Nanotechnology is an emerging science that has shown potential applications in solving current problems involving water quality. Nanomaterials are highly reactive, have a large surface area compared to their mass and can easily capture other particles. Hence nanotechnology is also used as an environmental technology to protect the environment through pollution prevention treatment and clean up. Additionally,__ampersandsignnbsp; anotechnology-derived products can reduce both chemical and biological impurities in water treatment. This article summarizes in the area of nanomaterial synthesis and the origin of their reactivity at the nanoscale in environmental clean up like water purification. In addition, we discuss the limitations associated with the potential applications of nanomaterials for water purification.