Bubbles, This is what I have seen: a steel plate over the pit with maybe a half inch gap around the edges to drain washdown water (this is not a trench pit). This wash has a chain link fence to divide the bay into two and the 1 1/2 inch drain line from the tubs follows the fence into the pit. From what I saw, this setup works fairly well and is lots cheaper and easier than digging in concrete to bury the drain. As for input, if your washes are two or more bays over from the equipment room, then you should consider recirculating your hot water out to the bay. Customers and their pets cannot stand waiting on the warm water. Hope this helps, and I am sure there are better ideas out there. Mitch