Septic gas odor puzzle - HELP!

[WR Don]

Hi All,

There is a sewer gas odor that seems to come from nowhere. The problem started 2 years ago right after we bought the house. Previous owner said he had no problem and I believe him (there was no odor the 3 times we looked at the house prior to buying, and nobody would live with that for the 5 years they owned it).

The septic tank was pumped just prior to us moving in, so I suspect it has something to do with that, but I do not know what. House is only 7 years old, one story with 4 1/2 bathrooms. The odor is only in one BR and the attached bath. The bedroom at times seems worse than the bathroom.
The main waste drain to the tank exits the house under the problem bathroom, but the lawn outside shows absolutely no evidence of a septic tank leak

To save everyone a lot of typing, I regularly add water to all the bathroom fixtures that we don't use (kids are grown so we only use 1 1/2 bathrooms). With this ongoing problem, I got so frustrated that I completely removed the lav P-trap and sealed it at the wall, removed the WC on the odd chance the wax seal had a leak, plugged the bath overflow and filled the tub with water. Nothing worked.

Basically, there were no plumbing openings left in the bathroom, but the odor continued. I just had the septic tank company come over and do a smoke test (fan powered) on the odd chance that a vent fitting had not been glued and was coming loose, but absolutely no smoke was seen in the house, attic or crawl space. I also put a hose down the 3" vent serving the problem bathroom, and also saw no evidence of water in the attic, walls or crawl space

There is no odor in the attic space or the conditioned crawl space, or outside the house. Another head scratcher is that there is another bathroom on the ease side of the problem BR, and another bathroom on the east side of the problem bathroom. These also have absolutely no odors.

Also, there is no furnace to blow an odor from somewhere else (hot water heating), and water heater is tankless, so there is no floor drain in mech room. No AC so no condensate drain scabbing into plumbing vents.

I have even taped over the bathroom exhaust fan as I grasp at straws. There is no opening into either room that plumbers or I can find to let any gas into the rooms.

Does anybody have a crystal ball or even a wild arse guess as to what other possibilities might be causing this?

Thanks!

 

[Reach4]

I would close the door to the problem bathroom and bedroom for a few days. Maybe put a towel in the space under the doors. Then see which side of the bathroom door has the most smell.

 

[Sponsor]

 

[FullySprinklered]

Got a brain hernia trying to remember the circumstances, but I did have a customer quite a while back that had an odor problem. Turned out it was coming from nail holes in the pipe shot through the trim in a place that should have had nail plates to protect the pipe. You wanted wild arse.

 

[WR Don]

I would close the door to the problem bathroom and bedroom for a few days. Maybe put a towel in the space under the doors. Then see which side of the bathroom door has the most smell.

Did that (and still doing it). Odor is in both rooms., but not in the attached walk-in closet. Go figger... Thanks!

 

[WR Don]

Got a brain hernia trying to remember the circumstances, but I did have a customer quite a while back that had an odor problem. Turned out it was coming from nail holes in the pipe shot through the trim in a place that should have had nail plates to protect the pipe. You wanted wild arse.

Thanks Fullysprinklered. That was another WAG I had with an unglued fitting, althought there are no nail holes in the wall. Unfortunately, the smoke test showed nothing. If there are nail holes, the shoke should have gotten in the wall cavity. Unfortunately I don't know where the vents are or I would open the wall to look.

 

[FullySprinklered]

You've been very thorough; it's a tough one. Other things that may be seeking sources of air which could pull odors into the living space, would be your clothes dryer, range hood, gas-fired water heater. Also, I had a customer this year who's toilet never quite made contact with the wax ring, leaving the sewer open, but it never smelled bad. It took a downstream clog for him to discover this problem, causing a nasty overflow situation. Strange that it never stunk. Know anyone with a bloodhound?

 

[RickEG]

Hi All,

There is a sewer gas odor that seems to come from nowhere. The problem started 2 years ago right after we bought the house. Previous owner said he had no problem and I believe him (there was no odor the 3 times we looked at the house prior to buying, and nobody would live with that for the 5 years they owned it).

The septic tank was pumped just prior to us moving in, so I suspect it has something to do with that, but I do not know what. House is only 7 years old, one story with 4 1/2 bathrooms. The odor is only in one BR and the attached bath. The bedroom at times seems worse than the bathroom.
The main waste drain to the tank exits the house under the problem bathroom, but the lawn outside shows absolutely no evidence of a septic tank leak

To save everyone a lot of typing, I regularly add water to all the bathroom fixtures that we don't use (kids are grown so we only use 1 1/2 bathrooms). With this ongoing problem, I got so frustrated that I completely removed the lav P-trap and sealed it at the wall, removed the WC on the odd chance the wax seal had a leak, plugged the bath overflow and filled the tub with water. Nothing worked.

Basically, there were no plumbing openings left in the bathroom, but the odor continued. I just had the septic tank company come over and do a smoke test (fan powered) on the odd chance that a vent fitting had not been glued and was coming loose, but absolutely no smoke was seen in the house, attic or crawl space. I also put a hose down the 3" vent serving the problem bathroom, and also saw no evidence of water in the attic, walls or crawl space

There is no odor in the attic space or the conditioned crawl space, or outside the house. Another head scratcher is that there is another bathroom on the ease side of the problem BR, and another bathroom on the east side of the problem bathroom. These also have absolutely no odors.

Also, there is no furnace to blow an odor from somewhere else (hot water heating), and water heater is tankless, so there is no floor drain in mech room. No AC so no condensate drain scabbing into plumbing vents.

I have even taped over the bathroom exhaust fan as I grasp at straws. There is no opening into either room that plumbers or I can find to let any gas into the rooms.

Does anybody have a crystal ball or even a wild arse guess as to what other possibilities might be causing this?

Thanks!

 

[RickEG]

I come from a plumbing family and have had countless experiences with sewer odor occuping or should i say invading their homes or restaurants. Just last week I came accross a simuliar situation. The solution to that was the vent was to low and was being sucked in at the AC unit located up on the roof. Also are your sewer waste lines cast iron? If so the lead filled joints? Exhaust fan duct? Properly vented? Ducts in attic not damaged ripped?torn?chewed through by critters. Being drawn in by bath exhaust? Believe it or not all those have come into play. I Would love to hear some good news if not I will give a B-side to your problem. Good luck!

Hi All,

There is a sewer gas odor that seems to come from nowhere. The problem started 2 years ago right after we bought the house. Previous owner said he had no problem and I believe him (there was no odor the 3 times we looked at the house prior to buying, and nobody would live with that for the 5 years they owned it).

The septic tank was pumped just prior to us moving in, so I suspect it has something to do with that, but I do not know what. House is only 7 years old, one story with 4 1/2 bathrooms. The odor is only in one BR and the attached bath. The bedroom at times seems worse than the bathroom.
The main waste drain to the tank exits the house under the problem bathroom, but the lawn outside shows absolutely no evidence of a septic tank leak

To save everyone a lot of typing, I regularly add water to all the bathroom fixtures that we don't use (kids are grown so we only use 1 1/2 bathrooms). With this ongoing problem, I got so frustrated that I completely removed the lav P-trap and sealed it at the wall, removed the WC on the odd chance the wax seal had a leak, plugged the bath overflow and filled the tub with water. Nothing worked.

Basically, there were no plumbing openings left in the bathroom, but the odor continued. I just had the septic tank company come over and do a smoke test (fan powered) on the odd chance that a vent fitting had not been glued and was coming loose, but absolutely no smoke was seen in the house, attic or crawl space. I also put a hose down the 3" vent serving the problem bathroom, and also saw no evidence of water in the attic, walls or crawl space

There is no odor in the attic space or the conditioned crawl space, or outside the house. Another head scratcher is that there is another bathroom on the ease side of the problem BR, and another bathroom on the east side of the problem bathroom. These also have absolutely no odors.

Also, there is no furnace to blow an odor from somewhere else (hot water heating), and water heater is tankless, so there is no floor drain in mech room. No AC so no condensate drain scabbing into plumbing vents.

I have even taped over the bathroom exhaust fan as I grasp at straws. There is no opening into either room that plumbers or I can find to let any gas into the rooms.

Does anybody have a crystal ball or even a wild arse guess as to what other possibilities might be causing this?

Thanks!

 

[WR Don]

I come from a plumbing family and have had countless experiences with sewer odor occuping or should i say invading their homes or restaurants. Just last week I came accross a simuliar situation. The solution to that was the vent was to low and was being sucked in at the AC unit located up on the roof. Also are your sewer waste lines cast iron? If so the lead filled joints? Exhaust fan duct? Properly vented? Ducts in attic not damaged ripped?torn?chewed through by critters. Being drawn in by bath exhaust? Believe it or not all those have come into play. I Would love to hear some good news if not I will give a B-side to your problem. Good luck!

 

[WR Don]

Thanksfor the ideas, RickEG.

Pies are all ABS, though, and there is no AC. I had covered the exhaust fan opening with visquine and duct tape. The pipes and the duct have s have been checked in the attic, and all are intact. The smoke test showed no leaks in the crawls space, house or attic, so it is really a head scratcher.

As of last weekend, the odoir has begun to abate. Not sure if this is just one of those times where it intermittently disappears or it will continue (although nothing has changed. We shall see...