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 Ongoing sewage smell in brand new home
Author: Allister108 (IN)

Hello everyone.

I came across this forum during a Google search (something I spend a great deal of time doing these days) and it appears there are some very knowledgeable people hanging out here. I desperately need some guidance, and if anyone can offer any help, I will be extremely grateful.

I moved into my new custom home in January of this year. In early April, we first noticed the smell of sewage. This smell comes and goes - sometimes it's completely absent and other times it's unbearable to be in the home. A little background: it's a 3600 sq ft 2 story home with a finished basement. It's multigenerational, meaning that I live on the main and upper floor with my family, and my retired parents occupy the basement "condo" with a separate entry. Our lot is just over an acre, with a large septic system to accommodate 2 kitchens, 2 laundry rooms, 4 full and 2 half baths.

Over the past several months, our builder and his plumber have tried various tests to try to determine the origin of the smell. We are all pretty certain that it originates in the basement kitchen. A few weeks ago, the plumber finally did a smoke test (the plumber didn't previously own the machine and wanted to test other options before making the investment). I fully expected we would get the answers we had been looking for for months, but the test was inconclusive.

Since then there have been a few other tests done, but it really seems like our builder is grasping at straws at this point. He's made it very clear that he nor his plumber can figure out what's going on. After doing some research today, I have some concerns about the smoke test that was done. It seems that they are typically done by blowing smoke into the cleanout, which I learned today our septic system doesn't even have. They blew the smoke in from the roof vent, and so much smoke was billowing off the house, the plumber commented that someone might call the fire department. However- they did open the drain vent under the basement kitchen sink during the test, and smoke came out. So some smoke reached the basement pipes. But was there enough to potentially fill a wall cavity and push out a light switch, outlet, etc?

Really I just want to speak with anyone with experience in this area. Our builder feels terrible, and is by no means trying to blow us off, he just has never dealt with anything like this in 30 years of building.

Any input would be so greatly appreciated. We are absolutely desperate for help.

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 Re: Ongoing sewage smell in brand new home
Author: srloren (CA)

Sometimes an odor you describe comes out of a floor drain in the laundry because the trap is dry. Have you checked this possibility. Just make sure there is water in all of the traps to create a seal preventing sewer gas from entering the structure.

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 Re: Ongoing sewage smell in brand new home
Author: Allister108 (IN)

Thanks for replying! We did make sure none of the drains were dry. When I first smelled the odor in April, I suspected that the basement floor drain might be the culprit. We spent a couple weeks doing trial and error, pouring water into all the drains, flushing unused toilets, etc. Our builder also sealed our ejector pit during that time frame.

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 Re: Ongoing sewage smell in brand new home
Author: packy (MA)

contact a company that does 'blower door tests'.
ask them if it is possible to do one on an occupied home.
this test should pull the smell for where ever it is coming from.
[www.google.com]

by the way. septic systems are sized according to how many bedrooms you have.

more bathrooms don't mean more people but more bedrooms mean more people.
more people equates to more plumbing being used.

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 Re: Ongoing sewage smell in brand new home
Author: Allister108 (IN)

Thanks for the info! I found a local company that does blower door tests. They are closed now, but I'll give them a call tomorrow and ask some questions.

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 Re: Ongoing sewage smell in brand new home
Author: sum (FL)

Any chance it's not the smell of sewage but something else that's rotted or decaying?

I would try and document when, where you detect that odor on a calendar and see if there is some sort of a pattern. Does it happen when you come home after work when the house has been unoccupied for hours, or does it happen after a specific fixture was used? Is it totally intermittent, or seems to follow a certain time interval? Does it happen when the air conditioner is on or off etc etc etc...

May be there is something about not smelling it from January to April? Why? Was that when rain season started? When it's warm up to use the air conditioners?

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 Re: Ongoing sewage smell in brand new home
Author: Palm329 (VA)

Can’t high winds over the roof vent pipes cause this also? I forget what it’s called. Venturi effect or something like that?

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 Re: Ongoing sewage smell in brand new home
Author: bernabeu (SC)

? Failed AAV ?

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 Re: Ongoing sewage smell in brand new home
Author: Curly (CA)

On occasion you can get sewer smells back in a building/house from the sewer vent pipes on the roof thru ac units and or exhaust fans.

Sometimes this happens with no rhyme or reason.

On commercial buildings some times just extending the vent pipes above the parapet will solve the problems. Gets the pipe(s) out of the air path to ac units and or bathroom exhaust fans etc.

If this does not work you can install vent pipe filters that contain charcoal.

Try searching for odor hog vent filters.

On residential buildings sometimes it is not as easy to extend the vent pipes so you might just try the filters.

This problem is either real easy to solve - eg. dry trap or very difficult...........

Just my 2 cents.

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 Re: Ongoing sewage smell in brand new home
Author: claytonclive (FL)

It could be due to a dried-out water seal in a floor drain. Other times a sewer gas smell is a sign of a bigger problem, such as a broken sewer or vent stack. Diagnosing this problem can be simple or complicated, depending on the cause of the problem. Likely there is a blocked, broken, cracked or deteriorated pipe allowing the gas to enter your home. It’s not going to go away until it's repaired.

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 Re: Ongoing sewage smell in brand new home
Author: packy (MA)

I have seen a new house (modular home) that had a long screw used to mount a kitchen cabinet driven thru a PVC stack.
no smell but a leak dripped off the bottom of the stack in the basement when the upstairs bathroom was used.
the walls in that vicinity looked like swiss cheese before I eventually found the problem.
the cost of the actual repair was minimal but the cost of locating, accessing and subsequent repair was a couple thousand.

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 Re: Ongoing sewage smell in brand new home
Author: mbilsky (OH)

I have had an eerily, similar experience (new build, builder and plumber have tried everything and are stumped), hence me turning to google. Did you ever find the source of the smell/ resolve the issue?

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 Re: Ongoing sewage smell in brand new home
Author: Ralph36 (MD)

I have had a somewhat similar issue myself. The smell started in my first floor bathroom and then it has migrated to other bathrooms. All the plumbing at this point has been checked out, yet it seems to be coming up from the pipes, but maybe it's the water itself? We are going to look into getting the water tested to see if there is something present in the water that is causing it to smell.

Instead of a smoke test, we tried a peppermint test. That showed us that a studer vent under the sink needed to be replaced, but nothing else. We have not put a camera to look at the sewer line out by the street, but the smell is not actually a sewer smell, so that doesn't seem very likely. All the plumbers have said that it doesn't have a typical sewer smell.

So we are still trying to find a solution. The blower test sounds interesting, but I'm not sure why that would give better results than a peppermint or smoke test.

Definitely baffled and losing my mind and money trying to figure this out. Appreciate any advice.

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