My bsmt bathroom smells bad!
Just moved to a new house and notice that my basement bathroom stinks. I’ve taken shower there few times and turned on all the water to flush anything out, however the smell goes away briefly and come back in question of minutes.
I just noticed that their is a branched pipe comungo from the sink to the shower drain and I believe that is the issue. Since it’s above the shower trap, I believe it gets dry easily since it’s a 1” pipe and when the water comes from the sink isn’t much.
How can I solve this smell issue? Do I need to redo the plumbing?
Tried a few ways to unclog it, wash, being some nice smell but it doesn’t work. I believe there is biofilm or any dirty from the sink through the branch pipe that can’t mostly be cleaned.