Helping a friend with her grey water tank issues.2009 36 ft. MotorcoachThe tank drains very slowly. About 4 months ago we drained the tank as best we could and then took apart the slide valve and connecting piping to the tank, leaving the tank outlet open. Sludge came out and because we were in a campground we could not let too much drain out as other units were next door. Put things back together and filled the tank and did some direct drains and all improved quite a bit. 4 months later, now back in the same situation. This time she is in an area she can dump the grey water tank onto the ground (at a farm). TTwo questions:1) Any suggestions on how to flush the tank other than a hose directly into the tank through the exposed outlet when we take the piping apart. I am a little shy of using a pressure washer into the tank.2) How can she prevent the sludge build up. She lives the coach full time and does not put anything but dish water and shower water into the grey tank. She does not have a dishwasher or clothes washer in the coach.Any suggestions will be well received.

RTrider wrote:.. does not put anything but dish water and shower water into the grey tank. She does not have a dishwasher or clothes washer in the coach..What's in the dish water? Grease is the big problem. Have you done a close inspection of the gray water? Sounds like the tank needs a thorough cleaning.. but I don't know how that's done. I wouldn't have a problem getting a pressure wand in there as long as there's a way for air to escape. Either that or a lot of really hot water.

I would try hot water, TSP, then a High Pressure washer.

I bleach mine fairly frequently. The bleach gets rid of the odors and gunk. That might work eventually, but if it is really bad, I think I would try a septic tank treatment with enzymes.

I'm betting she leaves the gray tank valve open whens she's parked. liquids run out but solids build up. After you get it cleaned out have her leave then valve closed till the tank fills and has more liquid to flush out the sludge. Heavy treatment of Dawn dish soap drive around for a while and drain. If it takes oil off shore birds it should work on the sludge. Have her do the Dawn each time she changes parks.

John Wayne wrote:I'm betting she leaves the gray tank valve open whens she's parked..Good point, pilgrim.

Grey water tank sludge | Good Sam Community

2oldman
Explorer II
Jun 18, 2017
RTrider wrote:
.. does not put anything but dish water and shower water into the grey tank. She does not have a dishwasher or clothes washer in the coach..
What's in the dish water? Grease is the big problem. Have you done a close inspection of the gray water?

Sounds like the tank needs a thorough cleaning.. but I don't know how that's done. I wouldn't have a problem getting a pressure wand in there as long as there's a way for air to escape. Either that or a lot of really hot water.
rbrand
Explorer
Jun 18, 2017
I would try hot water, TSP, then a High Pressure washer.
JimK-NY
Explorer II
Jun 18, 2017
I bleach mine fairly frequently. The bleach gets rid of the odors and gunk. That might work eventually, but if it is really bad, I think I would try a septic tank treatment with enzymes.
John_Wayne
Explorer II
Jun 18, 2017
I'm betting she leaves the gray tank valve open whens she's parked. liquids run out but solids build up. After you get it cleaned out have her leave then valve closed till the tank fills and has more liquid to flush out the sludge. Heavy treatment of Dawn dish soap drive around for a while and drain. If it takes oil off shore birds it should work on the sludge. Have her do the Dawn each time she changes parks.
2oldman
Explorer II
Jun 18, 2017
John Wayne wrote:
I'm betting she leaves the gray tank valve open whens she's parked..
Good point, pilgrim.
SoundGuy
Explorer
Jun 18, 2017
I've used Walex Elemonate in the grey tank for a couple of years now and have no tank issues at all. :B
old_guy
Explorer
Jun 18, 2017
walex elemonate and Happy camper are two very good chemicals to use in either tank. I had a cleanout installed in both the black and the grey tanks, they kept both tanks squeaky clean
coolmom42
Explorer II
Jun 18, 2017
John Wayne wrote:
I'm betting she leaves the gray tank valve open whens she's parked. liquids run out but solids build up. After you get it cleaned out have her leave then valve closed till the tank fills and has more liquid to flush out the sludge. Heavy treatment of Dawn dish soap drive around for a while and drain. If it takes oil off shore birds it should work on the sludge. Have her do the Dawn each time she changes parks.

This.

When she is parked, she should leave the gray (and black) tank closed until it's almost full. Then dump the black, dump the gray. Both will do much better that way.

Before moving, add 2 cups Borax or Calgon water softener, and a cup of laundry detergent or Dawn dish detergent, to each tank. I would think this would work best with the tanks about half full Drive and let that slosh around for a while. Then fill the tank and dump. Repeat this every time before moving.

A lot of people add this to every tank, moving or not.
rockhillmanor
Explorer
Jun 18, 2017
2oldman wrote:
John Wayne wrote:
I'm betting she leaves the gray tank valve open whens she's parked..
Good point, pilgrim.

X3
The only way the gray tank can get sludge like that is if the valve is left open all the time. The grease and food stuffs just sit on the bottom and rot. Holding tanks need water in them for them to work properly.

Many that stay in their RV do it all the time. And many RV'ers.

Get some pinesol and pour a couple of quarts into the tank and fill with water, dump and repeat as necessary,"while you are hooked up to the sewer connction." That should clean it out and then "leave that valve closed" until full and then dump.

Which also brings up the subject does she leave the black tank open too? Cause that most likely has already created a mountain of poo waiting to clog and stink things up.

Both tanks closed and dumped when full. First Black and then gray.
gperky
Explorer
Jun 18, 2017
Use some ingenuity to find a way to keep dirty dishwater out of the gray water tank. It's the grease and solids that cause the problems. We pre-wash in a separate pan before the final dish rinse, and then dump the pan in the toilet. Our black water tank gets a regular pressure wash, so it never has any problems.