In our large unfinished basement a sewage smell that appeared for about the past 4-6 weeks. It localizes to the area immediately underneath the drain for the 1st floor toilet, although the drain pipe from the 2nd floor bathroom is only 12 inches away. There is mild staining of the otherwise dry, non-rotted subfloor from below around both drains, and the house is 24 years old.

I replaced the wax rings for both toilets, cleaning up much gunk on the floor as well. We thought the smell went away for a week, though were just probably being optimistic.

Could this be a venting problem? The bathrooms on the 1st and 2nd floor where the toilets reside do not have this smell. Any ideas appreciated.

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Originally Posted by bgott

In our large unfinished basement a sewage smell that appeared for about the past 4-6 weeks. It localizes to the area immediately underneath the drain for the 1st floor toilet, although the drain pipe from the 2nd floor bathroom is only 12 inches away. There is mild staining of the otherwise dry, non-rotted subfloor from below around both drains, and the house is 24 years old.

I replaced the wax rings for both toilets, cleaning up much gunk on the floor as well. We thought the smell went away for a week, though were just probably being optimistic.

Could this be a venting problem? The bathrooms on the 1st and 2nd floor where the toilets reside do not have this smell. Any ideas appreciated.

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When you cleaned up the gunk did you disinfect the area with bleach before you reset the toilet? If the floor and sub floor is dry then I would suppect the sewer smell has permeated the wood and that's what's giving off the odor. If your basement has a floor drain that hasn't been used for some time I would suppect that also. If your vent was blocked I would be hearing complaints about the fixtures on the first and second floors gurgling every time you flushed or drained the tub. Good luck, Tom