Grey water tank won't drain

[rowemi]

Could you get a small, rigid kiddie swimming pool to contain the drainage. Get the snake to get it flowing with the pool placed to collect the mess. You will still have to get rid of the stuff in the pool, but at least it will be contained.

[Joenissan]

Make sure you don’t have a second gray water valve. You may have a second tank.

[Bayoutalker]

If you have to get into the underbelly don't cut the material. The panels are usually only held in place by a few screws. I removed mine and the entire panel came off in a few minutes. Much easier to put it back than trying to patch a hole you cut into it.

[hawksaway]

Originally Posted by RonM

Long story short, the grey water tank won't drain. I don't feel any difference in the valve and I can get a few galleons out of a full tank, down to the 2/3 full indicator light but then it stops flowing. I tried the liquid dishwasher soap trick this morning with 5 galleons of hot water using the kitchen sink thinking it was just a clogged sensor. I measured the amount of hot water I put in so I could determine (best guess) how much I got out. First indication something was wrong was the full light indicator coming on. If it was just a stuck sensor then 5 gals of water wouldn't ground the "full" sensor so it should have stayed at 2/3 but it didn't. 2nd bad indicator was grey water leaking out the bottom of the trailer onto my driveway. I drove 40+ miles to Camp Pendleton and dumped the grey tank expecting to get a rush of water...I didn't. I checked the indicator lights and it's back to 2/3.

We're very careful about what goes down the drain but checking other RV sites people say this happens to them all the time..news to me. I'm thinking a clogged vent or just normal accumulation over 2 years but how do I find the actual problem and then fix it? We've got another 5 weeks coming up so I gotta get this fixed!

Thanks for your help
Ron

Don’t know if this will be of any help but I learned a long time ago that filling my black and/or gray tanks with ice cubes then driving around acted nicely to clear any clogs in those tanks. Those ice cubes acted a natural scouring agent. And when the ice cubes melted and I drained the tanks, it was always surprising to see what kind of crud canoe out.
Good luck.

[RonM]

Thanks to all that have offered suggestions and recommendation on this thread. Here's where I stand today. The Grey tank is now empty and everything is put back together but I still don't have a definitive answer.

If you’ve read this entire thread then you know I had two problems. First, I had several indications that the grey water tank might actually be 2/3 full and 2nd, I had water leaking from under the trailer and no idea where it was coming from.

1. I drained the grey tank into my caddy until the flow stopped.
2. With the indicator light still showing 2/3full, I put 20 gal of fresh water into the grey tank trying to make it back up into the shower or start leaking out the bottom. Nothing happened so the tank could not have been 2/3 full.
3. I drained the tank again until the flow stopped.
4. I ran the camera all way to the open grey tank, hoping all the while that if it was a blocked opening the camera wouldn’t dislodge everything before I was ready. I was really happy to find an empty take with no debris anywhere in sight so part one of the problem was just a stuck sensor or that small black disc is still sitting on the floor of my tank and I just can’t see it.

Part two of my problem is also still unanswered as well, i.e., where did the water come from that was draining onto my driveway when all this started. The obvious next step is to put 32.5 gal of water into the tank and see what happens which I’m going to do next…next hour, next day or maybe next month but it’s next on the list.

I can tell you that the amount of debris that came out of the grey tank really surprised me considering there’s just two of us and we’re pretty careful about what goes down the sink. I guess we’re just not careful enough. I’m sure the dishwashing liquid dissolved a lot of the “film” that builds on the sides of the tank. I drained the tank three times including the last one with 20 gals of fresh water and I was still getting some debris floating in the water.
I’ll let you know when I get around to “Next” .

[Route 66 Traveler]

Thanks for the update...


My grey tank started showing 1/3 full even though I knew it was empty. I tried all sorts of gimmicks to clean the sensor. I figured it was probably covered with soap scum or something similar.

I finally found Tank Blaster from Thetford. I put two packets into my 35 gallon grey tank and let it sit for about 30 hours, then drained the tank and refilled it with clean water, and drained it again. The tank is now showing Empty. Guess the stuff really works!

Tank Blaster

[turtle032]

Are you sure the level sensor is working properly? Those things are notoriously inaccurate. When you say you got a “few” gallons out are you draining it into something and measuring?

[Bayoutalker]

I never trust the tank sensor. In fact I never check it. They are notorious for being inaccurate or actually not working at all. I've never had one work properly in 5 units that I have owned. If you think it is not emptying, measure the water when filling and then draining. That will eliminate all question.

[RonM]

No it was completely unexpected and I didn't catch anything. I had put the dish washing detergent and five gal of hot water into the grey system via the kitchen sink and connected the trailer to my car. I was retracting the stab jacks from the back of the trailer and it all came rushing out from under the trailer near the main sewer drain but under the barrier so I couldn't see where it was coming from.

[RonM]

The first opportunity I had to add a specific amount of water going into the system and then measure the amount of water coming out was yesterday when I put 20 gals in and got 20 gals out. But that's a relative number and doesn't take into consideration what amount of water might have been in the tank to start with. That's why I got the camera/ The only way to know if the tank was actually empty was to look inside.

[Johnynorthland]

I had same issue with my first RV as slowpoke. The idiots at the factory drilled out and let the plug fall in the tank! Luckily I use clear connections on each ends of my sewer hose and pay careful attention when I dump my tanks! The plug got caught in my line I was lucky.

Sometimes you got to bite the bullet and just do the one thing you are avoiding, drop the tank out, remove the valve and inspect everything. Maybe even replace the tank if necessary.

Let us know what your fix was. Hopefully you will resolve it soon. Good luck

[RonM]

You're absolutely right about that. This morning I'm doing the "next" step which is filling the grey tank with 35 gals of water to see if it leaks or backs up into the shower. I really don't want to do this test but if it's leaking it's not going to fix itself.

[RonM]

I finished the last test on the grey water system this morning by putting 32.5 gals of water into the tank and there were no leaks. I filled it to the point I had standing water in the shower pan and outside everything was dry so I called it good, drained the tank and packed everything up.

I feel pretty strongly that the plastic disc is sitting on the bottom of my tank and I'm sure I'll be dealing with it again at some point but I have more tools to work with and a much better understanding of how everything works. Best part is I did it all without spending $200. an hour on labor and getting the exact same results! Thanks to everyone for you suggestions and recommendations along the way. Ron