Skip to main content ↑ ↓
Topic: Grey Tank Occurance (Read 798 times) previous topic - next topic

Grey Tank Occurance

Today, driving from Keith Risch RV Repair to Ole Cotton Gin RV Park on Hwy 287, between Decatur, TX and our campground, the gray tank decided to burb.  At the bathroom sink, we had a towel laid in the bottom of the sink with the soap bottle, cup holder and Kleenex on top of it.  When we arrived at the campground, removed the items from bath sink and removed towel, the towel was wet with dirty (gray water) ring on the towel and small amount of debris in the sink at the drain.  No indication of this "burp" at kitchen or shower drains.  Hwy 287 is famous for its whoop de doos in some areas.  I'm thinking the drain trap just sloshed water out but Joyce says she saw a piece of rice in the debris.  So it must have come from the gray tank.  In all my years of traveling in a motor home or trailer, I have never seen this happen.  Gray tank was 66% full.  Anyone ever had this happen?  Normally I do not travel with much in the black and gray tanks.  But Keith's place did not have a dump station so decided to wait until we got to tonight's campground.  Just curious.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Grey Tank Occurance

Reply #1 –
If the roof vent is blocked (think Mud Dobbers) OR if the pipe has fallen down into the tank this can happen (has to vent somewhere).
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Grey Tank Occurance

Reply #2 –
No i have not. But the very first thing i thought of was a plugged vent also. Hard to imagine but strange things do happen.

Re: Grey Tank Occurance

Reply #3 –
Thanks Brett and Scott.  I will check the vent.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Grey Tank Occurance

Reply #4 –
Your shower drain is lower than the bathroom sink. I would think that you would have had the bottom of the shower with water in it, first. What's that smell?

Re: Grey Tank Occurance

Reply #5 –
Quote from: erniee –
Your shower drain is lower than the bathroom sink. I would think that you would have had the bottom of the shower with water in it, first. What's that smell?
Im guessing it was just a weird slosh in the tank that forced fluid in that one particular drain? I think the shower doesn't share the same down pipe to the grey tank. The sink is quite higher, farther away from the tank and much more restrictive. Strange to say the least. My vent was nearly completely plugged with paper wasp nests. Wasn't causing any issues. Hopefully this is a one off fluke. Other than the vent I would speculate any other problem would be present all the time and the drain rate out of the sink would be slow do to a blockage? That sink is not directly connected to the vent directly but uses the air admittance valve to assist draining to the tank. Amazon.com: Studor 20341 Mini-Vent Air Admittance Valve with PVC Adapter,...  Air admittance valves do get old and lazy and also can become almost glued closed. Think they are a five or ten year service life. But if it was open they stink and if stuck closed don't help being a vacuum breaker P traps will be empty all the time and also stink. I'm back to it being a weird slosh in the tank and hit the drain tube. Running cascade soap in both storage tanks may help to prevent buildup and water spots. 🤷🏼
studormini-vent air admittance valve life expectancy - Google Search
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Grey Tank Occurance

Reply #6 –
I also wondered about the Shower drain.  There was no indication of a backup in the shower.  No odor of any kind, even in the bathroom sink...strange.  Drains run clear and free.  Will get on top of the coach with water hose and run water down and see if it is restricted.  Air admittance valve replaced a couple years ago and we are not having any odor issues.  Thanks for the input.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Grey Tank Occurance

Reply #7 –
Update: Vents are clear.  I believe this was a one time freaky occurrence that could have been caused by a 66% full gray tank and a bath drain that was closer to the tank than the others.  With the sloshing caused by driving and the high temperatures, I think it just burped and the bath drain was the easiest path.  The sink drain is connected to the gray tank at the opposite end (drivers side) of the vent and other drains.  I agree with your guess Scott.  Thanks everyone for your input.
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Grey Tank Occurance

Reply #8 –
When I had a Monaco with the grey water tank almost full I had the grey water slosh back into the shower
so I installed a check valve in the shower drain and that fixed the problem.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport
 

Re: Grey Tank Occurance

Reply #9 –
I must say I like your idea of having a towel covering it. If anything had been different it probably wouldn't have occurred. Couple MPH faster or slower, little more or less gray water, sun in a different position in the sky, tire pressure, something just happen. Now if it duplicates that's a different matter. If you have seen ever witnessed a fluid in motion/vibration it can do unexpected movements. My son in law could explain the theories to why this happens, but it's above my actual understanding. I just know it can happen.