Sewer odor from gray tank

[Kjohn7215]

I have been searching the forums for sewer odors and most threads refer to evaporated P traps. My issue is not caused by lack of usage. I get these odors occasional under the kitchen sink, shower drain and currently in my washing machine closet. We are new to living in our rv so please be patient with my lack of knowledge. Yesterday I did laundry and part way through the first load, the odor was slightly noticeable. By the end of the third load of clothes it was unbearable. That was 12 hours ago and I get up this morning to find it is still present. Since all my plumbing is used on a regular basis, could it still be a P trap issue or something else?

We have a 2014 Tradition DVR

[dizcom]

Smells like these can be hard to track down. It sounds like you might have a vent that isn't doing what it's supposed to. When you were doing laundry, was the smell coming from the washing machine or under the sink? Start with where the small is and check out everything there. It's a fairly straightforward system with very few parts. The fix will eventually be quite simple. What makes it hard is that smells can show up in places that are not their sources. There are some other things to try, but start with the physical parts to see if they are all doing what they're supposed to and nothing is leaking. Good luck.

[Lt Dan]

First off, Welcome to IRV2!

Look for what's called an AAV (Air Admittance Valve) high up in the plumbing line. It will look similar to below and it's there to allow air into the drain line. The flapper valve inside is notorious for failing and allowing sewer fumes back into the house.

[Old-Biscuit]

Air Admittance Valves (AAV) on drain lines AFTER the 'P' traps
They open when draining to prevent 'P' traps from getting sucked dry
But they are cheap junk RV MFGs buy by the 10,000's and fail

Black device hand screwed onto a stub pipe
Any Hardware Store $9------better quality ones available for $$

[TXiceman]

Replace the AAV with a better-quality device. As for the washer drain, if it is not in use, simply tape it closed or cap it.

The gray tank can smell as bad or worse than the black tank.

Ken

[Marine359]

Great advice above.
But, An ounce or prevention is worth a pound of cure.
Most gray tank odors originate from decomposing organic matter like food particles entering the gray tank from one of the sinks. Hair into the tank, from shaving face or legs can also start to decompose. Beverages with sugar or carbs are bad news. In other words, (pretty much) if it ain’t nearly clean H2O, don’t allow it to get into the gray tank. Flush all that other stuff down the toilet. Once a year, it’s also a good idea to introduce a small amount of diluted bleach into the gray tank. Being careful not to allow it to sit in traps, so chase with lots of water, at least 10 gal. Drive around to slosh the tank, and dump. We’ve been doing this for 40 years, and have never had gray tank odors. If you have a washing machine, you may need to disinfect and flush the tank more often.

[Kjohn7215]

Thank you. The smell was coming out of the drain hose so at least we do have a starting place.

[Kjohn7215]

Thank you. I’m assuming we need to take the panel off the wall to look for one by the washing machine drain.