[Abstract>: The city-waste water is let progressively at random. We should build the waste water treatment plant full-scale and we should use automation system in it. This paper introduces The application and network of The Schneider Electric PLC in the waste water treatment plant . The use of PLC system makes the equipment running in a steady and rationalization state. It prolongs the equipments’ lives and it economize the energy sources. [Key Words>: waste water treatment, Premium PLC ,Orbal technic , worknet ,VB6.0 ,report forms ,energy sources