I’m at a loss on how to troubleshoot and resolve the bad sewer smell coming from the basement bathroom.

I live in this semi-detached house was built circa 1920. I purchased it in 2004. By 2007 I requested proposals for a basement tenant bachelor suite construction. Mind you, the 4-pc bathroom was already there at the front (street-side) of the house. The laundry area was always at the rear (backyard facing) part of the basement. I had a kitchen sink and laundry team installed under the kitchen counter. The main stack that goes from the basement to beyond the roof is located near here too. Also, the water tank and furnace are located on the side of the joint wall. The contractor dug out a sump pump system to pump out any excess run off water from the newly built walkout entrance.

In October, the tenant started to report a bad smell from the bathroom. At first I thought it might be a dying rodent. But it wasn’t that because the smell kept coming back. I called pest control and they suggested baiting because they needed to know where they would exterminate. We saw no traces of rodents.

I then remembered that the toilet was a bit wobbly and at the recommendation of a big box hardware store (Home Depot), I had shimmed the toilet in August because I am unable to take a toilet off and reinstall it. I decided to caulk the base of the toilet to see if that would contain the scent. For a few days the tenant reported that the smell went away but then it came back.

I contacted a plumber to investigate. They smelled the sink, toilet, bathtub & overflow, exhaust fan and heat vents in the washroom to no avail. Also, they put the snake down the tub and found nothing to be blocked or clogged. They left acknowledging the scent but not knowing its source in the bathroom.

Disappointed, I decided to call the gas company (Enbridge) to report the bad smell. Upon arrival as per policy, they shut off the gas to the home and did their tests. But the technician vehemently identified the smell as sewer smell and not rotten eggs; the scent that is added to gas for identifying purposes. The technician mentioned that they often get called for this very issue. The recommendation: get a good plumber.

I called back the plumbing company to report that the initial plumber’s visit had not rectified the smell. They dispatched a plumber to do a camera scope. Upon arrival, we could not locate a main drain. Ceramic tiles have been installed in the bathroom and at rear of the basement where the kitchen and laundry are. Laminate wood flooring exists in the living sleeping quarters area. The plumber took the toilet off and inserted the camera scope. He found no blockage and said I was fortunate to have the ‘trap’ already removed or that would have cost me a lot of money to do. He was looking for a dried up trap and found none. He then instructed me to turn on the water tap from the basement kitchen area and go to the top floor of the house and flush the toilet. He maintained that there was one area where the camera passed by that he could not see a flow of water empty out from.

Plumber’s recommendation: 1) locate the main floor drain (pull up ceramic tile?!). Perhaps ask the adjoined homeowners where their main drain is located in their basement.
2) Open up the drywall/gypsum wall (?!) where the plumbing exists for the sink/shower/tub to determine if there are any cracks/breaks/leaks/pea traps unvented/etc.
This plumber replaced the waxgaswnorn (?) and reinstalled the toilet again insisting he would not be able to determine the origins of the bad smell without having access to exposed pipes & main drain.

The smell does not emit from the rear laundry/kitchen/main stack/sump pump/HVAC/entrance walk-up stairs area of the basement which are all adjacent to the backyard. Also, the smell from the basement bathroom which is at the front of the house manages to creep its way to the upper level at the front of the house at times.

I asked my neighbour (of the attached house) where the main floor drain in their home. he has two, one in the laundry room and one under the furnace. both are located at the rear of the home. This is what I roughly remembered where my drain would have been located prior to the basement bachelor suite reno nine years prior. At the front of our homes, I have one main water pipe cap thing but my neighbour has two. I don’t know why a contractor would’ve ‘covered’ up the main drain. But, the drain may still be there, it may be underneath some cabinets that were installed in the kitchen area. On that thought pattern, I pulled out the bottom kitchen pots and pan drawer. There on the back wall is a maybe 4″ X 4″ metal plate with screws (I have a picture). I believe this is likely the main stack area & or drain systems for the house.

The sump pump is a 1/3 hp 257 Liberty Pump (www.libertypumps.com). It is closely located at the joined wall at the rear of the home. Currently, there is a 3/4′ (approx) hose pipe going from HVAC to the sump pump. From what I understood how the system works, is to take the entrance drain ‘runoff’ water and it would get pumped up a corrugated hose pipe (2-3″) up and over, running between the upper floor joists out to the exterior wall (same wall as the main stack), and in fact connected to that stack to empty into the ‘main drain system’. I’m not certain of the viability or ethics behind the system design, I’m explaining how it is set up from what the contractor told me.

In any case, once the toilet was put back with a new wax ring/gasket, the smell stopped for three days and then returned. I still have the smell coming from the bathroom location. I still wonder about the toilet. I looked at it and sat on it, it’s no longer moving at all. I wonder about the wax ring/flange/gasket seal thing, should there be a larger one – one that is maybe longer/deeper/double height or something? I wonder if a camera scope can go down the tub drain or sink drain to discover any breaks/cracks/leaks? I wonder what other tests are viable in this situation?

The smell is constantly coming from the front of the house in that bathroom area, because you can close the bathroom door and the smell is largely located there. The stronger the scent gets then it starts to creep.

What does your company suggest on this type of problem?


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