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WINT142000
Sewer gas around sewer clean out plug

With this being my second post in plumbing in two days, you can guess what is my weakness!

I've posted before about sewer gas coming in around the main clean out plug in our basement. I had that fixed when a plumber was here for another project back in September. The problems came back in early December and the smell is driving me nuts again. We've had delivery people come in and think we have a natural gas issue in the house.

I am not sure what exactly is the problem (PLEASE Help!), but to temporarily solve the issue, I put a plastic bag over the drain line cleanout plug and used duct tape to seal it as air tight as I could. Within a short period of time the bag inflated under the tape. I can push on it and air hisses out around the tape, and then the bag reinflated.

Questions:

1. Why would there be positive pressure in the sewer line heading out through the basement floor vs the unfinished basement?

2. I believe when the plumber was here he used plumbers putty to try to seal the cleanout cover. It worked for a while and then got worse again. How can I seal this in a more reliable manner?

3. Does this pressure gradient indicate that there is some other problem going on in my sewer system?

ANY advice would be greatly appreciated!!!

dj1
Re: Sewer gas around sewer clean out plug

Call your plumber again and ask him to check your vent for leaves, branches and other things that might block it.

A. Spruce
Re: Sewer gas around sewer clean out plug

I agree with DJ, sounds like a venting issue, as the sewer line should not be pressurized.

Fencepost
Re: Sewer gas around sewer clean out plug

Do you ever hear your drains burp? That indicates a blocked vent.

HoustonRemodeler
Re: Sewer gas around sewer clean out plug

Do any of the drain gurgle?

There should be no pressure nor vacuum on the sewer lines. You've got another problem. This is a symptom.

WINT142000
Re: Sewer gas around sewer clean out plug

Thanks for the info! I will try to trouble shoot this one. Being 6 degrees up in Michigan right now and 8 inches of snow in the last 36 hours, I am guessing no one will be climbing on my roof any time soon to check the vent!

HoustonRemodeler
Re: Sewer gas around sewer clean out plug

A frozen (ice blocked), too short, pipe may be the problem. Think about ice when the snow has melted and its safe to walk on the roof.

Sometimes animals seek out the heat / warmth of a vent line. Look for claw and teeth marks too.

WINT142000
Re: Sewer gas around sewer clean out plug

Think I figured it out! We resealed all the cleanouts in the basement and when doing a walk around, noticed that a mechanical vent in the 1/2 bath was not taped and even loose on the vent pipe. That was corrected so we'll see if that was the issue, but I think that you guys might have been right - maybe a venting issue in part and the sewer gas likely was leaking around that vent.

keith3267
Re: Sewer gas around sewer clean out plug

Have you checked with your neighbors to see if they have the same problem or are you on a septic tank. If you are on a septic tank, I can see this being a vent problem but if you are on a public sewer system, there may be a problem with their system.

There should be some positive pressure in a sewer system though. sewers and septic tanks generate Hydrogen Sulfide gas, which is heavier than air. In a working system, this gas will fill all the way to the top of the vents so that lower down in the system the pressure from the heavier gas will be a little greater then atmospheric pressure. You need a good tight seal around the cleanout plug.

WINT142000
Re: Sewer gas around sewer clean out plug

I'm on city water/sewer. I don't know if my neighbors are having any problems; I haven't asked. A stinky house is a bit of an embarrassing subject!

The plug is resealed as well as the mechanical vent has been re-installed properly, so I hope that our problems have been fixed!!!

Again, thanks for the reply!

keith3267
Re: Sewer gas around sewer clean out plug
WINT142000 wrote:

I'm on city water/sewer. I don't know if my neighbors are having any problems; I haven't asked. A stinky house is a bit of an embarrassing subject!

The plug is resealed as well as the mechanical vent has been re-installed properly, so I hope that our problems have been fixed!!!

Again, thanks for the reply!

It would be a shame if the city sewer system had a problem and it didn't get fixed because everyone was too embarrassed to talk about it.

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