In this book,Sewage is waste water carrying wastes removed from residences, institutions, commercial and industrial establishments, together with such groundwater, surface water, and storm water as may be present. Its chemical constituents and the bacteriological organisms that it contains. So there is great need to treat waste water. We can treat such water by various methods. The contaminants in waste water are removed by physical, chemical, and biological means. We can achieve desire results with the help of PLC. Using PLC we want to develop an automated continuous process system for treating the waste water. In this book we are discussing how we are going to develop this system, what the basic theme of this system is and how our ideas will be applicable to the theme. We have designed a control system particularly a batch process. The purpose of the book is to alleviate the severe impacts of uncontrolled sewage discharges into the environment. Proper design, selection, construction and management of the waste water treatment plants and upgrading, construction of waste water collection networks would mitigate such negative impacts.