a floor drain is almost essential. but they also have to be desinged so that it can effectivley drain large amounts of water through. I have never thought of an over head water system but it could work. I had a stock sink and a watering hose which I use to do water changes and fill tanks (I have my own well so my water goes directly into the tanks. I think is is best to have a sump system if you have multiple coomunity aqariums, it makes for easy filling and filteration of the tanks. If you have any more questions I can tell you what I did in my fish room, and what I have seen.