Rough plumbing = sewer gas

Discussion in 'Remodel Forum & Blog' started by mattt19, Mar 12, 2008.

  1. mattt19

    mattt19 New Member

    Messages:
    33
    The rough plumbing has just been completed for my bath remodel. The vent stack for this bath is shared with an adjacent bathroom. A day after the rough plumbing was completed I could smell sewer gas coming out of the adjacent bathroom's sink. The drain lines in the remodeled bath had rags stuffed into the open drain lines. I placed plastic bags over the open drains and taped them on. This appeared to take care of the problem. Now a week later the smell is back. I've left a message with the plumber. Does anyone have an idea why I would be smelling sewer gas?
  2. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Without seeing what was done and in what condition/stage that the project was left at, there is no way to tell. The traps may be drying out or empty or you have not sealed/capped one of the pipes adequetly.
  3. mattt19

    mattt19 New Member

    Messages:
    33
    The entire bathroom was re-plumbed. The toilet, vanity and tub were all moved. New water lines and drain lines were installed. At this stage the plumber is waiting for all the finish work to be completed (tile, drywall...) How would you even go about determining what is causing the problem? Would a hole in a pipe cause this? I rechecked the pipes and they all appear sealed tightly. I only smell this in the adjacent bathroom. This bathroom is used on a daily basis so there should be water in the traps.
    This problem comes and goes. This morning I could smell it, now I don't. There isn't a predictable pattern to when it smells or not. It's random.
  4. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Thats very possible. A cracked fitting may very well be a problem. It usually happens with ABS fittings. I haven't come across any pvc doing this


    If you have a shower in the new bathroom, check the drain for the shower and see if the trap is full of water.


    Just a thought off the wall. I had an incident where a strange odour was comming from a clients bathroom. It turned out to be the wiring in a pot light when it started heating up. It wasn't melting or anything like that, but it was a concern , enough to replace the pot light.
  5. AZ Contractor

    AZ Contractor In the Trades

    Messages:
    90
    Location:
    Phoenix, AZ
    It sounds like it could be incorrectly vented and its causing the trap to be siphoned dry.
  6. mattt19

    mattt19 New Member

    Messages:
    33
    The plumber stopped by today but couldn't find anything wrong. There are no traps yet in the new bathroom. Just the rough drain lines. These are sealed.
    If it was incorrectly vented, causing the traps to be siphoned dry, wouldn't the trap always be dry? He's been a plumber for 40 years so I hope he vented it correctly.
    If there is a cracked fitting how would I find it? He checked all the fittings and said they looked OK. Could I pour water through the drains and see if any of the fittings leaked?
    Hopefully I can solve this before the floor goes down and the walls are sealed up.
  7. crater

    crater New Member

    Messages:
    49
    Are the drains that you have covered with plastic bags the stub-in's or actual drains like the tub or shower?
    If they are in use, then there should be traps for them, and if the gas is coming from them, then you have some incorrect plumbing, something like the toilet is flushing past the drain pulling the water out of the trap. If there just stub's, then you can buy cheap knock out plugs that you glue into the pvc, that should stop gas from coming in. I saw a coupling once that wasn't glued. We as a quick fix (not permanant) sopped the exterior of the joints with pvc glue, when we fixed for good we had to cut out the couple and replace with a rubber coupling, it was a pain in the rear.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    drains

    After he installed the piping it should have been tested with a head of water to ensure that there were no leaks or bad fittings. Odors are the hardest problem to diagnose because they can originate a long way from where you have the problem.
  9. mattt19

    mattt19 New Member

    Messages:
    33
    They're stub-in's. The problem (the smell) isn't in the bathroom that's under construction. The smell is coming from the sink in the adjacent bathroom. Prior to this there wasn't a smell. It's only the sink that smells periodically. The shower and toilet in the same room don't.

    "After he installed the piping it should have been tested with a head of water to ensure that there were no leaks or bad fittings."

    The pipes were tested but not the drain lines ( is that what you mean?)
  10. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    If the trap is fine, I'm going to bet that the sink overflow/P.O. plug is filled with gunk. I've been told that some baking soda and vinigar may help clean that smell up. (I've never tried that myself)
  11. mattt19

    mattt19 New Member

    Messages:
    33
    Thanks,

    I'll try that
  12. mattt19

    mattt19 New Member

    Messages:
    33
    Well, the smell is back. When the plumber checked the pipes he also removed the stopper in the sink and cleaned out all the gunk that was attached to it. After that the smell went away and I assumed that was the problem. When the smell came back I tried using vinegar and baking soda as recommended. That didn't work. I can only smell the odor when water is running down the drain though my wife smells it at other times.
    The last time I smelled the odor I removed the trap. It was full of water.
    I'm posting pictures of the sink and the plumbing.


    Thanks,

    Matt

    Attached Files:

  13. you are ok

    it looks ok, a little sloppy but
    it will work for a hundred years...

    what probably happenned to you is
    most likely during construction some long hair or string
    or debris got stuck half way around that sink trap

    and when this happens , it has atendencey to
    act like a siphon hose and literaly drain that trap dry..

    its really no big deal, it happens a lot
    so occasionally you might
    want to pour some boiling water down that
    sink to loosen debris out of it...
  14. Terry

    Terry Administrator Staff Member

    Messages:
    15,419
    Location:
    Bothell, Washington
    A little sloppy waste and vents?
    That work looks like someone that just opened a book for the first time and couldn't understand it.

    The trap arm for the lav should go up at a 2% rise, or 1/4" per foot.
    He has raised it with fittings, creating an "S" trap what will siphon the trap dry.
  15. mattt19

    mattt19 New Member

    Messages:
    33
    Hi Terry,

    Which part is the trap arm? Is it the chrome piece leading from the trap to the wall? I put a level on it and it is angled up (maybe the angle of the photo looks like it's not). If the trap itself is on incorrect that would be my fault. I took it off to see if there was water in the trap.
    I don't know anything about the quality of the work. He did do the plumbing for the sink in the first picture. He had to tie into the existing system. In the picture with the exposed plumbing, there had been a sink in this area which he had to work around when doing the plumbing for the first sink. There are also a number of pipes under the wall in this area including a gas line that couldn't be moved. I don't know if any of this contributed to the quality of the work. Are there any obvious problems that I should have corrected? Or is it just the case of sloppy work that looks bad but will function fine.
    I'm open to recommendations if anyone can recommend a good plumber in Los Angeles.

    Thanks,

    Matt
  16. Terry

    Terry Administrator Staff Member

    Messages:
    15,419
    Location:
    Bothell, Washington
    Matt,
    In the picture of the black pipes, you have it labeled "sink drain".
    That pipe should be straight, and the santee raised.

    Attached Files:

    Last edited: Apr 12, 2008
  17. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Your sink drain needs to be redone more like the pink lines I drew over your picture. The pitch should be 1/4" per foot. Going the way he has it made an s-trap which is illegal.

    [​IMG]
  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    "S" trap

    IT is not only illegal but it will siphon itself when the water flow is just right. He must have forgotten what he learned in his first week after 40 years.
  19. mattt19

    mattt19 New Member

    Messages:
    33
    Hi everyone,

    Thanks for the information. It's not what I wanted to hear. I'm having real doubts about the plumber because of this. He's had two chances to catch it and missed it both times.
    In his defense, I don't know if he installed this section of plumbing or if it was existing. It's possible he just hooked the sink to it. There had been a sink there previously so it's possible someone else did this. Why he didn't notice it I don't know. The bathroom was gutted down to the studs so he should have seen it. It certainly explains the sewer smell. If I have him fix it, in your opinion, whose responsibility is it? Should I be expected to pay for it?
    If I fix it, I have a couple questions. I'd cut the pipe at 1,2 and 3 and remove the S. At # 1 I'd be left with 2 1/2" of pipe. I'd attach a coupling to this and then a length of pipe that would run to a new sanity tee. The pipe would pitch down 1/4" from point #1 to where it connected to the sanitary tee. The tee would be installed on the drain/vent pipe. What is the flange on the pipe at #2. Do I need this?

    Thanks

    Attached Files:

  20. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    The flange part at #2 is a reducing bushing (2"x 1 1/2"). I can't judge the exact sizes, but it looks like a 2x2x1 1/2 sani T with bushings to reduce to the appropriate sizes. Your branch to the sink looks like 1 1/4" . This drain looks like its wet venting the toilet drain.

    You will need a 2x1 1/2 x 1 1/4 sanitary T (or facsimilie)
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