what is chlorination

Chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water to kill bacteria, viruses, and other microbes in water. Chlorine is a highly efficient disinfectant and is added to public water supplies to kill disease-causing pathogens such as bacteria, viruses, and protozoans that commonly grow in water supply reservoirs, on the walls of water mains, and in storage tanks. Chlorination is a chemical disinfection method that uses various types of chlorine or chlorine-containing substances for the oxidation and disinfection of what will be the potable water source. Chlorination is a very popular method of water disinfection that has been used for many years and has shown to be effective for killing bacteria and viruses, but not for some protozoan cysts. Chlorination is required for public water systems that use surface water, such as rivers, lakes, and streams, as their source, have treatment processes that expose the water to outside or open air, or serve 25 or more people. Chlorine is available as compressed elemental gas, sodium hypochlorite solution (NaOCl), or solid calcium hypochlorite (Ca(OCl)2).