What You Need to Know About Disinfection Byproducts in Drinking Water
Drinking water drawn from surface water sources, such as Lake Champlain, must be disinfected to kill bacteria, viruses and other organisms that can cause serious sickness and death.
The Environmental Protection Agency (EPA) requires that public water systems use chlorine at specified levels for “primary” disinfection at the water treatment facility. “Secondary” disinfection is also required to treat any type of contamination that could happen after the water leaves the treatment plant. The EPA approves three disinfectants for use as a secondary disinfectant: chlorine, chlorine dioxide and monochloramine.
Monochloramine is a chemical that is made by combining chlorine with ammonia. Although it is a weaker disinfectant than chlorine, monochloramine is more stable, remains effective in the water system over longer distances for a longer period of time, and forms lower levels of regulated disinfection byproducts than chlorine.
Monochloramine has been used in the U.S. as a secondary disinfectant since the 1930s. While the EPA does not know the absolute number of people who are using water treated with monochloramine, it is estimated that the number exceeds the 68 million who were identified in a 1998 survey. In New England, more than 3 million people in 135 communities are served by monochloraminated water.