Main vent pipe/sewer smell

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by potterboy1, May 6, 2011.

  1. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    I have a septic tank system and sometimes when I am outside I can smell sewage but it seems to depend on which way the wind is blowing. The main vent pipe is on the backside roof of the 2 story house. The septic tank is also on the same side of the house as the vent. So I can't tell if the smell is coming from a septic tank issue or the vent pipe. I was wondering if I can put a one way vent cap on the vent pipe? So that air can come into the vent but the stink can't come out. I am in the northeast and we have had a lot of rain lately, granted not as much as Seattle but close, can the smell come through the wet ground? I know that the lid to the septic tank is just below the sod. The lid is on a cement riser.
    Thanks All
  2. Smooky

    Smooky Member

    Messages:
    624
    Location:
    NC
    I had this same problem. I installed an Air Admittance Valve (AAV) on the top of the 4 inch vent on the roof that is over the bathroom. I do have another vent that was not causing any odor problems, so the septic system can still vent out. The AAV allows air to go into the vent but does not allow it to come out. They are used inside of buildings instead of cutting holes through the roof or where you do not want the vent to show. When I was picking it out at Lowe's the salesman said it was not approved to be used outdoors. He said it would deteriorate and not hold up in the sun. He also said that condensation might form inside and cause it to freeze, but that has not been a problem for me. When it deteriorates I will saw it off and put on another one. It has been up there for twelve years. There is a plastic screen around the edge that has started to fall apart. It has worked and there have been no odors at the back door or on my patio since I installed it. Mine is a Studor vent.
  3. Cookie

    Cookie .

    Messages:
    5,658
    Location:
    .
    No you can't put a one-way vent cap on as air pressure needs to be both postive & negative. ( in and out) In regards to the smell coming through the leachfield (ground) it is possible; how old is your leachfield?
  4. Cookie

    Cookie .

    Messages:
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    No code that I know of approves AAV on a main vent of your house.
  5. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    I don't know how old the leech-field is. We have been in this house for about 13 years. According to the house plans the field goes out into the woods but I don't see any wet ground out there and it doesn't seem to smell out there.
    Thanks
  6. Smooky

    Smooky Member

    Messages:
    624
    Location:
    NC
    There is a Studor vent that is approved for outside, it is called the Tec Vent . I do not have it on my home. Mine is approved for indoor only but it has solved my problem. My septic system can still vent through the other roof vents. The vent I put the Studor vent on is at the edge of the roof where my patio and back door is located.
  7. Cookie

    Cookie .

    Messages:
    5,658
    Location:
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    Regardless, of the fact that a manufacturer makes a Studor vent that can be used outdoors code does not permit its use. Unless, code permits its use, it is not allowed.
  8. Cookie

    Cookie .

    Messages:
    5,658
    Location:
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    How old is your home?
  9. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    I only have one vent for the whole system. Will the Studor/Tec Vent still be OK to use?
  10. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    The house was built in 1965. The septic tank is cement and the sewer and vent plumbing is ABS and PVC.
  11. Cookie

    Cookie .

    Messages:
    5,658
    Location:
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    Your leachfield may be the original and before you go breaking the plumbing code by putting on a Studor vent you need to figure out where the odor is coming from.

    When was the last time you had the tank pumped?
    Last edited: May 6, 2011
  12. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    It was pumped 5 years ago.
  13. Cookie

    Cookie .

    Messages:
    5,658
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    Might be time again.
  14. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    Planned on doing it this summer once the ground dries out.
  15. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    OK when I was outside today I checked all around where the septic and leach-field are and there was no smell. The only time I smelled the sewer it was near the vent pipe side of the house and where I could smell it depended on the wind. I am now more convinced that the smell is coming from the main ,and only, vent pipe. Will pumping the tank help? Could I put an extension on the vent pipe? It comes out of the roof on the second floor and it is about 2 feet long. Any more thoughts?
    Thanks Again.
  16. Smooky

    Smooky Member

    Messages:
    624
    Location:
    NC
    You could try a roof vent odor control filter. I do not know anything about them or how long they last.
  17. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,250
    Location:
    Land of Cheese
    Google "plumbing stack charcoal filter" and you will find that several products are available to treat your symptoms.
  18. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    Thanks I will give it a try and let you all know.
  19. potterboy1

    potterboy1 New Member

    Messages:
    20
    Location:
    NY
    Update to an old thread. I purchase one of those activated carbon filter vent caps. I still have both positive and negative air flow into my vent pipe but there is still the sewer odor when the ground is wet. I still haven't gotten the tank pumped. Is there a device in existence that can detect where the odor is coming from?
    Thanks
  20. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    What a terrible idea, putting an AAV on a roof vent.
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