Chloramines are produced at the water plant by combining ammonia with chlorine. There are three inorganic chloramines in water: monochloramine, dichloramine and trichloramine. Monochloramine is stable in drinking water with a pH level of between 7 and 9. As chlorine concentration increases and pH is reduced, dichloramine and trichloramine will form. Dichloramine and trichloramine formation is especially problematic, because they are very irritating and even less effective disinfectants than monochloramine. Organic chloramines are produced by the same chemistry as inorganic chloramines used in water disinfection.
Drinking water is disinfected with chlorine and/or chloramine to protect public health. Prior to widespread disinfectant use, many people became ill and even died because of water contamination. Disinfection reduces sicknesses acquired through drinking water. The Environmental Protection Agency (EPA) and the Centers for Disease Control (CDC) believe the benefits of drinking water disinfection outweigh the potential risks from disinfection byproducts (DBPs). Chemical disinfection inactivates bacteria, viruses and other harmful organisms, preventing infectious diseases like typhoid fever, hepatitis, and cholera.
For this reason, water utilities have been using chloramines for more than 90 years. According to the EPA, research and general experience indicates that monochloramine use at regulated levels is a reasonably safe means for disinfecting drinking water. After primary disinfection (e.g. free chlorine), chloramines are typically used to help inhibit regrowth of bacteria and formation of disinfection byproducts (DBPs) while water is being distributed to consumers. Chloramine is reported to produce fewer DBPs than chlorine, but some of them may be more troubling than those produced by chlorine. For example, chloramine will react with dimethylamine in water to produce NDMA (dimethylnitrosamine), a potent carcinogen. On the one hand, the EPA points to studies indicating that monochloramine produces lower levels of regulated disinfection byproducts compared to chlorine. On the other hand, the EPA also reports that water treated with monochloramine may contain higher concentrations of unregulated disinfection byproducts.
Monochloramine is the most effective disinfectant of the chloramines, but it reacts slower than chlorine. Chloramines remain active in water longer than chlorine. Chloramines are commonly used in chlorinated swimming pool water. The odor and eye irritation you experience in pools is not typically the chlorine, but instead is usually attributed to trichloramine in the water.
Public water systems are required to regulate the amount of chloramines they use when treating water. The maximum contaminant level (MCL) is 4 milligrams per liter (mg/L) or 4 parts per million (ppm), which is well above the typical use level. See your local water quality report for more information.
How can chloramines impact my health?
Hospitals and kidney dialysis centers must be alerted when chloramine is used for water supply disinfection. Cases of chloramine-induced hemolytic anemia in patients have been reported when their dialysis water was not appropriately treated. Persons with liver or kidney disease and those with hereditary urea cycle disorders may be at increased risk for ammonia toxicity from the consumption of chloraminated water.
Citizen advocacy groups raise concerns that chloraminated water vapor from showers, baths, hot tubs, dishwashers, and other household appliances contains volatile chemicals. When inhaled, they can cause irritation to the respiratory tract. Prolonged chloramine exposure may potentially damage mucous membranes, making the lungs more susceptible to allergens and infections. Some individuals have reported cases of skin reactions ranging in severity from rashes, itching, chapping, cracking, flaking to blistering skin conditions. Chloramine has been further known to aggravate skin conditions such as eczema and psoriasis.
Chloramines, like chlorine, are toxic to fish and amphibians at levels used for human drinking water.
A granular activated carbon filter has been known to help reduce the amount of chloramines in drinking water. Filters specifically designed to reduce chloramine are also available.