The sump system is underneath. I plumed in a new water line and drainage, along with air flow coming from under the house. It is accessible only from the front because couldn't find a clean enough way to make it accessible from the back side. The sad part, is there is an awesome view of the tank from within the coat closet.....but nobody cares to stand in there to get the awesome view (I made the closet view so that I can clean the glass on all sides).