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  1. #1
    Join Date
    Jan 2008
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    4

    Default sewer gas in house

    I'm having a problem with sewer gas venting into the house. We can't determine where the gas is originating except from the basement. It comes mostly from using alot of water at one time. Such as: 2 showers and 3 wash loads. The smell is at it's worst when the wind is from the South and West (vent is on the W slope of the roof). We have a septic system and the house is 30 yrs old. This has been an on going problem since we built. We recently had the basement permasealed with an enclosed sump pump. The smell was much better a year ago when the basement was sealed for leaks in the foundation but now the odor is back.

    I have a septic system but don't have any issue with the drains not draining. I was going to have the septic pumped but the septic company said they didn't smell anything when they opened the cap. We can't figure why it's a problem and why it is worse when there is a South/West. Any ideas??
    Last edited by laguna1; 01-18-2008 at 01:19 PM.

  2. #2

    Default Re: sewer gas in house

    check your vents

  3. #3

    Unhappy Re: sewer gas in house

    We also have sewer gas smells in our house, especially after a heavy rain. We have had the septic system pumped and we checked the vent. Still we have that smell every once in a while. Sometimes if the toilet is flushed right before a shower is taken, the toilet bubbles and gurgles until the shower is cut off. our house was built sometime in the 70's. everyone we have asked doesn't seem to know why. Is there anyone out there who does know?

  4. #4
    Join Date
    Aug 2007
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    612

    Default Re: sewer gas in house

    jjthompson....A couple ideas for you....
    I would check to make sure your vent stack is clear. The fact that when you shut off your shower it allows the toilet to flush properly points me in that direction. You may want to check that a proper vent was used for the shower / toilet in that bathroom to begin with. Sometimes construction / remodel efforts may have taken a short cut or two!

    If you have the bubble / gurgle problem when you flush a couple times in a row without the shower on, it may be a slow drain from that bathroom not allowing the water to clear out of the drain pipe fast enough. The drain pipe itself may be clogged or the problem may be all the way out at the septic tank (clogged exit port) or your drain field is clogged (solids in drain field).

    We had to have a new drain field dug two years ago (big $) when ours failed. If you can get the lid off your septic tank and watch the inlet side when the toilet is flushed you should be able to tell if a good amount of water is pouring in at once (open drain pipe) or if it is coming in a trickle (clogged drain pipe).

    You may be able to tell if the exit port of the tank or the drain field is clogged by how high the water level is in the tank. If it is at the inlet port height (like ours was) then the exit port / drain field is probably the problem. The level should be below the inlet port far enough so that you can hear/see the water dropping into the tank.

    Start with the easy checks first to eliminate possible problems. Hope this helps.

  5. #5
    Join Date
    Aug 2007
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    612

    Default Re: sewer gas in house

    Laguna1 - Do you have any dampness on the wall where the soil pipe exits the basement wall on the way to the septic tank?

  6. #6
    Join Date
    Jan 2008
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    4

    Default Re: sewer gas in house

    I had the septic people out to pump and he didn't notice any leakage at the foundation. He couldn't pump that day because the wrong lid was uncovered. We have dropped a plumb from the roof stack to check for any blockage.

  7. #7
    Join Date
    Aug 2007
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    612

    Default Re: sewer gas in house

    Quote Originally Posted by laguna1 View Post
    I had the septic people out to pump and he didn't notice any leakage at the foundation. He couldn't pump that day because the wrong lid was uncovered. We have dropped a plumb from the roof stack to check for any blockage.
    So how many lids do you have on your tank??

    Not that this narrows it down any, but others have posted on here about noticing sewer gas when wind comes from a specific direction. If I remember correctly, those problems usually came down to a bad wax seal on a toilet. It seems the air pressure against the vent system changed just enough with the change in wind to allow the odor.

    Some other quick ideas....
    Is your washer in the basement and does it have a trap somewhere on the drain pipe it uses (I am assuming the drain hose is just hooked into a vertical drain pipe)?

    Is your soil pipe accessible in the basement and could it have any cracks at fittings on the top of the joint? (water wouldn't get out, but gas would)

  8. #8
    Join Date
    Jan 2008
    Posts
    4

    Default Re: sewer gas in house

    We have I think 3 lids on the tank and we do have an elbow on the washer. We have a soil pipe in basement but have not checked there for cracks we will investigate. Smell seems to be coming from the sump but there is no evidence of sewage in there and no leaking water of any sort.

  9. #9
    Join Date
    Jan 2008
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    4

    Default Re: sewer gas in house

    I have checked the soil pipe and no evidence of cracks. Sewer gas is getting worse with less water usuage. Have had extreme cold weather lately. The only help to relieve the smell is to run water in the sump and recir. the filter bed tank ( use for removal of sulfur).

  10. #10
    Join Date
    Jan 2010
    Posts
    163

    Default Re: sewer gas in house

    Quote Originally Posted by laguna1 View Post
    I'm having a problem with sewer gas venting into the house. We can't determine where the gas is originating except from the basement. It comes mostly from using alot of water at one time. Such as: 2 showers and 3 wash loads. The smell is at it's worst when the wind is from the South and West (vent is on the W slope of the roof). We have a septic system and the house is 30 yrs old. This has been an on going problem since we built. We recently had the basement permasealed with an enclosed sump pump. The smell was much better a year ago when the basement was sealed for leaks in the foundation but now the odor is back.
    Sewer gas smells almost always come from a lost trap seal somewhere in the system. They hardly ever come from some kind of leak in the drain system, and if they do, you would see dripping water at that leak. This includes the wax seal on the base of the toilet.

    Traps need to be protected from siphoning (negative pressure) or from burping (positive pressure) by properly placed vents.

    In your case, the smell usually follows heavy use of the plumbing--the reason is probably because heavy use fills the drains more, thereby creating pressure fluctuations in the system, with the potential to siphon traps, or cause them to burp. (Siphoning is more likely the problem.) Wind direction can also affect whether or not a trap whose water seal has been lost gives off sewer gas, because wind can affect pressures within the system, but wind, by itself, would not siphon a trap.

    You can isolate/identify which trap is causing the trouble:
    On a day when you notice the smell, go to the lowest cleanout in the house and remove the plug; pour in a small bottle of peppermint oil and replace the plug; close all windows and doors; turn on all exhaust fans in the house, including the clothes dryer and range hood--you are aiming to de-pressurize the house as much as possible. Now, go around to each drain opening and sniff for peppermint.

    The trap(s) that smell strong have lost their seal, and have a problem with a vent that should be protecting them from pressure fluctuations. How to fix the vent is another problem, but at least you will know the culprit. In some cases,the fix can be as easy as installing an Air Admittance Valve at the fixture that is causing the trouble.

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