I moved into my first apartment in August. The apartment is a 3rd floor 2 bedroom apartment and it’s great except one persistent issue that has gotten worse over the last few months.

The master bedroom’s bathroom hasn’t been used in weeks because of a strong smell whose origin seems to be very difficult to locate. The best I can describe it is as a urine smell but slightly different maybe like urine and mildew or something like that. It’s kind of a bitter smell, if that makes sense.

The smell is also present around the air conditioner closet and from outside the apartment on the wall that faces the bathroom. I also noticed a black grime on the vinyl panel on that wall. (Hence my mold fears)

I called maintenance but they essentially said: "This room doesn’t really smell any different than any other room in the house."

I’ve cleaned the bathroom and found the smell to go away for a brief couple of hours and then return harsher.

I’m posting here because the only thing I can think to do other than keep calling maintenance (which I plan to do) is to ask others if they’ve had a similar experience. I want my apartment to be complete.

My only guess as to what it is would be mildew or mold, but I cannot find anything in the bathroom itself. Could it be mold in the walls? How do I go about solving this issue?

  • 1
    Mold doesn't smell like urine. How about sewer gas? Is it possible you have a drain without a proper trap, a "dry" trap, or just a leaking pipe or fixture? Also it is possible that the previous tenant had animals (or people for that matter) that urinated on the floor or carpet?
    – jwh20
    Commented Dec 7, 2020 at 15:38
  • @jwh20 I haven’t noticed any leaks. To be honest I have no idea if there is any issue with the drains, but I know that the smell doesn’t seem any stronger near the drains. As for the urine smell: urine is the closest smell I can compare it to. I have cleaned the floors thoroughly and the smell has come back. Commented Dec 7, 2020 at 15:41
  • My thoughts in no particular order. A rodent has died and is decaying behind a wall. Your traps are drying up from dis-use so get some water in your drains. Your downstairs neighbor is an utter slob and their smell is affecting you. The sewer gas vent might be located very close to your bathroom window and the wind will blow the gases into your apartment.
    – MonkeyZeus
    Commented Dec 7, 2020 at 19:14
  • Curiously, does your 2 bedroom apartment have 2 bathrooms? That's quite a luxury :-)
    – MonkeyZeus
    Commented Dec 7, 2020 at 19:15

1 Answer 1


There may be several possible sources of the smell. First let's address the mold issue. Generally mold thrives in moist environments. What is the climate where you are at. You may need to run a fan to air out that bathroom for a bit.

Second, sewer and toilet area issues can contribute odors as well. For example, a shower which isn't used may have a trap which has become dry. Sometimes one will hear water running, having higher frequency splashing noise than water in pipes. That may happen with a trap, usually a kind of S curve which blocks gasses from entering the house, from the sewer. That could be a shower or tub, but it could also be a sink. Run some water down every drain, and see if the odor diminishes.

Third, there can be secondary effects. For example, the bottom of the toilet usually has a wax ring. If someone poured hot water down the toilet, it could soften that ring and cause a leak just large enough for sewer gasses. Also, if the toilet were loose in it's setting, that could also permit the development of a crack in the wax ring.

Like toilets, sink drains can also get small leaks, which will permit gas to flow but may not leak visible water.

For a path forward, I would first dry out the bathroom. I would get rid of any visible mold, whether black or light tan. Consider a bathroom cleaning product with a mildewcide in it. The major brands have products like this and you can always call their consumer help line for recommendations. Run the fan to get the room dry, and to reduce the odor. Opening windows may help.

Then run some water into every trap (drain). And then wait and sniff. See if you can identify where and when the odors appear.

Also, is there an apartment above you? If the wall which is on the outside has outlets, do you smell the odor near the outlets?

Lastly, there could be a defect in the plumbing in the wall, or even leaking from another apartment adjacent or above you.

  • My apartment is the top level apartment and the wall that I’m talking about faces the middle outdoor hallway between apartments. Is the wax ring with the toilet visible from the outside? Also about the drain traps you are talking about, why should running water help with the odor? How long should I run water down the drains? It’s particularly interesting to me because we haven’t been using that bathroom at all so if that could cause it then perhaps it has. Commented Dec 7, 2020 at 16:27
  • I’m in central Alabama so it can get pretty humid. There is no visible mold anywhere as far as I can tell. Is there any way I could seal the drains to determine if they are the problem? Also what’s your take on the smell being outside and around the air conditioner closet as well? (They are in close proximity to the bathroom) Commented Dec 7, 2020 at 16:28
  • The wax ring is concealed under the toilet, and if it were defective the landlord maintenance people would likely replace it. For the drain traps, a quart or so of water is plenty. I suppose it could have a little bleach in it. Like 1/2 cup laundry bleach (sodium hypochlorite style, not the sodium hydroxide splashless kind) per gallon of water. The room will definitely get a bleach order for a couple of hours. Give an update so we know what you found, or to clarify your question.
    – mongo
    Commented Dec 7, 2020 at 16:32
  • 1
    @FreeMan I ran water and bathroom cleaner/disinfectant down the drains for at least 20 minutes. The smell seemed to go away. (Being cautiously optimistic because iI had both fans running and the window open to draw the air out.) I will let it air out for a few hours and then close the door and shutoff the fans to see if the smell comes back. One positive sign though is that the smell wasn’t present outside by the wall like I mentioned before. It makes me think it could be sewer gas. Commented Dec 7, 2020 at 18:25
  • 1
    @pocketonion A p-trap literally holds like 2-3 cups of water; you can see the piping directly under your sink. 20 minutes of running water was total overkill ; 2-5 seconds should have been enough. I recommend doing it once a week or whenever you notice the smell returns; your choice.
    – MonkeyZeus
    Commented Dec 7, 2020 at 19:20

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