Bathroom sink drain stench

[Noreen]

Hello friends
Have a 2022 NP 377rlbh.
While using the bathroom sink. There is a terrible stench. We’ve tried the vinegar/baking soda cleanse. It works only for a short time. Then the stench returns.
all other drains are fine.
Can any one please explain?
TIA.

[ARoamer]

Could be a few different things.
Here's some previous posts----->


OK, so my grey tank is probably the most sanitized grey tank around now but still have the problem. I started tracing it further and have found it to actually be in the cold water supply line. I am connected to city water but intend to disconnect and sanitize the water lines. I discovered this by opening the low point drain located in the basement. Both hot and cold low point drains there but only the cold had odor.

you may have a faulty air admittance valve under the sink. It admits air to the drain line to help it drain, and has a one way valve that is supposed to keep odors from escaping.

my problem was a defective "anti syphon" valve, located by the p trap, under the bathroom sink. Easy fix once the problem was found.

Have you tried replacing the "cheater valve"/anti syphon valve, near your P-trap. This solved our problem. We had our gray water tank valves "open" while connected to a sewer dump on our "full service" site. The "cheater valve"/anti syphon valve would typically stop odors from coming into our unit, but, ours wasn't working.

[Noreen]

Thank you so much, it’s our second year with the rig. We didn’t even realize we had two gray tanks? He thinks that tank was always open. Therefore, letting the odor in when we ran the water.
We do believe it is the cheater valve.

[RogerR]

Try the smoke test. With water running at max in the sink use the smoke from a cigarette or blown out match and see if the under sink vent is leaking out. If it is then also check that the roof vent pipe is clear. (or maybe check it first. ) Look down with a flashlight and/or drop a string with a small weight down it to see if you have a blockage. In the past I have seen postings where the roof vent pipe was never connected , broken or loose.

[JimD]

Saw this thread and didn't think too much about it until it just happened to me.

I had just finished washing dishes and pulled the plug on the drain. All of a sudden the entire RV smelled like a sewer. Never had that happen before. My wife said she heard the water gurgling through the pipe under the shower. The shower has a plug in it preventing any escape from there. I think the smell mainly came from the bathroom sink and maybe the kitchen sink.

I see that there are air admittance valves in the plumbing that I will replace before the next trip. I was wondering if the tank vent was plugged but when I looked at the roof, there is only 1 vent cap and it is right next to the bathroom fan vent. I always assumed that was for the black tank.

I have noticed my gray tank drains fairly slowly even though I always remove the kitchen sink drain plugs to allow air in.

My question is - should there be a tank vent to the roof for the gray tank or is it possible that Jayco tied the single vent pipe to both black and gray tanks? Inquiring minds want to know.

[Jerry713]

Originally Posted by Noreen

Hello friends
Have a 2022 NP 377rlbh.
While using the bathroom sink. There is a terrible stench. We’ve tried the vinegar/baking soda cleanse. It works only for a short time. Then the stench returns.
all other drains are fine.
Can any one please explain?
TIA.

I would treat and flush that tank as if it was your black tank. Had the same thing happen with mine and after about 5 treatments and flushes using Unique tank treatment the smell went away. I now routinely treat all my tanks with Unique.

[CAG]

How much hair and other gunk is filling the trap under the sink? Those need to be cleaned periodically especially with the amount of hair that goes down the sink and trap in that bend.

Vinegar and baking soda does not dissolve hair and the entire mess grows fungi.


I have to pull my wife's bathroom sink trap every so often as the amount of hair creates some major smell issues. Mine too but not as often.

[Noreen]

Hello friends,
Please help with more suggestions.
We are still dealing with the sewer stench coming from only the bathroom sink. I 100% believe it’s coming from the water.
We changed out the p-trap, air vent under sink and Took apart water lines that are attached to the sink faucet apart and flush lines with bleach.

Previously with pour multiple times vinegar and baking soda, CRL, bleach,
Product for gray tanks.

We just don’t know what else to do.

[RogerR]

My water smelled terrible when I forgot to drain my hot water tank while in storage for 6 weeks. As a result the water had a terrible smell like rotten eggs and I never tried to drink it.

I cured it by simply running city water through the system to flush out the bad smell. Now I try to remember to drain the hot water heater any time I store it no matter how short the time before next use.

Several others have posted similar experiences.

[AZDIESELPIG]

Originally Posted by Noreen

Hello friends,
Please help with more suggestions.
We are still dealing with the sewer stench coming from only the bathroom sink. I 100% believe it’s coming from the water.
We changed out the p-trap, air vent under sink and Took apart water lines that are attached to the sink faucet apart and flush lines with bleach.

Previously with pour multiple times vinegar and baking soda, CRL, bleach,
Product for gray tanks.

We just don’t know what else to do.

Keep your valve closed and see if that helps.