Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water. Water which has been treated with chlorine is effective in preventing the spread of diseases.
The chlorination of public drinking supplies was originally met with resistance, as people were concerned about the health effectsof the practice. The use of chlorine has greatly reduced the prevalence of waterborne disease as it is effective against almost all bacteria and viruses
Chlorination is also used to sterilise the water in swimming pools and as a disinfection stage in sewage treatment. It can also apply to the addition of chlorine to other elements, such as gold in the formation of gold chloride.
The Benefits of Chlorine
Current scientific data shows that the benefits of chlorinating our drinking water (less disease) are much greater than any health risks from THMs and other by-products. Although other disinfectants are available, chlorine remains the choice of water treatment experts. When used with modern water filtration methods, chlorine is effective against virtually all microorganisms. Chlorine is easy to apply and small amounts of the chemical remain in the water as it travels in the distribution system from the treatment plant to the consumer's tap,This level of effectiveness ensures that microorganisms cannot recontaminate the water after it leaves the treatment plant.
Alternatives to Chlorination
A number of cities use ozone to disinfect their water, because ozonation does not produce THMs. Although ozone is a very effective disinfectant, it breaks down quickly and cannot be used to maintain disinfection in the distribution system. Small amounts of chlorine or other disinfectants still must be added. Renovating water treatment plants so they can use ozone can be expensive.
Examples of other disinfectants include chloramines and chlorine dioxide. Chloramines are weaker disinfectants than chlorine, but are very effective in the distribution system. Chlorine dioxide can be used in the treatment plant, but it is not very effective in the distribution system .
All chemical disinfectants used in drinking water can be expected to form by-products that could affect human health. In general, we know less about the by-products of other disinfectants than about chlorination by-products.
What Impurities Will Chlorination Remove?
Chlorination is a water treatment that destroys disease-causing bacteria, nuisance bacteria, parasites and other organisms. Chlorination also oxidizes iron, manganese and hydrogen sulfide so they can be filtered out.
Disease-causing bacteria can infect humans and animals in several ways. Fecal waste from an infected host frequently carries organisms which cause diseases such as typhoid fever, paratyphoid fever, bacillary dysentery, infectious hepatitis and others. Disease-causing organisms are transmitted from host to host in many ways including through a contaminated water supply. Human and/or livestock populations concentrated together with improperly located or constructed wells may result in contamination of water supplies by sewage or fecal wastes.
There is no substitute for a safe and sanitary water supply. If your water supply becomes contaminated, elimination of the source of contamination is the most permanent solution. Continuous chlorination to kill disease-causing bacteria in a contaminated water source should be a temporary measure used only until you can develop a new, sanitary water supply.