Nanotechnology is one of the most advanced and progressive topics in interdisciplinary research. It has a huge application in many branches of science and engineering such as medicine, biotechnology, consumer goods, construction, environmental etc. Above all these it has wider application in the environmental engineering such as waste water treatment. Having the unique properties like greater surface area, able to work at low concentration, nanomaterials have a supreme potential to improve water quality. Nano adsorbents, nano filters, nanomembranes, disinfectants, nano catalysts have been frequently utilized for water purification. Many researches are going on in the field of nanotechnology for solving the problem of polluted water in more precise and accurate way though many challenges and issues are present in waste water treatment. The main focus of this book is to describes the applications for the removal of various types of impurities from polluted water (containing organicand inorganic impurities) through Nanotechnology.