Gray Tank Smell (Seriously annoying)

[Wulrich]

I love our travel trailer, but we have been having some serious issues with a very potent smell.

Issue: Every time we run the kitchen faucet we get a rotten egg smell out of both of our A/C units almost instantly. We’ve had the unit for about 3 months, and this has been going on for about 2 months.

Things I’ve tried:

1) Replaced the air admittance valves underneath both sinks.
2) Got on top of the unit to ensure the vents weren’t clogged, even ran water down them.
3) Cleaned gray tank, put tons of detergent, fragrances, and cleaning solutions in the gray tank to clean it.
4) Checked the anorod on the water heater
5) Keep the gray tank closed until ready to empty
6) Called the manufacture, they sent out a tech and were unable to find the problem. Have also called multiple service techs and no one seems to have heard of the issue.

Does anyone else have any other ideas? We are seriously bummed about it, my wife and kids hate it. We love the unit except for this issue. Any help is appreciated!

I have a 2022 Forest River Travel Trailer, Heritage Glen

[Bobbo]

You can always put your own P trap in the stinky slinky if leaving the gray valve open.

[ktmrfs]

dougrainer wrote:

ktmrfs wrote:

wa8yxm wrote:
Question: Many advise that when you are on a full hook up site to close your black tank (And they explain the reason I won't here) but leave the gray open till you are getting ready to leave.

NO. Close both valves and dump when you have to.

Why?
Ever see the ads for the RV Black Tank treatments that basically are a waste of money.. A Stinky RV that everyone is avoiding?

Well the Stink is not coming from the holding tanks ..it's coming from the park's sewer system up the 3" hose and into the GRAY tank via the open valve.> Close the valve to block the stink..

EXACTLY ON KEEPING VALVES CLOSED!!!! sewer lines doesn't have a P trap. I remember being at a park several years ago where one camper was complaining to the park about sewer smell at their sight. Cause.... dump valves open.

And a grey tank that is not occasionally cleaned can smell as bad or worse than a black tank. Occasionally before I dump I'll add some laundry detergent to the grey tanks, let it slosh around overnight then drain.

YES and NO. The stink will migrate back thru the BLACK tank via the toilet down tube to the black tank. IF, as the op found out, your GRAY tank system is not installed correctly, then ANY odor(valve open or not) will migrate back into the RV. BUT in a correctly installed GRAY system, the P traps STOP the backfeed of odor. Which is the purpose of P traps. THE MAIN REASON TO NEVER LEAVE VALVES OPEN IS BOTH THE DREADED POOP PYRAMID AND THE GRAY TANK SLIMY DEBRIS FROM GETTING IN THE VALVE CREVISES AND NOT ALLOWING A FULL CLOSURE AND THEN LEAKS. DOug

If the main dump valve(s) are open there is then NO P trap to keep sewer odor from going into the empty tanks, up the vent tubes and out the top of the trailer and then having an odor problem around the trailer like an open sewer pipe. Yes, the P trap in the sink etc. keeps the odor from coming directly through the sink etc. drain into the trailer.

[dougrainer]

ktmrfs wrote:

wa8yxm wrote:
Question: Many advise that when you are on a full hook up site to close your black tank (And they explain the reason I won't here) but leave the gray open till you are getting ready to leave.

NO. Close both valves and dump when you have to.

Why?
Ever see the ads for the RV Black Tank treatments that basically are a waste of money.. A Stinky RV that everyone is avoiding?

Well the Stink is not coming from the holding tanks ..it's coming from the park's sewer system up the 3" hose and into the GRAY tank via the open valve.> Close the valve to block the stink..

EXACTLY ON KEEPING VALVES CLOSED!!!! sewer lines doesn't have a P trap. I remember being at a park several years ago where one camper was complaining to the park about sewer smell at their sight. Cause.... dump valves open.

And a grey tank that is not occasionally cleaned can smell as bad or worse than a black tank. Occasionally before I dump I'll add some laundry detergent to the grey tanks, let it slosh around overnight then drain.

YES and NO. The stink will migrate back thru the BLACK tank via the toilet down tube to the black tank. IF, as the op found out, your GRAY tank system is not installed correctly, then ANY odor(valve open or not) will migrate back into the RV. BUT in a correctly installed GRAY system, the P traps STOP the backfeed of odor. Which is the purpose of P traps. THE MAIN REASON TO NEVER LEAVE VALVES OPEN IS BOTH THE DREADED POOP PYRAMID AND THE GRAY TANK SLIMY DEBRIS FROM GETTING IN THE VALVE CREVISES AND NOT ALLOWING A FULL CLOSURE AND THEN LEAKS. DOug

[Rick_Jay]

Glad to hear it! Thanks for posting your solution!!!!

~Rick

[Itinerant1]

Excellent that you found the culprit. 😉

[ktmrfs]

wa8yxm wrote:
Question: Many advise that when you are on a full hook up site to close your black tank (And they explain the reason I won't here) but leave the gray open till you are getting ready to leave.

NO. Close both valves and dump when you have to.

Why?
Ever see the ads for the RV Black Tank treatments that basically are a waste of money.. A Stinky RV that everyone is avoiding?

Well the Stink is not coming from the holding tanks ..it's coming from the park's sewer system up the 3" hose and into the GRAY tank via the open valve.> Close the valve to block the stink..

EXACTLY ON KEEPING VALVES CLOSED!!!! sewer lines doesn't have a P trap. I remember being at a park several years ago where one camper was complaining to the park about sewer smell at their sight. Cause.... dump valves open.

And a grey tank that is not occasionally cleaned can smell as bad or worse than a black tank. Occasionally before I dump I'll add some laundry detergent to the grey tanks, let it slosh around overnight then drain.

[Wulrich]

FIXED IT! There were one or two comments about the vent pipe not protruding high enough… after taking the vent cap off for the 5th time in the last several months, I noticed that it was under the roof line and that the hole that was cut out for the pipe was not done very well leaving large gaps of space between the roof and the pipe. I ripped the base of the vent cap out, and replaced the entire setup with a Cyclone https://www.homedepot.com/p/Camco-Cyclone-Plumbing-Vent-Black-40597/309587984?source=shoppingads&locale=en-US&&mtc=SHOPPING-BF-CDP-GGL-D25T-MULTI-NA-Multi-NA-SMART-NA-NA-NA-NA-NBR-NA-NA-NA-PortablePower_SmartShopping_HighOrganic&cm_mmc=SHOPPING-BF-CDP-GGL-D25T-MULTI-NA-Multi-NA-SMART-NA-NA-NA-NA-NBR-NA-NA-NA-PortablePower_SmartShopping_HighOrganic-71700000081625943-58700006942154417-92700062499001868&gbraid=0AAAAADq61UcTn6pCWXnwm7_gD2xgmJLE9&gbraid=0AAAAADq61UcTn6pCWXnwm7_gD2xgmJLE9&gclid=EAIaIQobChMIouHW_piA-QIVVMLCBB29kAGfEAQYAyABEgIO1fD_BwE&gclsrc=aw.ds#overlay) and it seems to be working just fine now, no smell!

Thanks everyone for the suggestions! My wife can finally be happy again!

[wa8yxm]

Question: Many advise that when you are on a full hook up site to close your black tank (And they explain the reason I won't here) but leave the gray open till you are getting ready to leave.

NO. Close both valves and dump when you have to.

Why?
Ever see the ads for the RV Black Tank treatments that basically are a waste of money.. A Stinky RV that everyone is avoiding?

Well the Stink is not coming from the holding tanks ..it's coming from the park's sewer system up the 3" hose and into the GRAY tank via the open valve.> Close the valve to block the stink..

[Rick_Jay]

You've received lots of good advice so far. I'm looking forward to seeing what you're able to find.

It looks like this is a new trailer, being a 2022. That is, no one else ever used it before you, and you said this problem began about a month after you took ownership.

It's fairly common for there to be "assembly errors" in the construction of all RV's, and I think perhaps yours might have an issue with the vent pipe leading to the roof. This might have been a problem since it was new, but it took about a month of use before the crud/bacteria/odors built to the point where they were noticeable.

Are your air conditioners ducted? If so, I'm wondering if there isn't a crack or improper seal on the vent pipe which is allowing the sewer gases into the A/C duct channels. Airflow through the ducts will create a low-pressure venturi effect which might draw in an odors "floating around" in that space. Kind of a long shot, but might be possible.

The vent pipe runs between walls. If you open a cabinet door or drawer which is very close to the run of the vent pipe, you might be able to detect a hint of an odor there, if there is a leak in the vent pipe. Closing all windows & doors and turning on your roof vent (exhaust) might help draw in such odors.

For what it's worth, we would on occasion have a gray-tank/sewer odor issue, usually if we were running our vent fan with windows open. We installed that "vane-type" vent cap linked to earlier in this topic and it cured that problem. It seems to make very efficient use of any breeze to create a lower pressure area at the top of the pipe and draw the odors out and away. So, I'd recommend one even if you solve this problem another way.

Good Luck, I'm looking forward to seeing what you find out.

~Rick

[red31]

What is the source of the water from the faucet?

Cabin with well water has rotten egg smelling water, anaerobic bacteria grow in the pressure tank.

[dougrainer]

1. If you flush the GRAY tank and then put sweet smelling stuff in it. You should get sweet smelling odors. ALWAYS. I use Pine sol at our shop
2. You don't even mention the Black tank. The usual suspect in your case IS the Gray tank, but since you have completely flushed the Gray and use sweet smellers, then I would suspect the black tank
3. Is your RV Washer/Dryer prepped? If so, there is usually NO water in the drain tube P trap which stops gray odors. Even if you have a W/D, if rarely used the water drains or evaporates from that P trap
4. You are positive your Battery is not boiled dry?
5. Last, is not an easy thing to do. Your black tank toilet down pipe may not be attached to the top of the black tank and those odors WILL migrate up. Your GRAY tank may have the same problem, either one of the down pipes or even the vent pipe may not be attached securely into the tank. Also the Black vent pipe may also not be attached.
6. The roof vent covers for the tank vent pipes, the pipes may not protrude up into those caps. check and see if the ABS comes up all the way. Another EXTREME cause is the 1.5 ABS vent pipe is indeed ALL THE WAY up and the cap on the top on the vent pushing against the pipe effectively not allowing the tank to vent.
7. RVIA code dictates that correctly installed Tank systems must hold water when on the gray water you overfill until water comes up and the lowest point which is usually the shower or tub drain Black water must come up the toilet down pipe just below the ball valve and hold for 10 to 20 minutes. Doing this test will tell you if the connections on top the tanks are correctly sealed. IF you decide to do this test FLUSH/FLUSH/FLUSH the tanks.
8. USE Pinesol for smell tests.
9. Hopefully you do not have a dead critter someplace. Doug

[pismopete]

Had the same problem with my two grey tanks. Bought a Flush King and back washed both tanks. Problem gone. Now I back flush every time I dump.

[Itinerant1]

Lantley wrote:

JimK-NY wrote:
Do I understand there are no odors unless the A/C is running? If that is the case, I don't see any connection with the grey water. I would check the A/C. Maybe a dead critter in the unit. As mentioned the A/C does not pull any outside air so the offending item would be inside in the A/C or ductwork if there is any.

The AC does not pull outside air but it does circulate interior air if the break or smell is present in the roof line or attic area it will drift into the AC duct system which is not 100% air tight.
Once the smell enters the AC duct the AC system blows the foul air into the interior of the RV where it becomes a noticable bad smell.

Why I mentioned to check vent pipes at roof line if everything else isn't curing the issue, can't hurt to check.

[Lantley]

JimK-NY wrote:
Do I understand there are no odors unless the A/C is running? If that is the case, I don't see any connection with the grey water. I would check the A/C. Maybe a dead critter in the unit. As mentioned the A/C does not pull any outside air so the offending item would be inside in the A/C or ductwork if there is any.

The AC does not pull outside air but it does circulate interior air if the break or smell is present in the roof line or attic area it will drift into the AC duct system which is not 100% air tight.
Once the smell enters the AC duct the AC system blows the foul air into the interior of the RV where it becomes a noticable bad smell.