The disinfection of potable water is almost universally accomplished by the use of chlorine compounds and several chlorine-related compounds for water disinfection can be found. The primary objectives of chlorination process are disinfection, taste and odour control in the system, preventing the growth of algae and other micro organisms that might interfere with coagulation and flocculation, keeping filter media free of slime growths and mud balls and preventing possible built up of anaerobic bacteria in the filter media, destroying hydrogen sulphide and controlling sulphurous taste and odour in finished water, removing iron and manganese, bleaching of organic colour.