Bathroom sink smell - what's wrong? (Photo)

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Pshack, Aug 24, 2019.

  1. Pshack

    Pshack New Member

    Joined:
    Aug 24, 2019
    Location:
    Ottawa
    I recently had my bathroom sink converted to a double sink vanity and ever since there is a sewer gas smell from the sinks (one sink more than the other).

    I have included a picture of my setup, what is wrong?

    I even had a 'cheater' vent added to give more air to the system. The traps appear to be full of water, I can't figure it out. Any thoughts?https://photos.app.goo.gl/5kH9fiAXCZkhg9h48
     

    Attached Files:

  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    You have an S trap, and the AAV is not venting the right place. See https://terrylove.com/forums/index.php?threads/p-trap-install-stubs-out-too-low.68736/

    That may not be the cause of the smell, however. Lavatories usually drain fairly slowly, so an S trap may not cause a smell in practice. To work around the S trap, make sure that you end your lavatory use with a low flow that will not cause siphoning.

    A fix would require dealing with glued joints, so it would be difficult to make that right. I suggest that you put a plastic bag over your AAV as a test, and secure the bottom with tape or rubber band. See if the smell stops. If so, the AAV is leaking. Your AAV is not doing anything useful where it is anyway. I am not a plumber.

    [​IMG]
     
    cjlambert likes this.
  3. Sponsor

    Sponsor Paid Advertisement

     
    cjlambert likes this.
  4. Pshack

    Pshack New Member

    Joined:
    Aug 24, 2019
    Location:
    Ottawa

    The AAV was actually added after the fact. I put up with the smell for 2 months, wondering how to solve it and all I could come up with was adding an AAV to bring more air into the setup.

    It doesn't appear to be working (although if you are saying it's not installed correctly - it's probably not much help)

    I can cover the AAV, but that would effectively return my setup to what it was before....which allowed gases to get through.

    Appreciate the input.

    Peter
     
  5. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Cover the sink with plastic to make sure that the smell is coming from the sink. Make sure the smell is stronger under the plastic sheet. A cheap plastic dropcloth is good to help locate the smell.

    If the smell is coming from the sink, it could be from stagnant water growing something in the overflow paths. Maybe treat with bleach to see if that improves the smell. See https://terrylove.com/forums/index.php?threads/faucet-question-drain-waste-seat.83005/#post-598504

    Don't get me wrong. An S-trap can cause sewer gasses to come through the siphoned trap. But when you go slow enough on the flow, even an S-trap will stop the sewer gasses.
     
  6. Pshack

    Pshack New Member

    Joined:
    Aug 24, 2019
    Location:
    Ottawa
    I'm dissappointed to have to ressurect this thread. I cut the pipe on the sink that was causing most of the smell (the one with the "s-trap" and found that it was full of water. I was hoping to find it empty so that it would give a good reason why the sink smells. I stuffed a rag in the pipe and went a couple of months using just the one sink. Although it wasn't as bad, the smell did continue and I could source to the one functional sink. In the end I had my two sink setup replumbed so that each were properly vented and so they both have a proper p-trap. Unfortunately the smell is still there!

    I am really at a loss (I know my wallet is that's for sure). I figue if I had it properly replumbed all would be solved. What could possible explain the smell? It is without a doubt coming from the drain (and particulrly the overflow). The vanity I bought is new, so I can't imagine that anything is growing in there or that ther blocked in anyway. The pipes are all brand new as well. The smell is without a doubt a sewage smell.

    Is it possible that the sewer gas is getting past a "functioning" p-trap?

    What do I do?
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Are you confident the smell is from the bad sink bowl? Try covering that lavatory top with thin plastic, such as a plastic drop cloth. After time, make sure the smell is much worse under the plastic than above.

    So where do things sit? Is the tailpiece of the bad sink connected to the s-trap, or has that been disconnected?

    Edit: an S-trap should work if you always end with water at a low flow, which refills the trap if it siphoned.
     
    Last edited: Jan 30, 2020
  8. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    It could be a bad AAV. Though if the smell was bad before it was installed, maybe that's not it.
    Have you flushed down the overflow on the sink. Bad stuff can hang in there.
    Seal on a toilet bowl gone bad?
    Do you have any critters like mice? They can make a mess.
     
Similar Threads: Bathroom sink
Forum Title Date
Plumbing Forum, Professional & DIY Advice Bathroom Sink Drain Run Today at 5:15 AM
Plumbing Forum, Professional & DIY Advice New Sink for Bathroom Monday at 4:35 PM
Plumbing Forum, Professional & DIY Advice Bathroom sink replacement - off-center from drain Sunday at 10:46 AM
Plumbing Forum, Professional & DIY Advice Bathroom Double Sink Vanity plumbing question/issue Saturday at 6:01 PM
Plumbing Forum, Professional & DIY Advice Bathroom Sink Won't Drain Mar 31, 2020

Share This Page