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Bad odor in trailer after traveling


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We took delivery of our LE2 on September 16th, and are in the Las Cruces NM area at a Harvest Host winery enroute home to Northern California. Twice now while traveling with partially full gray and black water tanks to our next destination, upon arrival we have discovered that the trailer has a terrible odor inside. The shut off valve near the base of the toilet was closed, so gray water has not backed up into the shower pan. There was no problem with the toilet. The source of the odor seem to be coming from the kitchen sink, because when we removed the cutting board, the odor was stronger.

The only thing I can think of is that the water in the P-trap for the kitchen sink somehow got displaced while traveling on bumpy roads, and that would allow odor from the gray tank to get into the cabin, but this seems unlikely. Any ideas how to prevent this problem from happening? Obviously there are times when we have to travel to our next destination without having dumped the tanks.

2021 Legacy Elite 2 Twin Bed | Hull Number 894 (9/16/21 delivery) | Ram 1500 Longhorn 4x4 3.0L EcoDiesel 3.92 axleAZARCAIDMTNVNMORTNTXUTWAsm.jpg

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There just might be a couple of reasons for the odor.  Perhaps the easiest thing to do would be to get a grey tank odor treatment and try that following the directions - something like THIS - available at most RV places, Amazon and many Walmarts.

The next thing is to look at the vent to make sure that it isn't clogged and/or the vacuum breaker under the sink to make sure it is operating.

Good luck.


2023 Ford F150 Lariat 3.5EB FX4 Max Towing, Max Payload, 2016 Oliver Elite II - Hull #117 "Twist"

Near Asheville, NC

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We picked up our trailer in February and everything has been good until our last trip. Twice during our 16 night trip my husband & I noticed this same thing. And after dumping with only clean water & chemicals in the toilet it had the same smell. We also decided it wasn't from the bathroom. It was also after traveling from one place to the next. My husband will be glad to hear he wasn't imagining it. I will direct him to this post to get some ideas.


Charlie & Cindy / Cleburne, TX / 2021 Elite II Hull #743 / 2013 Ford F250 Diesel 4WD Supercab

States we've camped in our Oliver:


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Pull out the lowest drawer under the sink and check to see if water has collected under the drawer. If the faucet leaks the water may run down the pull out sprayer line and collect on the wood panel under the drawer. The pull out sprayer line on mine is routed through the opening at the back of the drawers so the water did not run into the basement where it could leak out the scuppers. The wood started to macerate and caused a nasty stench, laced with ammonia on hot days. Hopefully this is not the source of the bad odor because it was a mess.

Jerry & Kathy

2019 LEII Standard #539 + 2019 Tundra Limited 4X4

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My trailer #218 does that when climbing really steep mountain grades, such as 5000 feet in half an hour, the sudden pressure change burps the grey water odor out the kitchen sink trap. I started using a little Camco TST and that is no longer a problem, it kills the nasty odor and adds a bit of lemon scent.There may be something wrong under the sink, in looking at my plumbing diagrams, there is another vent for the grey tank other than the one in the bathroom, mine may be dysfunctional since the sink burps and the grey tank is really slow to drain if the travel valve is closed..... Does anyone know if it is a TWO way valve, or just for either negative or positive pressure?





You don't need to add the full recommended dose of 4 ounces of TST unless you know the tank will get completely full, I usually dribble in a couple of ounces max. One reason I like it is that every Walmart has it in the RV section for around $7. I save the bottles for other uses, like carrying bleach (water treatment), vinegar (composting toilet)  or mineral oil (drain valve lubricant). The bottles store neatly in the pantry without taking up as much space as the big round bottles. Be sure to relabel them! The original labels come off easily.


Spokane WA

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SOLD 07/23 "Mouse":  2017 Legacy Elite II Two Beds, Hull Number 218, See my HOW TO threads: 

Tow Vehicle: 2013 Land Cruiser 200, 32” LT tires, airbags, Safari snorkel, Maggiolina Grand Tour 360 Carbon RTT.

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1 hour ago, John E Davies said:

Does anyone know if it is a TWO way valve, or just for either negative or positive pressure?

It's supposed to be one way, as an inlet.  But like Bill suggested, the seal can go bad or be bad for the factory.  It's easy to unscrew and inspect, if a little hard to get to, if you think yours doesn't seal well.

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Corvus, there’s no leak under the sink.

Topgun, after the first odor incident, I added happy camper brand black tank additive to the grey tank to see if that would help. Perhaps that’s not the right product, I will try the one you recommended. I am not sure from John’s diagram where the vacuum breaker is located, and if the gray tank vent goes out through the roof.


2021 Legacy Elite 2 Twin Bed | Hull Number 894 (9/16/21 delivery) | Ram 1500 Longhorn 4x4 3.0L EcoDiesel 3.92 axleAZARCAIDMTNVNMORTNTXUTWAsm.jpg

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