Please help — I have an ongoing sewer smell/fly problem in my apartment

[Twowaxhack]

After about 30 minutes if you don’t smell anything you could turn on the hvac.

You don’t want the ac to suck in the smell then distribute it through the condo and saturate the unit with peppermint. Then you couldn’t tell where it’s coming from.

 

[iHateFlies365]

After about 30 minutes if you don’t smell anything you could turn on the hvac.

You don’t want the ac to suck in the smell then distribute it through the condo and saturate the unit with peppermint. Then you couldn’t tell where it’s coming from.

Gotcha, I'll go with that then! Will update when this gets done. Thank you again

 

[iHateFlies365]

UPDATE: so I had the maintenance guy dump 2oz of peppermint extract with about a gallon of water after. I waited 15 minutes without any AC or fans and didn't smell anything noticeable. I turned them on after that 15 minutes and still didn't smell any scent of peppermint. The vent pipe is right above my laundry room and I definitely didn't smell anything in there, on top of the fact that the ducts and vent pipe are not close together (plus the HVAC is supposedly hermetically sealed). I'm pretty certain it's not a sewer gas leak (which is good news), but that still doesn't solve the smell.

My next question is why would the smell come and go? Sometimes it's strong and sometimes it's barely there (or even not at all). It doesn't seem to be tied to any toilet flushing or specific time during the day, just kind of random. Does this even sound like a plumbing issue still, or could it maybe be something else? I'm still perplexed by the flies and the fact that it only affects me and not any of my neighbors below.

 

[Jeff Handy]

Do you live in the Amityville house, that would explain the flies and stink?

 

[Twowaxhack]

Could a neighbor be leaving garbage in their kitchen to rot while they’re out of town ?

 

[Duckbutter]

My next question is why would the smell come and go? Sometimes it's strong and sometimes it's barely there (or even not at all). It doesn't seem to be tied to any toilet flushing or specific time during the day, just kind of random. Does this even sound like a plumbing issue still, or could it maybe be something else? I'm still perplexed by the flies and the fact that it only affects me and not any of my neighbors below.

Going back to my original suspicion, varying levels of humidity/moisture can reduce/induce decay in a small dead animal.

Another possibility, if a trap weir is slowly siphoning due to bad venting, it may have been full during the peppermint test.

 

[Twowaxhack]

I usually pour 8-16 Oz of pure peppermint oil. Depends on how many stacks there are.

Then a quart of warm water down each vent.

 

[PerplexedPlumber]

Could you describe the odor a little better: Is the smell like sewage? Rotten egg? Roadkill? Does the smell change with time, other than the intensity? Is it entirely random, or does it occur within a day or so of a rain? In cold weather and in summer? Is the odor inside your apartment and not outside? In addition to plumbing and possibly rodents or birds, a roof leak could be an underlying cause.

 

[iHateFlies365]

Could you describe the odor a little better: Is the smell like sewage? Rotten egg? Roadkill? Does the smell change with time, other than the intensity? Is it entirely random, or does it occur within a day or so of a rain? In cold weather and in summer? Is the odor inside your apartment and not outside? In addition to plumbing and possibly rodents or birds, a roof leak could be an underlying cause.

Explaining to the best of my ability, it's like sulfur. So I guess rotten egg smell. The smell doesn't change with time as you're asking, really just the intensity. I live in Austin Texas so it's been dry here for about a month now and the smell has come and gone pretty much just as randomly as during the rain, however during peak heavy rains it definitely smelled stronger. And finally, the smell is only inside my apartment. The hallway doesn't smell like it, nor does the staircase down to the first floor (my unit is right next to the stairwell).

I really don't think this is a dead animal problem unless they are just chaining one after another dying nearby for the past three months. By this point the animal would have totally dried up unless it was a grizzly bear that died in the attic or something lol.

I also want to note I got a methane detector off Amazon just to be sure after the peppermint test, and nothing came up. Everywhere in the apartment is the same as elsewhere, so I don't think it's sewer gas at this point. I know this is a plumbing forum, so it seems my time asking for advice here is finished since I've exhausted pretty much everything I can think of. Unless there's something else to check, please let me know. My sanity is dwindled down to practically none at this point.

 

[PerplexedPlumber]

I'm still wondering about a roof leak, especially with the flies. In a cabin with a metal roof, we had a problem with flies getting inside. In this case, the roof had not been properly installed. After having the roof re-installed, the fly problem was back to normal (opening a door lets flies in). Poorly sealed windows or other cracks can also let flies in, in which case the two issues of odor and flies may not be related.

It was wise to try a methane detector, but unless it is a good quality product, it may not be reliable. Either your building maintenance manager or the supplier of your natural gas (city utility company?) will have a qualified, reliable device. It would be good to have your apartment checked for a methane leak at a time when the odor is strong. Pungent sulfur odorants are added to natural gas (and propane) for safety to reveal leaks. Those odorants are a little different from the hydrogen sulfide odor, but if you aren't familiar with the different odors, it may be hard to recognize and describe. Methane has no odor and could come from either a sewer gas leak or a natural gas leak.

Because you are in an apartment, I wonder whether the peppermint oil test may not have worked as expected. Perhaps one of your neighbors enjoyed a nice unexpected mint aroma on that day. Because this aroma is strong, pervasive and lingering, it would be difficult if not impossible to come up with a way to insert oil on the back side of a trap without introducing it to the inside of your apartment.

The city water & wastewater department may be able to measure if hydrogen sulfide is present. That may require a request from the public health department, and the person sent to measure should be able to come out at a flexible time when the odor is strong. If there is no natural gas leak as determined by the gas/utility company device, then the source of the odor may be sewer gas.

By this point, I assume you have eliminated all common issues, such as the odor inside a front-loading washer when the drain port isn't regularly cleaned, or a garbage disposal, or a nearby livestock feeding operation. At a laundromat in our area, there is a smell like this coming from two sources: a very large washer that isn't used often and the restrooom trash can. (We drive a long way to wash comforters.) If the apartment below you or beside you doesn't have the same problem, and you can rule out a natural gas leak, a sewer gas leak seems likely, and these can be difficult to find and repair.

As strongly as you are describing it to be, if what you are smelling is confirmed to be hydrogen sulfide, I would look for another apartment sooner rather than later.

 

[iHateFlies365]

So I spoke with management and the leasing office and they're moving me to a different unit in a completely different building. I'm swapping out in a month so we'll see how that goes, but unless the office looks into it deeper and tells me what the problem was, I don't think I'll ever really know.

It's a bummer since my rent is actually going up a little bit, but in the grand scheme of things my sanity is worth it. I do hope they actually fix whatever it is going on in there, or else good luck to the next tenant

 

[iHateFlies365]

As for the reply from @PerplexedPlumber -- I super appreciate that big write up, and if anything comes up over the next month then I'll see if any of those tips help. Is it possible to be a hydrogen sulfide smell without feeling physically nauseous? Like if it's diluted enough?