Kitchen sink drain / trap / vent issue. Sewer smell, glug glug, etc.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by contactcr, Oct 4, 2013.

  1. contactcr

    contactcr #oldhouseproblems

    Messages:
    4
    Location:
    Texas
    Background:

    Kitchen sink with two sink basins. Dishwasher hooked into garbage disposal on right side.

    No issues with drains, smells, traps, etc in any other parts of the house as far as I have noticed.

    We primarily get the sewer gas smell when emptying a large pot or doing a lot of dishes commonly combined with using disposal. You can sometimes hear the left sink spit up right after using disposal and that's when the smell is worst. Under just normal use the sink will sometimes make the glug glug sound when draining and sometimes not.

    I'm thinking since there are two P traps the volume of water and the disposal is sucking the water out of the second trap but i'm not sure if it's plumbed wrong and should have just one trap or I have a secondary issue with the vent. There are a few vents in the back of my house but nothing above the kitchen so i'm not sure how this drain ties in. House built in '86 and none of the houses in the neighborhood have vent stacks in the front so I assume everything vents to the back so it looks better from the outside.

    Pictures:

    TOP VIEW
    20131002_131149.jpg

    BOTTOM VIEW
    20131002_131128.jpg

    SIDE VIEW
    20131002_130941.jpg
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    Your description indicates that the MAY be a problem with the piping inside the wall, but the pictures do NOT give us any indication as to whether that is the case or not.
  3. contactcr

    contactcr #oldhouseproblems

    Messages:
    4
    Location:
    Texas
    Any tests I can rig up or additional info I may be able to provide for a more definitive answer?

    Also, I was under the impression two P-traps going into one drain was not ideal since it is possible one can be siphoned empty. We only really use the side of the sink with the disposal and the other side is primarily just used for drying or to make room while washing dishes. However, I do still run water down that side just to be sure the trap is never dry.
  4. Smooky

    Smooky Member

    Messages:
    624
    Location:
    NC
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    As for whether it is ideal or not, I sometimes use THREE traps for a three compartment kitchen sink, since the middle one is usually shallow for a disposer and it is cumbersome to try to connect any two sinks together, much less all three, into a single trap.
  6. contactcr

    contactcr #oldhouseproblems

    Messages:
    4
    Location:
    Texas
    So a plumber came out and we are pretty confident we found the vent in the attic. Also, the sink drains pretty fast so it's likely there IS a vent. His only suggestion was to redo the drain with a single trap at a HEFTY expense. I didn't get the feeling this was a definite solution and at the price quoted i'd want to be sure.

    Again, the problem typically happens when running the water for a while and/or using the disposer. Sounds like suction is created, pulls water from other trap and brings a god awful smell up with it in the unused sink basin. Also, after running the water for a period of time after it's done draining you can hear 'glug glug glug' for 10-15s frequently (but not always?)
  7. Reach4

    Reach4 Well-Known Member

    Messages:
    2,401
    Location:
    IL
    1. Rig up? I have an idea for measuring the pressure at the far side of the P trap under the sink. Get about 6 to 10 feet of clear plastic tubing. Old oxygen tubing would be good for this if it is small enough to get through the drain. Push one end of the tubing down the sink drain about 2 or 3 feet. That will move the tip through the trap to the other side. Blow the free end hard to blow out any water. Put the free end into a glass of water and push to near the bottom of the glass. Rig something to hold the tube.... Note how high in the free end of the tube the water level goes. Ideally, it will be at the same level as the water in the glass. Drain the other bowl. If the air level in the tube is lower than the level in the glass, measure the difference as best you can. Keep it there for a while, and note changes when you operate various plumbing. If the level changes more than an inch, that would seem significant.

    2. To work around this, after emptying a big load of water down the drain, run about a cup of water down the smelly drain to refill its trap.

    I am not a pro.
  8. contactcr

    contactcr #oldhouseproblems

    Messages:
    4
    Location:
    Texas
    I do run water down the other sink when it spits up and smells but that is all after the fact. I'm trying to avoid the initial smell, I am not worried about the trap getting bone dry.
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