As I have posted on here ,we are having a problem with our grey water tank draining. It really takes about 35 minutes to drain the tank. I have pulled the drain pipe and washed out the tank and could find nothing plugged. The drain pipe is 1 1/2 inches in diameter. Would putting a larger diameter drain pipe help,or should I be looking somewhere else. I put a new vent cap on,but right now I'm at wits end,trying to figure this out. I don't want to put everything back together until I have exhausted all the options. gate valve works just fine. Any ideas or suggestions? Thanks to all of you.

How many gallons is the tank? I can drain my 30 gallon grey tank through a garden hose in less time than that. You may have a blocked vent.

You have a problem!40 gallons should drain in less then 10 minutes. My guess is there is something blocking the connection at the tank.

It is probably not a vent problem. If the vent was plugged it likely would siphon the water from the sinks and shower drain traps and vent that way. I have heard of cutouts from the installation process being left inside the tanks and blocking the outlet. With water in the tank you could run a plumbing snake from the drain into the tank. If the flow improves then slows again when you remove the snake that would indicate something floating against the outlet

Thanks for the answers so far. I have removed the drain pipe from the tank. I have stuck my arm up in there and felt around ( Very nasty) I have found no cut out and I used a hose to kinda wash the inside of the tank. after draining 3 bucket loads I have found nothing that would plug the outlet. Keep your suggestions coming --Thank you

3 inch grey water drain? | Good Sam Community

bartlettj
Explorer
Apr 07, 2017
How many gallons is the tank? I can drain my 30 gallon grey tank through a garden hose in less time than that. You may have a blocked vent.
1Longbow
Explorer
Apr 07, 2017
Its a 40 gallon tank
enblethen
Nomad
Apr 07, 2017
You have a problem!
40 gallons should drain in less then 10 minutes.
My guess is there is something blocking the connection at the tank.
fpresto
Explorer
Apr 07, 2017
It is probably not a vent problem. If the vent was plugged it likely would siphon the water from the sinks and shower drain traps and vent that way. I have heard of cutouts from the installation process being left inside the tanks and blocking the outlet. With water in the tank you could run a plumbing snake from the drain into the tank. If the flow improves then slows again when you remove the snake that would indicate something floating against the outlet
1Longbow
Explorer
Apr 08, 2017
Thanks for the answers so far. I have removed the drain pipe from the tank. I have stuck my arm up in there and felt around ( Very nasty) I have found no cut out and I used a hose to kinda wash the inside of the tank. after draining 3 bucket loads I have found nothing that would plug the outlet. Keep your suggestions coming --Thank you
ScottG
Nomad
Apr 08, 2017
I get a rush of fluid and then it barely trickles endlessly. Is that what your seeing?
I just drain the bulk of it in a couple of minutes and then leave the trickle part in there - couldn't be more than a couple of gallons. I can dump grey at home so I leave it open for a few hours to fully drain.
enblethen
Nomad
Apr 08, 2017
Stuck your arm in the hole? Hard to do on a 1 1/2 pipe.
Are you sure you are not in the black tank?
Grey tanks should be reasonable clean.
Make and model of rig in your signature would help on this issue and future ones. Yes, everyone will have future issues!
DutchmenSport
Explorer
Apr 08, 2017
Simple gravity? is the drain line sloped down hill enough?
camperforlife
Explorer
Apr 08, 2017
My bet is when they drilled the outlet in your tank they let the cutout blank fall in the tank and didn't retrieve it. The tank starts to drain until the blank flows to the opening and plugs it. I'd be willing to wager on it!!
1Longbow
Explorer
Apr 08, 2017
I'm in the grey tank,I remove the 3 inch connector at the tank)1 1/2inch pipe connects to this connector ,which is glued into the tank, The tank has a side mount drain and it does have a good slope to it. The tank is molded so there was no cut out,it was molded with the outlet in it. I thought it would be a cut out also,,but being molded one piece,thats not the case as I have found out. The tank had lots of soap scum on the walls of the tank,but nothing that would not plug the drain .I'm wondering now if it might be some type of vent problem. Keep them coming.Thank you