Slow Grey Water Drain

[NorCal C&H]

I have read the 2008 and other posts about this subject but believe this is new information.

Like many of you have reported, my black water tank dumps fine but the grey water starts off OK then soon slows to a small stream that goes on for what seems like hours to completely drain.

Since, from the ground, I can only see one tank vent on the roof I opened the passenger side access door below the roof vent to get to the grey and black tanks. I can see where the toilet dumps into the black water tank and what appears to be a vent pipe on each of the tanks but when I open the inside drawers in the compartment just behind the refrigerator (where the washer and dryer would go) I see what I thought might have been the grey water vent is in fact the drain pipe, including trap, for the washing machine.

So, unless WRV installed the grey water tank vent on the drivers side of the coach, I don't think they installed one.

Harold

[Old Scout]

Think you will find two vents on top of yr rig--one for grey and one for black.....yet slow moving grey water remains a mystery for many of us....

[F&D ABQ]

On my '01 34-footer, which is plumbed for a W/D (nice to have if one doesn't need any clothes drawers at all), the waste line has both a standpipe (which is capped in my case) and a valved vent. BTW, I haven't noticed a problem with slow draining.

[Barbaraok]

On our gray tank we get a slow down about half way through dumping, followed by a swoosh sound and then the rest of the tank runs out fairly quickly.

Yes, there are two vents. Putting rotating vanes was one of the best things we did - especially for the grey tank.

Barb

[Theberrys]

My washer vent had one of these installed it didn’t go to the roof.
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=Oatey+Abs+In-Line+Vent+39012&x=14&y=23
I also had slow grey water draining. After replacing the In Line Vent things got much better. I seemed the rubber one check valve in the old one was stuck and didn't allow air to be sucked into the drain.
Dick

[zinom]

Harold, The grey tank vent is on the drivers side. On my '05 36mdds it comes throught the roof just forward of the shower skylight. Matt

[NorCal C&H]

OK, thanks guys. I did the hated "duck walk" and dug the telescoping ladder out and confirmed the second roof vent ahead of the shower dome.

Now I am wondering if the grey water vent placement isn't the problem. Although I couldn't see where the vent pipe connects to the grey water tank judging by its placement on the roof I would assume it connects closer to the drain valves than the black water whose vent is in the passenger side end of the tank, the opposite end from the drain valves.

I am going to look for two self taping hose fittings. One I will tap into the washing machine clean out stand pipe behind the drawers and the second I'll put in the black water vent pipe which is about 10" away. I will then connect the two fittings with a short length of rubber hose. As long as I get an air tight fitting I shouldn't get any odor in the coach and it will provide an air vent on the BACKSIDE of the grey water tank.

Maybe I can solve another of life's great mysteries. I'll post the results.

Harold

[EngineerMike]

Harold- hose washers are notoriously leaky. IIWMI'd go to a good plumbing supply joint (i.e. not HD or Lowes) and if they have them to fit the standpipe, get two live tap fittings. These have a wrap-around section (some are mechanical and some glue on) that cradles the existing pipe, then w/a hole saw you drill out the connection hole thru the threaded "fitting" hole. Once you have two new fitting holes installed, just connect the two w/the req'd series of PVC or ABS fittings. PVC and ABS are more reliable for the type of connection you are attempting IMO. Just a thought...

[dgerstel]

Harold,

I can not see how any problem would be created by which end of the tank the vent pipe is placed, unless the tank is REAL full and the coach is parked at an angle. My bet would be on something in the tank, blocking the flow after it partially empties. If you feel it would help to join the two tank's vents, here is a photo of a connection I made into the black tank vent.

I drilled and tapped 1/2" pipe threads into the vent thru the adapter and the pipe, to allow for a deeper connection in the pipe.

[Theberrys]

Dale

I like that foam shock absorber Now that will "Get-er-done"

Dick

[NorCal C&H]

Dale, I have to agree that the location of the vent in the tank should not have THAT MUCH impact as long as the vent enters the tank at, or near, the top of the tank.

I understand the problem with things left in the tank. While a quality assurance representative at Lockheed we had an S-3A Viking ASW aircraft wing arrive from LTV. When they lifted the wing off the flatbed truck we heard a "clunk". Opening inspection ports to investigate we discovered a kneeling pad, flashlight and rivet bucking bar. I hinted that we might want to open more ports and check for the employee.

If the vent or drain cutout plugs or other debris was left in the tank short of removing and cutting a hole in the tank does anyone have any ideas on how one would check for and remove items?

What was the purpose of your added fittings, Dale? Is that a second flush access?

Harold

[two sailors]

You could probably find a local company that does sewer pipe inspections and they
could feed a camera into the tank and have a look around.

[NorCal C&H]

EM; I wasn't thinking of using a garden hose. I was thinking of NPT to barbed brass fittings and hose / tubing with hose clamps, but after Dale and other comments I went out and removed the access panel behind the dump valves. On the left I could see the grey tank (G.T.) vent on the top of the standing leg of the "L" shaped tank.

Sooooo, I now have to agree that improper venting is looking less likely the problem. I also noticed that the G.T. drain looks like it could be removed from the end of the G.T. without too much trouble. Once I get to location where I can have better access and have good water drainage I think I will removed the fiberglass(?) panel in the back of the drain / service center then dissassemble the G.T. drain valve itself then remove the drain pipe from the tank. Then by using the tank flush system and hoses try getting enough water into the tank to flush whatever might be in there over to the drain hole. It looks like a short neck on the tank for the drain and I should be able to grab any debris with long neck pliers and cut as necessary to remove it from the tank.

Comments? Thoughts? Suggestions?

Harold

[dgerstel]

Harold,

That connection is used to pump water from the gray tank to the black, for extended stays w/o dump at the site.

Since my coach tanks and drains are different than yours, I can't go out and look at how to access the tank from the drain. After looking at the photo below, I would guess that the easiest way would be to unbolt the 2 slide valves (with tanks empty) and use some sort of hook on a flexible shaft to fish around in the tank.