New bathroom has sewer smell and drain flies -- WHY???

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by krystal, Mar 3, 2009.

  1. krystal

    krystal New Member

    Mar 3, 2009
    Toilet, sink, and tub were roughed in about 5 weeks ago in basement; brand new pipes throughout basement. Sink, toilet, and tub are now fully installed. There has been a problem with drain flies from almost day one, as well as a sewer smell. We put a rag in the tub drain, and many fewer flies, but still a smell. Any suggestions? Are we going to need to rip apart the brand new bathroom walls and floors to figure this out?
  2. kingsotall

    kingsotall Plunger/TurdPuncher

    Aug 17, 2008
    Hand copper part cleaned ready to go
    Flagstaff, AZ Sitting on an upside down 5 gallon b
    Do you have any pics of the rough in process¿
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  4. seaofnames

    seaofnames DIY Senior Member

    Jan 25, 2009
    Mission, BC
    Sounds like someone forgot some glue in a drain connection or to tighten something down.

    Could be a lack of a trap under the tub?

    Like kingsotall said, pics would be good of the rough in!!
  5. 3m

    3m New Member

    Mar 3, 2009
    Most people can smell sewer gas and by going to the different fixtures figure out where the smell is coming from. If this fails you can take a combustible gas detector, I know not everybody has one so you may need to contact a plumber or heat and air man and they can detect where the smell is coming from. Sewer gas has methane in it so the detector will show where its at most of the time, I have seen the wax ring fail and allow gas in under the toilet.If its coming from the tub drain they either forgot the trap or the vent and its sucking the trap dry, if the bathroom isnt used much it may just be the water evaporating out of the trap
  6. Cass

    Cass Plumber

    Nov 12, 2005
    post pics of the drain lines that are under the floor...
  7. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    Pics will help, but there is only one way sewer odor and drain flies can get into the house. Somewhere there is a dry trap or no trap.
  8. Jay Mpls

    Jay Mpls Master plumber

    Sep 29, 2008
    Master Plumber /Sewer rat
    Sewer flies only come from satnding water so I believe you have an open pipe draining waste onto the ground.
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