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Sewer smell mystery...

kcoppkcopp Posts: 3,412Member
Yes its not relating to heat. New customer calls to find out where a bad sewer gas odor is coming from. It is bad. Seems to be worse the colder it is outside. House is -10 yrs old. I have walked through every inch of the house looking for dried out traps and open pipes. Seems to concentrated in one section of the house and I sort of have it down to a pipe location. Pipe is not leaking, looks fine at the joints.Does not appear to be cracked. It is foam core pvc. Has anyone out there had/ heard of issues w/ sewer gas getting through  foam core pvc into the house.


  • Paul48Paul48 Posts: 4,492Member

    think you're going to have to smoke test it.
  • icesailoricesailor Posts: 7,265Member
    Smelly Foam Core:

    I've not heard of any smelly foam core. That said, I would call up someone that you might know that has a gas sniffer and if you have a Digital Analyzer or a personal CO detector, I would check the atmosphere cor CO and Nat. Gas or LPG. If the house is on  Septic System, the smell of anaerobic bacteria can be rather overwhelming. If it is windy, and the leach field isn't vented on its own but vented through the tank, it will come through the outside stack and you can't stand down wind with throwing up. They have a special charcoal filter to put over the vent pipe. It is called a "Sweet-Aire". It still isn't. A good place to look that is overlooked is toilet seals. There are many who insist on using the expensive bowl extending waxes on  regular toilets. With PVC flanges, there isn't enough seal between the flange and bowl for the wax. It will leak air there. That spot you smell, may be where the smell is going to get outside, especially if it is on the lee side or down wind side. I never use those "extending" wax but everyone everyone I see uses them.

    I had a call to look at a leaking check valve on a fire sprinkler system. I walked in to the worst rotten smell in the cellar. It was either Mercaptan in the LP Gas, CO from gas appliances or a dead animal. It wasn't CO by my meter. I borrowed a Gas Detector and it was gas. A piece of CSST that had been placed over an old I-Beam that the vibration of the earth had worn a hole in the tube. Mercaptan is an odorant that is put in gas to make it stink. A recent fault in a manufacturing plant outside of Paris, France, stunk up the coast of England.

    I've put Sweet-Aires on vents where you couldn't sit on a deck, out of the wind in the summer time because of the smell.
  • Often

    you can hear a breach in the sanitary system by running water at the furthest fixture and then listening for the sound around the house.  Otherwise as Paul says, a smoke test.

    The source of a smell is hard to find.  I've been stumped many times.
    Often wrong, never in doubt.

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  • icesailoricesailor Posts: 7,265Member
    Smoke Test:

    Smoke will work. Its a project. Try a big bottle of peppermint Extract. Pour it down the stack. While up there, see what the vent gas smells like. If it is as overpowering up there as it is in the house, it's sewer. Municipal sewer odor is more like dirty laundry detergent and dirty washed clothes. A private disposal system (Septic tank) smells more like Mercaptan in gas, rotten eggs, worse than any bad rear end odor. Except for Kale Soup. As bad as Kale Soup gas. Sometimes worse though.

    It is worse if it is a newer leach field system with trenches for disposal rather than the old pits.

  • Paul48Paul48 Posts: 4,492Member
    One thing

    I've heard about peppermint, is, the person pouring the peppermint has to stay out of the house.
  • icesailoricesailor Posts: 7,265Member
    Pouring Peppermint:

    I've heard that. If the pourer goes down to the place of odor and takes a few deep whiffs, he will reset his sniffer right pronto by golly. Or else, he isn't the one to be doing the sniffing. Actually, I think that that fact approaches an urban legend.

    Maybe someone has a sewer sniffing dog.
  • Larry WeingartenLarry Weingarten Posts: 1,671Member
    Three things

    Thing #1.  Make sure that any closets are true closets and not converted from showers.

    Thing #2.  Hope nothing crawled into a wall and died.

    Thing #3.  Pour bleach down any  nearby shower drains.  They can make you gag sometimes.

    Yours,  Larry
  • kcoppkcopp Posts: 3,412Member
    It is on a septic...

    No changes / remodeling done. All the traps have water in them.

    This has been a problem for them for well over a year. The HO is convinced the former owners sold the house because of the smell.

    Very strong odor along this one section of pipe.

    I have asked the homeowner to remove all the insulation in the section of the basement under the offending room. Hopefully something pops up.
  • SWEISWEI Posts: 7,356Member
    no bleach

    on a septic.  35% peroxide will work wonders, but pre-dilute and take it easy if there's old cast iron involved.
  • RobGRobG Posts: 1,850Member
    edited January 2013
    Floor drain?

    I've had a couple of houses where a miss-piped floor drain got carpeted over. Also one where a miss-piped basement bath rough in pipe (no trap) got cut off by the carpet guys and carpeted over, on that one the only time it smelled was when the pumping station for the community kicked on. I've also had test tees drywalled over prior to the plug being installed.

    Good luck

  • Steve WhitbeckSteve Whitbeck Posts: 669Member

    Years ago I had a problem with the sewer smell.

    Turned out the garage was on the east end of the house and on a windy day with the wind out of the west the house would stink.

    found that the homeowner had not properly sealed the door between the house and the garage and the wind passing past the garage was causing a negative pressure inside the garage and thus the house via the leaky house door. This caused a downdraft of the fireplace chimney that was downwind of a sewer roof vent.

    Sealed the door - problem solved.
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