Sewage pollution has great impacts on water and sediment quality of an aquatic body which ultimately affects the all lives of the ecosystem. It is one of the major problems in cities. The sewage water is rained off into rivers without treatment. The careless disposal of sewage water leads to a chain of problems, such as spreading of diseases, eutrophication, increase in Biological Oxygen Demand (BOD), etc. The sewage contains water as the main component, while other constituents include organic wastes and chemicals.The present work is based on a case study carried out at the Rajakhali canal connected to main channel of the Karanfully river. The book contains sources,composition and effects of sewage on the Karnafuli river. It also includes the treatment procedure of the sewage.The books will be useful for the department of environment, urban planning, environmental managers, graduate students and researchers on this line.