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Skidder 01-11-2012 06:28 PM

Septic Tank Smell - Interior
Hi There,

I'm new here and have been trying to figure out my plumbing issue for a while now. We just moved into a new (100 year old) house with a septic system. It's my first experience with a septic system so please bear with me.
We had it pumped 3 months ago when we moved in, but there is still a septic gas smell in the back room whenever the bathroom or kitchen taps are running, or when we flush the toilet or do laundry (Basically whenever water is draining out.)

The house is small -1000SF slab on grade foundation with a VERY tight (12" or less high) crawlspace area underneath the laundry room/bath area. We can see the drain pipes from the laundry room run into the floor and the vent stack is nearby on the exterior wall enclosed in an unheated shed attached the back of the house.
I tried running the hose into the vent stack to unclog it but that did nothing for the smell. The bathtub and sinks have no problem draining, no gurgling, they just cause that disgusting smell to come out near the laundry room (now renamed the poop room) drain pipes.
The washing machine looks very new and there is no visible mold inside, so I'm pretty sure this is a venting issue but I'm not sure how to fix it as the pipes are under the floor and hard to access without ripping up the current floor which I'd like to avoid if possible. I've read about small air-intake vents that can be attached to the drain pipes to help vent but I'm not sure if this will work in this case.

Any advice? Thanks!

phishfood 01-12-2012 12:37 AM

Can you see the drainage piping for the laundry, or is it enclosed in a wall? If you can see it, can you attach a picture?

Skidder 01-13-2012 07:28 PM

HI Phishfood,

I am still figuring out how to upload a photo to this forum. In the meantime I'll try to explain: The drain hose from the laundry is hooked onto an exposed drain pipe that is about 3 feet tall, strapped to the wall and then slopes through the wall into the adjacent room at about a 35 degree angle and then into the floor. Hope this helps.

Skidder 01-13-2012 08:29 PM

Photos up in the photo album i just uploaded. thx

havasu 01-14-2012 05:30 AM

3 Attachment(s)
I'll make this a lot easier.

phishfood 01-14-2012 12:36 PM

Is there a trap behind the plywood in the first photo?

If not, is there a trap underneath in the crawl space?

There needs to be a trap somewhere in that drain line, to prevent the sewer gas from being pushed out when another fixture drains water.

Skidder 01-24-2012 09:45 PM

Yes, there is a trap behind the plywood for the laundry drain.
The smell seems to be emanating from below the floor where the pipe drains down to and the supply pipes come up. The previous owner had sprayfoamed around the openings in the floor. We thought it was for insulation purposes but maybe it was to block the smell.

LeakFinder 02-10-2012 12:56 PM

You may need to put some more foam back if after you removed it you are experiencing the smell.

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