We are at a loss and could really use some ideas on what to do. We moved into this ~40 year old house just about 2 months ago. Over the last 3-5 days we have observed a strong, bad smell coming from our basement utility room. It smells like sewer. We have now had the gas company, water company, 2 plumbing technicians all evaluate and still no major answers. The gas company rules out a natural gas leak. The water company said there’s no issue with the sewer connection and the water pressure is good. They also took a water quality sample. The first plumber investigated the sump pump, connections and confirmed we filled all of the p-traps with water. We also tried pouring bleach down the floor drain. The second plumber we conducted a sewer scope and he didn’t find any cracks or issues from that. He also wasn’t 100% convinced it was a sewer smell. He agreed it smelled terrible but he brought up the possibility of a dead animal in the walls.
We have heard the next step is to conduct a plumber smoke test but also read this can likely be a let down as 90% of the venting is in the walls.
We have replaced a few faulty/makeshift caps as well.
We talked to the previous owner and they said they had never experienced this before.
We also find the timing somewhat interesting as we recently cut on the furnace for the first time since moving here over the weekend due to falling temps.
The smell is staying largely consistent and you can smell it most strongly in the utility room but it’s also seeping out into the broader basement and now top of stairs.
Lastly, to top it all off we are having a new baby in 2 days and worried if there could be any concerns from a health or safety perspective.
Any advice- please share. Thank you!!!