Trying to track down an odor that has once again shown up, now that weather is getting warmer. I believe it to be a sewer odor, but no water leaks in the sewer pipes. House was built in 1910...with basement, so plumbing is easy to see.

The bathtub, vanity, toilet, and kitchen sink all go into the old cast iron main vent stack, and none of them were vented. I put an AAV on both the kitchen and vanity.

This odor only happens when it gets warm out...70-75 or warmer. Odor seems to come through strong into my closet, which is the backside of where the tub hooks in, but there's definitely water in the trap. Also I can smell it in the basement, and of course the HVAC sucks it in from the basement spreading it around to the entire house.

Just looking for ideas. Maybe a crack in the sewer vent pipe? Just frustrated at this point. I hired a plumber to at least check it out last Summer. His comment, "Well I don't have a real good nose to smell the odor." Ugh. Thanks for any recommendations!

  • Warm weather smell...Again ! All winter long i look forward to the smell of warm weather. Sometimes it gets really warm here, upwards of 68 degree's, and i will sit out on the deck a play Rimsky-Korsakoff's Flight of the bumble bee on my Selmer Alto Mark VI. Perhaps it is a decomposing animal or otherwise not related to the plumbing?
    – Alaska Man
    Commented May 8, 2019 at 16:42
  • Check this question for some ideas. My guess would be decomposing animal based on the fact that it only stinks when it's warm out.
    – Steve-o169
    Commented May 8, 2019 at 17:38
  • On older cast it can have leaks and cracks, in the winter there is not as much of a smell because of the cold but when it warms up the stinky bacteria is active, many years ago I helped a friend replace his early 1900's home lines under the home, it was really bad it had holes in the pipes and black water was in every low point. He had the same issue it only smelled bad in the spring summer months but in the cool fall and winter months no bad smell. I know this as we used to play cards at his house every week.
    – Ed Beal
    Commented May 8, 2019 at 23:28

1 Answer 1


If it's a sewer smell and you are sure that all of the traps have water in them, then it's likely a cracked / broken vent pipe, or a bad DIY addition where they didn't take the vent pipe all the way out through the roof (that happens more than it should because people don't want to end up with a leak in the roof). Call a better plumber. Look for one that does camera inspections, they can snake a long flexible video camera into your vent pipes and look for cracks, dead animals etc. There are also detectors that can "sniff" out odor, it's primarily methane gas and a chemical that is the result of fermentation of the sewage called Hydrogen Sulfide (H2S). Good plumbers have those detectors.

  • Could be a cracked vent pipe, pipe definitely goes out the roof, as I've been up there. Trying to track it down. Fortunately, have some friends at a local HVAC/plumbing company who is trying to narrow down options before making a service call.
    – saxsellers
    Commented May 9, 2019 at 1:21

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