Sewer Smell-Cant Find Cause

[mcikes]

Having a sporadic sewer smell in basement. I can pinpoint the area, its a kitchen drain pipe. Plumber cant verify the cause and said he cant camera the drain beasue its a smaller copper pipe. We think its a cracked or damaged pipe under the concrete as the smell seems to be coming from the inside franch drain that is just behind the pipe. But without verifying I dont want to spend a couple grand digging up my foundation just to find out the pipe isnt damaged. The smell doesnt really show up during the day but is pretty bad at night after 10PM. We sometimes smell it randomly during the day. During the frigid cold days a week or so ago the smell was all day and at times unbearable but seems to diminish when it gets warmer. The pictures show the pipe and area where the smell is emanating from.

 

[MicEd69]

You could try to use peppermint oil to see if that can help verify that the leak is from the pipe. You'll need to have one person do the peppermint oil and another person do the smelling in the basement.

Google peppermint oil testing of sewer pipes. You don't have to go to the roof and use the vent stack for this, just use the kitchen sink drain.

 

[Integrity Repipe]

You could be dealing with a dry trap or faulty air admittance valve. It traps hold water to block sewer gases, but if one dries out or has a small leak, odors can escape. The drain nearby adds another layer of complexity, if there’s groundwater or an open connection to your sewer system, gases might be seeping through. Try running water in nearby drains before bed to see if it temporarily reduces the odor. If that helps, it may confirm a trap issue. If a repair is needed, PEX piping is a great alternative for its flexibility, resistance to freezing, and ability to navigate tight spaces without as many joints that could develop leaks.

 

[Geofd]

Is that area always wet???? Is that a new patch, you could dye the drain and see if you get color coming up thru the slab

 

[breplum]

there is smoke testing. Can be hard to find someone who has the equipment.