I went down teh normal route of trying to use a humidity sensor. I tried Aeon and I tried Smartsense and what I discovered is they take forever to register the change and by that time the bathroom is already fogged up. then it hit me. The flood sensor the sell at lowes (Utilitech) could be used to triger the event since it reports in under a minute with the native Smartthings Device Handler. A little Silicone sealer a drill (1/64 drill bit) and some good JB Weld to make sure it stays in place and you end up with this on your drain. Works like a charm. Set it at a slight up facing angle with one probe slightly above the other so the water will flow off of it so it will reset being wet.
