Quite frustrated. There is an intermittent sewage smell in one bathroom and in at least one bedroom (to a lesser degree). The bedroom is near the bathroom, on the same side of the house, but two closed doors away.

I had my mother pour 2 oz of peppermint oil down the toilet in that bathroom, and then flush, while I was in the basement next to the bathroom drainage pipes. (Bathroom windows closed, door closed). I smelled the peppermint in the basement, though not particularly strongly. I saw no pipe leaks.

When I went back in the house, I smelled peppermint from the range hood in the kitchen, across the house from the offending bathroom and bedroom. It was actually more strong than right next to the bathroom pipes in the basement. I also smelled it from the central AC vent in the house, though not as strongly as from the hood. I smell it faintly in the mentioned bedroom. I did not smell the peppermint in the living room, between the bathroom and the kitchen.

The sewage smell seems to get worse later in the day, after a hot day. It's a one-story house.

I had a contractor who was here for a different job look for a leak in the pipes in the basement, but he didn't see any. Granted, he did not look long. He has no clue what could cause it.

Pulling my hair out. Does anyone have any ideas? Much, much obliged.



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Sounds like you may have a piece of cast iron pipe running through a return air bay
Pipe may be cracked on top where you can’t see it if in fact it is cast iron at all
Could possibly be an old un capped drain also

Time to call a plumber to investigate and maybe do a video inspection

smoke test necessary

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

the peppermint oil must be poured down a vent pipe on the roof.
the person who does the pouring must not come back into the house.
you had the right idea but didn't do it 100% cottrctly.
BTW, mix the oil with some hot water to get maximum effect.

the peppermint test is used while the walls are open

one can merely smell the peppermint, which 'helps' determine where a leak is, but if the leak is in a wall ?



one can SEE from where the smoke emanates, narrowing the issue down to a SPECIFIC wall (hopefully)



methodology will vary but the general idea is to seal off the vents (leaving one open until the system is full of smoke) , plug the house trap or insert a test 'balloon' in a discharge cleanout, and attach a smoke machine to a fixture drain to 'inject' smoke into the piping ~ hopefully the smoke will become visible where a leak exists


there also exist 'smoke detector' tools to aid in pinpointing


you need a specialist 'leak detection' outfit with smoke experience

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

good point packy, flushing the peppermint into a toilet drain already contaminate the living space with it so smelling it is going to be invalid.

if it were me, I will first pour water down each drain (shower, tub, lav, kitchen, washing machine, floor drain) to make sure the traps are filled.

then I will turn off the AC to stop any odor to be distributed through ducts.

then close all windows and doors.

then do the peppermint by a different person up on the roof down the vents.

then the inside person go room by room to detect any odor to pinpoint things. Further steps once isolated may involve having to tape off sink overflow holes, drain openings, bottom of toilet for a possible wax ring seal break etc...



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bernabeu, I think the scenerio about a leak behind walls that may fail the peppermint test is possible, but in this case, the author of this thread can smell an odor but can't trace it to an origin. Assuming this is a leak, that leak is already present and it's odor has made itself known, so a peppermint test should be able to replicate the path of the odor from the leaking point to the home's nose, no?

If no peppermint is detected, then there would be other scenerios, for example, the odor only comes around when positive pressure is experienced by an AAV when a nearby fixture is draining, or a dead animal rotting in a cabinet etc?



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smoke is VISIBLE

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Thank you to everyone for all this awesome information. I have a plumber coming on Thursday. Will a normal plumber be fine or should I contact a specialist, with this particular smoke expertise discussed?

A professional can identify and resolve the issue correctly. A normal plumber may or may not be helpful as advanced techniques requires advanced tools and equipment.

Thank you.

Does anyone have recommendations for someone sure to be able to fix it? I am in Glendale, CA.

Scratch that: does anyone have recommendations for the types of questions to ask when I call someone?



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as per the site 'header'

Quote

..... Please refrain from asking or discussing legal questions, or pricing, or where to purchase products, or any business issues, or for contractor referrals, or any other questions or issues not specifically related to plumbing. .....

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

you may have to contact a plumber first. if they can't figure it out then they will contact someone with proper smoke testing equipment.

I say you might want to repeat the peppermint test but do it properly. The last time the odor was everywhere because once it hits you it's in your nose and you will keep smelling it in every room. Turn the AC off, close all windows and interior doors, have one person pour it down the roof vent, second person go in and sniff each area and see if it hit you.

Have you already ruled out a failed AAV?

I took a look at the roof and there appears to be a vent for each drain (it's an old house). So that means no AAV correct?

Do people have recommendations on what questions to ask when I call, to make sure I get someone capable?



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