Why Does My Upstairs Smell Like Sewage?

Why Does My Upstairs Smell Like Sewage? Possible Causes for the Sewer Smell: leaks from rotted or cracked drain pipes. a clogged drain. loose-fitting pipe connections. a stopped-up or too-short vent pipe. How do you get rid of sewer smell in bathroom? The trusty non-toxic combo of baking soda and vinegar can clean drains naturally.