Smelly shower drain
I work as a PM in an old quadruplex with a raised foundation. One of the tenants in a bottom unit began to complain of a smelly shower drain.
I went over to check it out and sure enough, it smelled rotten. The smell got worse when I turned on the water and then went away quickly; I assume because the water in the drain displaced whatever gases were forming in the pipe.
The sink and toilet do not smell.
I had the drain rooted, and the smell came back after about a week. I then came back and scrubbed what I could reach in the pipe myself; I also used boiling water and enzymatic cleaner from Green Golbbler to eliminate any biofilm that was further down.
Again the smell went away for a week or two then returned.
I'm having the same plumbing company come back out to check for a cracked pipe, but want to ask if anyone here has any ideas about what might be causing the issue. And also if there's anything I need to be sure to ask the plumber to check.