With the unit removed you can see a hole is cut in the berth.
Starting at the bottom is a hole cut in the hull with a short fiberglass tube formed around the hole. A piece of hose over the tube, then the float valve (the loose piece pictured), then another piece of hose leading to the sink drain tail piece.
This arrangement could all be improved.
The cruddy green garden hose led from the water tank to the sink drain pump.