Hello
Have 2 rental over 90 yrs old in pittsburgh
Both get sewer smells if no bleach is poured in basement floor drains every month or so
No signs of any plumbing or drain problems
No ventalitation in either leaky basement
Thanks
Charles

The sewer smells are from the traps evaporating and allowing gas to seep into the building. Not much you can do about the evaporation, just add water periodically. Bleach isn't always necessary but it does help cover the odor already in the air.