I rent an apartment in a highrise, and often smell a faint sewage smell when there are high north-westerly winds with gusts. Following suggestions on a past Stack Exchange posting, I did the simple test for a dry P-trap under the bathtub, i.e., putting my ear to the bathtub drain and listened for the flush of the adjacent toilet. The P-trap doesn't seem to have dried out.

What are some other possible explanations of a faint sewage-like smell in a highrise bathroom, occurring only when there are high winds coming from a particular direction?

  • it could be coming in from outside if you are near the top of the building
    – jsotola
    Jan 1 '19 at 19:11
  • I'm on floor 9 of a 20 story building, so I suspect not. Jan 1 '19 at 23:34
  • Are there any other P-traps that might have dried out? Sinks, floor-drains, laundries, dishwashers... Jun 25 '20 at 13:04
  • No, it's a small apartment with only the kitchen sink, bathroom sink, toilet, and bathtub. Jun 26 '20 at 0:23

Strong wind gusts here in Toronto will cause the water level in my toilet bowl to move up and down, almost as if it were being plunged. I'm on the second floor of a century factory loft. The wild variation in air pressure during strong winds must put pressure on the vent stack. Sometimes the water level in the toilet drops low enough to allow air from the stack to gurgle into the apartment. This is the kind of scenario that could be alowing sewer gases into your apartment, either through the toilet, tub, lavatory sink or kitchen sink.

  • It could be, at least for the drains (not the toilet, I never see any signs there). But I never hear anything that would suggest this. I wish there was a way to be sure. Aug 2 '20 at 23:13

If the high-rise was built before the 1980's then the plumbing stacks/vents may be composed of cast iron and galvanized steel. It's not uncommon for the cast iron to develop a crack where it is located in an area of concealment behind a wall. It's also not uncommon for the galvanized steel piping that connects to the cast iron to develop rust-through at the threaded connections. Either of these conditions can create a breach in the sewer odor confinement system i.e. the vent stack. When combined with variable air currents both inside and outside the building you can easily get a sewer odor in your unit. Have you told the building mgmnt. about the problem?

Do you have a floor drain perhaps located inside your laundry or mechanical closet? The integral drain trap could dry out and allow sewer gas into the home. It's best to pour a half gallon or so of water down the floor drains every couple of months in order to maintain the 'trap seal'.

  • Getting management to do anything is a lost cause unless there is something visibly in-one's-face. It took a year of exhortation before they would do a bit of vacuuming of the exhaust ventilation for the bathroom and kitchen range hood. That was when there was visible condensation on the windows causing mold. Unfortunately, I don't have a floor drain or even a mechanical room. It is a mere 1-bedroom apartment. Fortunately, the wind shifted when I got back, so the smell is gone. When it recurs, I again ruminate over what can possibly be done. Jan 1 '19 at 23:37
  • But thanks for weighing in. The building is 80's era, but in Canada. I posted this question in hopes that the responses would provide enough information to further characterize the problem to the extent that I would feel confident that I could get management to do something. Jan 1 '19 at 23:38

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