In the current scenario, the availability of safe and clean drinking water is decreasing day by day. To overcome this difficulty, Nanotechnology has been undertaken to explore various efficient ways for treatment of waste water in a more precise and accurate way with the support of various nanomaterials. Nanoparticles (NPs) have huge potential that enables them to participate in waste water treatment and/or water purification technologies. Their exclusive features such as high surface area, high mechanical properties, greater chemical reactivity, lower cost and energy, allow them to eliminate precisely toxic metal ions, viruses, bacteria, organic and inorganic solutes from the waste water. Different types of nanomaterials such as metal nanoparticles, nanosorbents, bioactive nanoparticles, nanofiltration (NF) membranes; carbon nano tubes (CNTs), zeolites and clay are proved to be efficient materials for waste water treatment. This review discusses recent developments in various nanomaterials used for waste water treatment and/or water purification technologies such as adsorption, catalysis and disinfection. Special attention has been given to three major classes such as organic, inorganic and biological water pollutants. In addition, promises, facts and challenges of these new technologies have been seriously examined. © 2017 Bentham Science Publishers.