I have noticed an odor coming from the cabinets where the kitchen sink is. I have looked for any leaks where the sink is, but have not found any. Could the odor be coming from the sewage? How can I tell? If so, then what can I do to get rid of it? Any help would be a appreciated. Thanks.

If you have a dishwasher next to it, check it for leaks. Make sure there is a trap in both the sink drain and dishwasher drain, the double "U" shaped thing where it goes down, turns, and turns and goes back down. The bottom turn should stay full of water, preventing sewer gas from coming up the drain.

If you can, check the crawl space below the sink, and see if there is any sign of a leak. Something could be leaking between the sink cabinet bottom and the floor. A mouse or rat could have gotten in there and died.

Could be a tough problem. Maybe somebody else will have another idea.

Hey Rusty, Labman gave you some great places to start looking. However all dishwashers discharge into one of two places. If you have a disposal it discharges into the opening provided for it and if no disposal then we install a "dishwasher branch" that replaces the tail piece from the kitchen sink drain. So you will always be trapped. Try this. Pour 1/2 gallon of bleach into your disposal,( if you have one, if not then down the sink drain) Let it set overnight next morning flush it out with a pan of boiling water. If you have a disposal, you can then cut a lemon into quarters and run it through the disposal. For a odor that originates from UNDER the cabinet I like Labmans sugestion. If you can, check the crawl space below the sink, and see if there is any sign of a leak. Something could be leaking between the sink cabinet bottom and the floor. A mouse or rat could have gotten in there and died. Good luck, Tom

I do not have a dish washer or a disposal. Have cleaned out the cabinets to see if something like mouse might have been there,but no signs of that. I think it is coming from sink pipes. I think it is sewer gases. Any idea how to fix this?

If the drain has the proper trap, and no leaks in the pipe, the sewer gas shouldn't be able to come out. It is possible some foul smelling material is sticking to the pipe above the trap. Try filling the sink with hot, soapy water and suddenly letting it out. Pouring boiling water down the drain might help. Some of you foaming drain cleaner might solve the problem too.

I have the same problem in my house. There is a very strong sewage smell coming from UNDER the sink. Opening the cabinet doors makes this very clear (juck).

Since the smell is coming from under the sink, it indicates to me that the problem has nothing to do with the sink itself.

It seems to me that this means that one of two things is happening:

1) An animal is dead in the wall. I don't think that's it, because it is smelly only under the sink cabinet. An animal could have died in any wall in the house. That doesn't eliminate this option of course, just make it less likely.

2) The smell is coming from a crack or leak in the pipe.

Going with option 2 as the most likely, and checking for leaks under the sink revealed nothing. However, the crack may be in the wall past the point where the pipe is visible.

I was thinking that one way of checking this would be to disconnect the pipes and cap that end of the pipe (just use duct tape) for a day. I don't want to get into tearing up the wall if I'm not sure.

Is there a way that sewage gasses could leak out if water doesn't leak out? There is no water leak under the sink.

Any other suggestions how the smell could originate from UNDER the sink?

You could very well have a leak in the lateral,(horizontal drain pipe) in the wall, and if your house is built on a slab, never see the moisture. It would seep out under the cabinet and just lay there and smell. If that's the case then capping off the pipe wouldn't stop the smell. I had the same problem myself when a copper pipe corroded through. I had to bust a concrete block wall from the outside to replace it with PVC. Just one suggestion. Tom

Hi Speedball1.

Yes, that is my fear, and capping the pipe should clear up whether it's in the wall or not. If the smell goes away, then it is not in the wall, if it persists, then it is in the wall. Here's my reasoning.

If the smell comes from a section of pipe that is in the wall, then after capping the pipe, the smell would still come through, because it is not going through the pipe, it is coming out somewhere in the wall.

If the smell has to do with the part under the sink, then capping the pipe will stop the smell, provided of course I flush everything with hot water first. Capping the pipe will stop the smell from coming into the area under the sink.

The area under your sink is called,(from the drain on through the wall) Basket strainer, tailpiece, trap,("J" bend) and the part the goes into the stubout is called the trap tail. If sewer gas were escaping from any one of those that would mean moisture could also get out. If running your hand from the sink to the wall didn't pick up any moisture then the cause of the smell is somewhere in the wall. While capping off the pipe would prevent fresh moisture from escaping that would still leave the liquid that is smelling up the place intact. It wouldn't just dry up overnight. There's a great difference between the rotting flesh smell of a dead critter, sewer gas and the smell of a leaky drain. You can tell the difference by sniffing the basket strainer and then sniffing under the cabinet. While it's possible you have a dead mouse under the cabinet floor my bet's on a leak in the wall. Do you have a basement where you can check for moisture or are you on a slab? Regards, Tom

I'm on the second floor, and there is no leak evident below. I'll run another thorough check for moisture under the sink (while running lots of water), and if I don't find any, I'll rip out the drywall to see where the pipe is going and if it's leaking in there.

If I do find a leak, should I take out a section of pipe and replace it, or can I use one of the pipe repair kits they sell at the hardware store? I think they basically involve some kind of contraption that wraps around the pipe and is tightened with a mechanical fastener.

Thanks for the help, I appreciate it.

If the pipe's ate up don't try to repair it. It will just leak again. When mine went it ate the bottom right out of a 1 1/2" type L copper pipe. I had to break a outside block wall to get to it. That was two years ago and I replaced the pipe that went from the stubout ell to the stack. This year the stubout went and I had to break into the wall again to replace it. Profit from my mistake. If you find a section of the lateral drain line bad, replace the whole arm and stubout with PVC. Good luck Tom

I am also having issues with smell coming out of my sink.

It is intermittent however and only seems to come out of the side where the garbage disposal is located. I plan on trying the bleach and lemon fix first but I wanted to know if anyone had any other suggestions.

Is there any reason it should be intermittent?

Kevin

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Originally Posted by kevinp

I am also having issues with smell coming out of my sink.

It is intermittent however and only seems to come out of the side where the garbage disposal is located. I plan on trying the bleach and lemon fix first but I wanted to know if anyone had any other suggestions.

Is there any reason it should be intermittent?

Kevin

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Hi Kevin,

Before the bleach and lemon flush the disposal out with a few pans of boiling water. That will loosen the grease and let the bleach do its work.
You ask, "Is there any reason it should be intermittent?"
Does it just stop dead for a second or two or does it hum when it stops?
Good luck, Tom

Hi Tom,

To be clear, the disposal doesn't stop just the smell.
I will flush with the boiling water first.

Since the smell's intermittent I probably won't know if it really worked for a week.

If there are any other suggestions please post.

Thanks.

Kevin

Wondering if an AAV might be the culprit? I have the same problem as some of the others on this thread. My house is just under 4 years old and this past summer we developed a nasty smell from under the kitchen sink. I've checked for leaks everywhere and there are none and I checked the only vent line that exits the roof and found no blockage. Since our sink is part of an island in the kitchen, there was no covenient way to run a vent line so the plumber used an AAV. Does anyone know if it's possible for an AAV to seep sewer gas? The device seems to be functioning properly as there is no sign of slow drainage. The smell seems to be more prevalent when it's humid outside, which only adds to the mystery. Any info would be greatly appreciated.

Hey Stew,

Since the AAV is a air vent you would see no water coming from it. Yes, it's very possible that a spring weakened in the unit allowing sewer gas to escape. I would change it out at the earliest. When it's humid outside the air's heavy and the sewer gas instead of raising to the ceiling stays low where you can smell it. Good luck, Tom

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Originally Posted by speedball1

it's very possible that a spring weakened in the unit allowing sewer gas to escape. I would change it out at the earliest.

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It seems as though there's a wide variety of AAV's on the market at varying price points. I'm assuming the one we currently have is on the cheaper side given the fact that it seems to have failed after only a few years... is there a particular brand that you recommend over others?

Hi Stew,
Yes, Studor Vents are manufactured just North of where I live. The nicest thing I can say about then is that I've never had to go back and change one that's gone bad. You may check them out at;
http://www.studor.com/homeowners.htm Good luck, Tom

I have the same problem and have tried the boiling water, etc without success. I called a plumber who came over but found nothing. I think I was ripped off though because he wasn't even going to check the trap until I suggested it. The smell is still there and it's been about three weeks now. What is an AAV? My sink is on a peninsula if that makes a difference. Thx.

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Originally Posted by apple blossom

What is an AAV? My sink is on a peninsula if that makes a difference. .

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Hey Blossom,
You have a island sink with a AAV. A AAV, (Air Admittance Vent) is a spring loaded mechanical vent that replaces the need for a outside roof vent.
They are installed in island sink installations in place of a loop vent. Look under your cabinet for a thingy at the top of your drain line that looks like this. http://www.studor.com/homeowners.htm
If you smell sewer gas this could mean the spring in the AAV has loosened and isn't doing its job. Let me know what you find. Tom