Chloramine is a disinfectant added to water for public health protection. It is a combination of chlorine and ammonia that is currently considered best technology for controlling the formation of certain regulated organic disinfection byproducts.
Chloramine was used as a disinfectant in the entire distribution system in the Bay Area for ten years between 1935 and 1944 when the Hetch Hetchy water supply was first brought to the San Francisco Peninsula from the Sierra Nevada Mountains. Many utilities used chloramination at that time, including 34 other drinking water supplies in California in the 1930s. Chloramination was discontinued in 1944 at SFPUC and many other utilities due to shortages of ammonia during World War II. We started using chloramine as a distribution system disinfectant again in February 2004 to better comply with the new federal drinking water regulations, which require more stringent control of chlorination by-products. There is a significant amount of on-going research by many agencies worldwide regarding best disinfection practices for control of microorganisms in drinking water and simultaneous minimization of chemical disinfection by-products. We continually monitor that research and the latest information on water disinfection practices.
Since 2004, chloramine has been very effective as a distribution system disinfectant in San Francisco’s distribution system. It has lowered microbial densities (including coliform bacteria, heterotrophic bacteria, Legionella bacteria), at the same time minimizing the formation of regulated disinfection by-products.
Chloraminated water is safe for people and animals to drink, and for all other general uses (for support, see a consensus statement from the California Conference of Local Health Officers plus a medical opinion from Tufts University School of Medicine. However, as with chlorine, chloramine will need to be removed for fish and amphibian use, and for people or businesses requiring highly treated water.
There has been some confusion amongst certain groups as to what form of chloramine is present in our water. A recognized chemistry expert outlines his opinion that, because of our corrosion control method, only monochloramine, the least reactive form of chloramine, is formed in our drinking water. READ - Opinion as to Probable Chloramine Speciation in SF Public Utilities Drinking Water Distribution System. For additional information please read Questions and Answers Regarding Chloramine (referenced, peer-reviewed).