Chemical Disinfectants

Chlorination

The use of chlorine and its compounds is a very common disinfection method. This is not a popular home treatment method but is usually employed for large-scale treatment of water by the municipal supply.

Chlorine is known to be effective against bacteria but has its limitations. Most importantly, it fails to protect against the nasty Crypto and is rather unreliable against Giardia. High chlorine concentrations have objectionable odor, and it reacts with some organic compounds to form a strong unpleasant taste. Trihalomethanes, by-products produced when chlorine reacts with humic and fulvic organic compounds present in natural water may have potential adverse health effects. Despite these drawbacks chlorination is widely used for the large-scale disinfection of water, as the advantages are more than its ill effects.

Bromine and Iodine

This disinfection method involves adding bromine or iodine to water to destroy unwanted organic species. It has been proven effective in controlling most disease producing bacteria, even with relatively short contact time. These methods have been used successfully for disinfection of swimming pools, but bromine is not recommended for drinking water. Iodine disinfection is only acceptable for short-term emergency use, but not for long-term routine drinking water supply application. Iodine’s effectiveness drops dramatically as water becomes colder, if it contains decomposed materials or has a low pH. In addition chemicals add an unpleasant smell and taste to water and they have been shown to contribute to liver damage after prolonged use.