter in there.

[Traveling Monty]

Originally Posted by bwright

We are on our first trip in our new 3761 which has two gray water tanks. I have had to dump the gray water tank for the kitchen sink and half bath, rarely used, twice in two days. Anyone know how big this tank is? This is not our first fifth wheel and it’s just my wife and I. We should be able to go several days without dumping that tank. Any ideas on a problem?

What did you ever find as the root cause?

[bwright]

No, I still have the same issue. Took it to the dealer, they said they couldn’t find a problem.

[LeftOverParts]

Couple ideas:

You could hook-up a flow meter and after the water heater fills up, zero it, then only use the kitchen faucet to get an idea of how many gallons until the sink backs up. We have one like this to use when filling the black tank with the black tank sprayer.

https://www.amazon.com/Save-a-Drop-P...38&sr=8-6&th=1

A bore scope camera that hooks up to a laptop or smart phone to push down the sink and/or into the dump to see if there are any obstructions. These things are also handy for looking behind walls, inside engine compartments, etc. You'll need to check or search for the connector type to make sure it's compatible with your laptop or phone.

https://www.amazon.com/Endoscope-Cam...s%2C157&sr=8-4