Sewer odor issues

[Cbrandt79]

Hello fellow Montana owners

We have a 2021 3120rl legacy and I am experiencing sewer odor that I cannot get rid of. I have removed the cap on the roof vents and flushed with water. When I dump I use one of the camco rhino blasters I wash the tank with this 3 or 4 times with a water gauge putting 10 -14 gallons of water in tank then dump. Usually runs very clear/ clean on the last rinse.
I also removed and inspected the air emitter device under the sink in the galley. We have a splendid washer and stack dryer as well. Wife runs it constantly! We were full time for the last 3 years. We have been in Arizona for the last 6 months. We use happy camper and also put at least 4 gallons of water in tank after dumping.
No signs of leaks! Any suggestions are really helpful and appreciated

[RMcNeal]

Is it possible the gray tank is the culprit? Believe it or not, once some mold grows in there it can get quite smelly and smell like it is from the black tank.
I've used the Unique tank cleaner on both black and galley gray tanks before with good results.
https://www.amazon.com/Unique-Cleane...11&sr=8-6&th=1

[DutchmenSport]

Actually, my kitchen sink holding tank smells worse than the black tank. I have the ability to dump my grey tanks on the ground at home, and my black tank always goes to my septic tank. But when dumping the kitchen sink, it smells horrible.... I mean horrible.

I started using an Enzyme eater in all my tanks, add some after every dump. It takes only an ounce. And amazing, my kitchen sink tank doesn't smell near as bad as it use to. It still has a bad smell, but NOTHING like it use to.


In all the years we've had an RV and working with the tanks, by far the kitchen tank smelled the worst. So, yes, it's highly possible the problem is really one of your grey tanks.

Add some enzyme eaters and let it do it's work. Just add an ounce after every dump. See if that makes any difference over time.

You don't want a deodorizer, get something that actually eats the bacteria.

[FloridaFiver]

We are careful not to allow greasy or fatty dishwashing water to enter our galley tank
Wipe off pots pans and dishes into the trash before washing them

Keep fat out of the tank that can go rancid helps allot

We treat our galley tank with this stuff

Add as
Directed and allow tank to come full before emptying
https://www.justscience.com/tanktech...tank-treatment

Hope this helps

[jsb5717]

Originally Posted by Cbrandt79

…
I also removed and inspected the air emitter device under the sink in the galley. …

Did you replace it? Yours is old enough to need it. They are inexpensive and easy to replace. Can’t hurt to just do it and see if it helps.

I bought a 3-pack of them on Amazon a couple years ago when ours was stinking. Problem solved with 2 spares for future needs.

[Foldbak]

Originally Posted by jsb5717

Did you replace it? Yours is old enough to need it. They are inexpensive and easy to replace. Can’t hurt to just do it and see if it helps.

I bought a 3-pack of them on Amazon a couple years ago when ours was stinking. Problem solved with 2 spares for future needs.

Can you please explain how this valve works with the black tank? Or did I misread?

[jsb5717]

Originally Posted by Foldbak

Can you please explain how this valve works with the black tank? Or did I misread?

It’s for the galley gray tank, which, as stated by others, can smell as bad as the black tank. When our air admittance valve was failing we kept getting an awful sewer smell in the living area. When I realized the smell was coming from under the kitchen sink I figured out the valve thing. You can’t tell that they are bad by looking at them. When the smell starts, just replace it.

The purpose of the valve is to allow one-way movement of air to assist draining since there is no drain venting through the roof as there is in the bathroom. A failing valve begins to allow 2-way moving of air. Hence gray tank smells backing up into the living area.

Look under the sink in your island. You’ll find a vertical capped drain pipe. That’s it.

I bought this 3-pack. So far still on the first one
https://www.amazon.com/Oatey-39012-L...s%2C183&sr=8-4

[AZ Traveler]

This is a great tool to help you flush gray tanks.

https://www.amazon.com/Valterra-Degr...s%2C431&sr=8-8

[Cbrandt79]

Thank you all for responding to my stinky question. I will next try replacing the toilet gasket at the floor flange. Still frustrating with the stink!

[Cbrandt79]

Use it all the time

[Cbrandt79]

Originally Posted by Foldbak

Can you please explain how this valve works with the black tank? Or did I misread?

It’s for galley sink.

[Daryles]

Originally Posted by Foldbak

Can you please explain how this valve works with the black tank? Or did I misread?

Here's a diagram of the air admittance valve and how it works.

To troubleshoot (confirm its the source of the stink) put a baggie over it and tape it off sealed shut.
IF the stink goes away, that's it.

There is one under the kitchen and bathroom sinks

[BB_TX]

The purpose of the air admittance valve or a roof vent is to keep the drain pipe from siphoning or suctioning all the water out of the P trap since that water is there to prevent odors from coming up thru the drain.

[Budman229]

It's possibly coming from the UniGard Waterless P Trap under the shower.
We have a 2021 3121RL and had the same issue. Traced it to the shower drain. Got a new trap from Etrailer.com. Very easy to install. Just had to pull back the curved wall behind the wet bay to access. Took 5 minutes to install.
Problem solved.

https://www.etrailer.com/RV-Sewer-Ho...l/LSB24FR.html

Paul

[Ttman]

I mirror DutchmenSport, I use the Zep Drain Defense every other year, and it works amazing. We also dont use any of the commercial tank treatments, we use a mix of pine-sol, Calgon Beads and water based on the recipe and recommendations of the RV tank clean people. The combination of both for us limits any tank smell for us.

[twindman]

Have you tried putting some water in the basin of all the various sinks and toilet and see if you get any smell?

[Bsmike1965]

The roof vent for my galley gray tank separated at a joint in the basement storage area. The pvc was cut too short. Had to extend length and reconnected it. Got rid of our mystery odor. It was a tight area to get to. Had to send my 12 yoa daughter in there and talk her through what to do.

[Maddog]

https://www.bing.com/shop/productpage

Lippert 360 siphon rv roof vent cap

[DABOO77]

Hello and good day
We have never experienced an odor problem as you described but the valve under the sink makes sense. Just as a try / experiment you could try a heavy dose of bleach in the hoding tanks. Fill close to capacity and go for a drive to slosh around / cover all surfaces, let sit overnight then empty and see what happens. I've not personally done this or heard of anyone doing this--just an idea.
good luck

[Cbrandt79]

thanks!!