new member with a question

[Steve78Avion]

Hello y'all. I recently bought a 1978 28M (8.5 metres). It had been used as an apartment the last seven years. As I get it up to speed for camping I am having a problem with the gray water tank not holding much more than a gallon or so before it backs up. When I open the drain valve it drains fine. I used liquid fire drain cleaner, diluted, but it did not solve my issue. I also used the black water tank cleaner and deodorizer and let it sit for a couple of days. Nothing has worked, so far. I am not sure what my next course of action it. Any advice would be appreciated. Thank you. Steve

[KYAvion]

Congrats on the new Avion. As far as the grey tank backing up, does it do this when water is poured down the kitchen sink, bath sink, or tub?

Also, can you be more specific about what happens when the grey tank backs up. For example, does the tub begin to fill with water?

[Steve78Avion]

We are very pleased with our Avion. And I am impressed with the build quality. As to the gray water tank, I have the shower with seat and the first sign of backing up is at the shower drain. I accessed the opening to the tank plumbing at the panel next to the rear of the refrigerator. I had my wife run the water at the galley sink and I listened while it ran into the gray tank. After roughly a gallon of water I heard it begin backing up the pipe, as if the tank was full. I opened the drain valve and it drained right out. This is where I am at.

[KYAvion]

That’s too bad about the clog. Are you able to access any of the plumbing fittings from the panel?

Sounds like you may need to disconnect the trap and run a snake through there.

Another option is to open the grey valve and use a hose bladder. If going this route, connect a shutoff just before the bladder so you have control of the water just in case you need to shut it off quickly.

I had a bad clog in a basement drain once. I tried drano, ran a snake, etc., and nothing worked. The hose bladder took care of it in no time at all. If you use one, bypass the trap so you can go straight into the pipe with the bladder. Make sure your grey valve is OPEN. With the bladder fully inserted into the pipe, open the water ALL the way at once so the bladder can expand and seal off the pipe.

https://www.lowes.com/pd/Cobra-Rubber-B ... lsrc=aw.ds

[KYAvion]

Something else you could try first is taking a garden hose and try running water down the vent on the roof.

[Steve78Avion]

I truly appreciate this advice. I am going to try the hose through the vent this evening. If that doesn’t work I will try the bladder. Thank you and I will update.

[KYAvion]

I’d probably try that first as well. It’d probably be a good idea to plug up the tub, bath sink, and kitchen sink drains, or at the very least have someone keeping an eye on them in case the clog diverts the water to them.

[Steve78Avion]

That’s right. Good thinking. Thank you