u/ButtSucker_

So I have a pretty bad drain fly issue but can't seem to figure out where they're coming from exactly. They started in my master bathroom then migrated through the kitchen and then the guest bathroom blew up with them. I decided to see if I could isolate and block a few things off in the guest bathroom to see if I could stop them from popping up in there. It was by no means an attempt to get rid of them, just a way to try and narrow down where they're coming from in that room specifically. So I plugged the vanity drain and filled the sink with water to stop them from coming through there, then I completely tapped off the bathtub drain and overflow. I also put dawn dish soap in the toilet and sloshed it around just in case they're coming up through that. However even with all of that, they're still popping up in that room. Where could these be coming from at this point?