I can't tell how strong the odor and where it came from.

The odor was incredible. 

I can understand the concern because of the odor, but your question did not include smoking marijuana or taking marijuana pills for medicinal purposes. 

As soon as I and renewed the lease the tenant wrote me this long message with all these things wronge, including drain smells bad(she’s been putting bleach down the drain to kill the odor, the lights in the kitchen and bedroom are flickering(this ones easily fixable) & the bathroom floor is in-caving because of water damage(she suggested a new shower door).

Was the odor seeping through shared vents or through firewall or what?

.- Read biography on Theodore Roosevelt

Theodore Roosevelt 1907

The odor you probably smell is sulfer and other minerals in the water.

Theodore Rivera Hey Ted, welcome to Bigger Pockets!

We have steam cleaned the carpet several times, but the odor remains.