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Old 03-08-2023, 12:27 PM   #1
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3230CK Bathroom Sink Stink

We have a 2021 Montana 3230CK with the double bathroom sink. The left sink has a drain and pipe with no p-trap that goes down to about 3" from the floor crosses over to right side and tees into that sink and goes to basement which is where the p-trap is. We are getting that foul gray water smell coming out of the left sink. I'm thinking that the crossover pipe is not sloping down so the gray water is collecting there causing the stink. There's a small amount of room in the holes they cut to raise the pipe a shade, but they have the pipe coming up to the sink tail completely all the way up with no more room to move it.

Does anyone else have this issue and what have you done to fix it? I thinking that I'll start by taking out a chunk of the pipe so that I can create a slope. If that doesn't work, then I'll need to install a p-trap on that sink. Just curious as to why the factory didn't do that on both sinks to to begin with?

Thanks for your comments!
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Old 03-08-2023, 01:08 PM   #2
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Look under the sink for a vent in the drain plumbing. It's designed to pull air in to allow for better flowing without allowing odors into the coach. They tend to go bad and need replacing. They are snug but they do unscrew and are easy to replace. If there is no vent then I'm back to the drawing board.

I bought these to fix the odor in our kitchen area. Problem solved

Also, I suppose that you could eliminate the ptrap in the basement and install ptraps under both sinks if the vent thing doesn't help.

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Old 03-08-2023, 01:55 PM   #3
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My kitchen sink is plumbed exactly like yours and has the vent in the wall that jsb5717 refers to. When I had odor in the kitchen sinks it was the defective air admittance valve. I don't think the slope of your crossover pipe is the issue. Standard pluming only calls for 1" of slope to 4' of pipe. If you think about it gray water is what stands in the standard P-trap and it normally doesn't smell.
I've never known gray lavatory water to smell unless there was build up of hair in the down pipe. (Most always on the women's side of a double sink vanity.) You can remove the stopper in that side and clean the tail piece down to the elbow.
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Old 03-08-2023, 05:17 PM   #4
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We learned about the smell on our first Montana. We tried everything and someone on the forum said that we should check the washer prep. When we drained it, we almost gagged. So, if you haven’t found it, check the washer hot/cold water and drain it.
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Old 03-14-2023, 09:05 AM   #5
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We had this issue in both of the bathroom sinks, although it only smelled when you ran water down the sink drain. I dosed both sinks with lemon gray water tank treatment and so far it has not reoccurred.
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Old 03-15-2023, 03:37 PM   #6
Jim in Halifax
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Originally Posted by Todd & Mary View Post
We had this issue in both of the bathroom sinks, although it only smelled when you ran water down the sink drain. I dosed both sinks with lemon gray water tank treatment and so far it has not reoccurred.
We had the same problem with our '21/'22 unit...It had one of those "newly designed in line/one way WHITE unit in the sink and shower lines.......Added a proper "P' trap on each discharge line in the basement area behind removable wall and no longer have the smell!!!! When I cut the pipe I put an "end" cap temporally on the open end....Poured javex down the sink to fill it to max??? and let it sit for an hour or so.... then VERY CAREFULLY removed the cap and drained into a bucket...Wanted to sanitize inside of pipe of any residue...IT worked...a lot of work!!!!!
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Old 03-18-2023, 03:08 PM   #7
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Stinky Sink Fixed

Thank you to everyone that replied to this. I double-checked and there definitely was not a vent, check valve or anything inline going from the sink tail to the other sink and then to in to the basement. Because the drain pipe went all the way up the sink drain pipe with no room to raise it up, I decided it was worth a try to take out a 4" chunk, and put in a rubber coupler. This raised the crossover pipe a good 3/4" and that did the trick. Haven't had a hint of smell since. So my theory that the gray water was sitting in that 4' of crossover pipe was probably correct.

Thanks again for your responses!
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Old 03-19-2023, 05:47 PM   #8
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Check if the vent pipe is blocked
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Old 04-15-2023, 08:23 AM   #9
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Is your water lines in the bathroom sink also T and go to the clothes washer? I never used the washer lines and they would stink if the camper set unused for a week. You need to put in a shut off to the washer lines and should clear the smell.
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