Practical applicability of water is playing a major role in each and everyday of human lives. Water for use may be pure or impure depending on the practical applicability of their usage. Taking a simple example of washing the floor can be an impure form, but when it deals with the consumption of human being or cattles the water must meet the standard sets given by the International and National Governmental Environmental Agencies. This is a phase for direct contact with the person, but for industrial purposes the quality of water must be very high. But strictly saying the quality of water directly depends on the usage specific or production specific functionalities. The quality of water required in the, Tanning industry may not be the same in the Electroplating Industry. There is one more recent development, which is compelling the industries to go for wastewater treatment, which is a zero liquid discharge of the industrial wastewater from the municipal sewer. But coming to specific treatment processes, Chemical treatment, is the one which is extensively used in the field of treatment of water in both domestic as well as industrial purposes.The usage of alum and chlorine in the field of water treatment can be done extensively in domestic as well as industrial purposes. . Hence in this paper, subsequent to this series, the authors have come across many chemicals used in the field of water and wastewater treatments.