Gray water odor

[JGallagher]

Good Morning,

While showering, a horrible odor filled the rv. We were level, weather and wind was calm and the gray water tank was approximately 1/2 full.
The shower drain seemed to be working fine and the sinks also drain well.
I had the fan running in the bathroom.

Once we drove away, the smell dissipated and did not reappear but man, did the gray water stink when I dumped!

So, the question is: Is this a "one time" event or a sign of things to come?

I'm not sure how to check to see if the vent pipe is correctly connected or possibly blocked, so I would appreciate some guidance if you think that could be an issue.


Thank you.

[Pete'sMH]

Bummer! Might be a one time thing so I wouldn’t get very alarmed until it happens again. Check the air admittance valve under the sink. Easy to check and easy and cheap to replace if it’s stick - they just screw on. Won’t help the root problem but in hot weather we put toilet chemicals in the gray tank too to help hold down stink. Good luck!

[cavie]

Gray water often smells as bad as black

[Bob Denman]

I agree...
Add some chemicals to that tank also!

[OldWEB]

Try to determine where the smell comes from first. Ensure the toilet is sealed, and each sink is plugged tightly. If the bathroom fan is running and the smell is presumably coming from there, why would the rest of the RV get it?

The vents on the roof are easy to check if they work - sniff test.

[JGallagher]

Thanks all for the suggestions.
I'm due to get on the roof to clean it in the next couple of days so I will examine the vents then.
Interestingly, the August issue of "Motorhome" hit my mailbox yesterday and the Letters section is all about sewer odors.


I'll report back soon.

[Sweetbriar]

With a ceiling fan on exhausting air and the coach closed up if could have pulled air from the shower drain as water push thru the trap which would come from the gray tank. Gray water can get pretty foul in the summer heat. Next time try cracking a window open if you use the fan.

If the fan was supplying air from the outside than the increasing water level in the gray tank from the shower will push foul air out the roof vent that the fan could have pull into the coach. Best to keep the bathroom fan on exhaust if the tank vents are close by.

[Bob Denman]

Originally Posted by JGallagher

...Interestingly, the August issue of "Motorhome" hit my mailbox yesterday and the Letters section is all about sewer odors.
I'll report back soon.

https://www.thorforums.com/forums/at...1&d=1594231723

[Yvonnemarc]

I leave my gray water valve open to the septic. The p-traps prevent any stink from coming into the RV. The black tank valve I leave closed and empty when needed.

[GTM41261]

It also doesn't hurt to dump some PineSol into both the grey and black tanks from time to time.

[Travelin' Texans]

Originally Posted by GTM41261

It also doesn't hurt to dump some PineSol into both the grey and black tanks from time to time.

I don't recommend the Pine Sol in the black tank, it smells like you've eating pine cones, basically pine smelling crap, makes an unpleasant job worse!
BTDT with the Pine Sol, won't do it again.

[Travelin' Texans]

Originally Posted by Yvonnemarc

I leave my gray water valve open to the septic. The p-traps prevent any stink from coming into the RV. The black tank valve I leave closed and empty when needed.

If you drop a sag in your sewer hose it creates a P trap to prevent anything coming into the rv also..
And a reminder for those that may not know, NEVER EVER leave the black tank valve open, drain as needed ONLY!

[twovillagers]

Originally Posted by JGallagher

Good Morning,

While showering, a horrible odor filled the rv. We were level, weather and wind was calm and the gray water tank was approximately 1/2 full.
The shower drain seemed to be working fine and the sinks also drain well.
I had the fan running in the bathroom.

Once we drove away, the smell dissipated and did not reappear but man, did the gray water stink when I dumped!

So, the question is: Is this a "one time" event or a sign of things to come?

I'm not sure how to check to see if the vent pipe is correctly connected or possibly blocked, so I would appreciate some guidance if you think that could be an issue.




Thank you.

I cut open a pouch of the orange scented black water tank granules and wash them down the kitchen sink-just ocasionally.

[KBlanchard]

With the shower and bathroom sink dumping into the black tank, you might be experiencing the smell from the black tank. What was you black tank level?

[CaptnJohn]

Try without the fan on. You are drawing from somewhere. Turn the fan on after the showers and see if any odor.

[rottendan]

Was it a rotten egg or sewage older?

[Herbert]

Originally Posted by JGallagher

Good Morning,

While showering, a horrible odor filled the rv. We were level, weather and wind was calm and the gray water tank was approximately 1/2 full.
The shower drain seemed to be working fine and the sinks also drain well.
I had the fan running in the bathroom.

Once we drove away, the smell dissipated and did not reappear but man, did the gray water stink when I dumped!

So, the question is: Is this a "one time" event or a sign of things to come?

I'm not sure how to check to see if the vent pipe is correctly connected or possibly blocked, so I would appreciate some guidance if you think that could be an issue.


Thank you.

we are careful to clean food off of plates before doing dishes, and never pour any liquids down sink other than water and soap. Have never had odors.

[JamieGeek]

Originally Posted by KBlanchard

With the shower and bathroom sink dumping into the black tank, you might be experiencing the smell from the black tank. What was you black tank level?

Typically on Thors the shower does not drain into the black tank. Just the bathroom sink does.

[kleentank]

Great discussion, folks. It's a common problem with most RVs -- not just Thor motor coaches. We've encountered it plenty of times with our cleaning service. Here's a recent article we wrote about this issue and some solutions: Why Does My RV's Gray Tank Stink?

It's a common problem for all RVs, not just Thor motor coaches. Here's a recent article that goes over some causes as well as solutions. Some of the issues brought up here (vents, seals, traps) are valid, but the likely biggest cause is mold in your gray tank (and DO LEAVE THOSE PULLS CLOSED until you're ready to empty the tanks).

[hikerjohn7]

Originally Posted by JGallagher

Good Morning,

While showering, a horrible odor filled the rv. We were level, weather and wind was calm and the gray water tank was approximately 1/2 full.
The shower drain seemed to be working fine and the sinks also drain well.
I had the fan running in the bathroom.

Once we drove away, the smell dissipated and did not reappear but man, did the gray water stink when I dumped!

So, the question is: Is this a "one time" event or a sign of things to come?

I'm not sure how to check to see if the vent pipe is correctly connected or possibly blocked, so I would appreciate some guidance if you think that could be an issue.


Thank you.

A similar incident happened with our Class A when we took a walk on a warm day and I did not have the AC on. When we came back it was warm in the RV and it smelled terrible. We ran water down the kitchen sink and I poured gray water odor treatment down the drain and the smell went away and has not come back.

And once I drained a small amount of gray water into my yard when I had the RV at home and, you are right, it smelled as bad as black water.

What I do these days is try to limit as much as possible allowing food scraps and sauces from cooking to go down the kitchen sink drain. We carefully scrape all the scraps into the garbage and when I end up with a platter of cooking juices to throw out, I walk outside to the faucet and rinse the platter juices into the ground. Then we wash the platter.

I also regularly use gray water odor treatments (various types) particularly when I store the RV.

Something else I do, and you might do this too, is that... on the last day at a park, I close the gray water valve for the last one or two showers so that it builds up a volume of warm, soap water in the gray water tank. I use this water to flush out the swage line after I drain and flush the black water tank. I think this practice also helps clean out any food left in the gray water tank.