I have had a relaxa mist steam unit installed in a new shower and before I go ahead and finish the shower I want to make sure everything is correctly installed. I noticed that the drain is not attached to anything. The installation manual lists it as an optional drain feature but from my understanding you need to flush the system every so often. Does anyone know how this works? I have gone to their web site and read through the manuals but I can't find anything. Thanks! Sheila.