It was suggested that I ground the water line where it meets the pressure tank. The water source is a well which is completely plastic pipe. The only metal in the water system is a pex manifold, pressure tank, and hot water heater. Why would you need to ground the pressure tank? Can you count on the water in the plastic tubing to make a connection to the well casings? One other point I might mention is that there are already 2 ground rods.