Holding tank runs slow

davelinde

Well-known member
On delivery I noticed that my kitchen grey holding tanks drains very very slowly. The PDI guy agreed and said he suspected there was construction debris in there and no way to remove it other than removing the tank (and neither of us wanted to go that route right away).

He suggested a few fill/flush and maybe backflushing to see if I could clear the debris that way. Will try that next week on our next trip.

Any other ideas? The gate valve seem to operate fine. It is slow enough to be very annoying but not so slow to be useless (yet).
 

kurt999

Member
I had the same issue with my black tank.
I built a back flush device and after 6 tp eight times out came a large piece of clear plastic. What a mess!
At least your not dealing with the black tank.
Kurt999
 

davelinde

Well-known member
...after 6 tp eight times out came a large piece of clear plastic. What a mess!
At least your not dealing with the black tank.
Kurt999

Whatever I've got... let's hope it fits to come out!!!
I agree that a black tank is worse - but the galley grey usually smells worse!

From my old rig I've got a backflush device I can use -- but with the smaller drain pipe I'm worried if I've got anything other than sawdust, metal shavings, etc in there. I cannot live with this irritation long term - but dropping the tank to fix is is not appealing either. At this point with a full galley I can open the galley, drain the black, rinse the black, drain the shower, then sit for 10 minutes while the galley finishes dribbling out... I guess that's what warranties are for -- though I'll stay optimistic I can flush out the issue in our next trip.
 

cdbMidland

Past Michigan Chapter Leader
I would hesitate to open the black tank while any grey tank is open, even if that tank was draining slowly. I think it could push black tank contents back into the grey tank.
 

tbsimmons

Member
Might check to see that that that the vent for the kitchen sink works. No vent, it will drain really slow. The vent for the tank through the roof also. Should be able to pull the top off and look down.
 

Pulltab

Well-known member
Good chance that the bottom of the tanks are not supported well and after a time of holding liquid will bow and then that is lower than the drain. I had to support all three of my tanks as I could hardly even drain the black tank after about 4 months.
 

davelinde

Well-known member
Might check to see that that that the vent for the kitchen sink works. No vent, it will drain really slow. The vent for the tank through the roof also. Should be able to pull the top off and look down.


This weekend I had a little time to experiment while dumping the tanks. I tried to backflush the tank and it made some really awful noises... So I went under the sink and pulled the vent off. Noises stopped and the tank ran normally. I'm guessing that vent is not functional and it does not look like it can be repaired. I am not sure where that tank vents to the roof.
 
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