Chloramines (also known as secondary disinfection) are disinfectants used to treat drinking water and they:

• Are most commonly formed when ammonia is added to chlorine to treat drinking water.
• Provide longer-lasting disinfection as the water moves through pipes to consumers.

Chloramines have been used by water utilities since the 1930s.  More than one in five Americans uses drinking water treated with chloramines.

Water that contains chloramines and meets EPA regulatory standards is safe to use for:

• Drinking
• Cooking
• Bathing
• Other household uses

Many public water systems (PWSs) use chlorine as their primary disinfectant. However, some PWSs changed their secondary disinfectant to chloramines to meet disinfection byproduct requirements. Since then, consumers have raised questions about this switch in disinfection.

EPA scientists and experts have answered these frequently asked questions about chloramines

The question and answer format takes a step-wise approach to communicate complex information. Each question is answered by three key responses written at an approximately 6th grade reading level. In turn, each key response is supported by three more detailed pieces of information written at an approximately 12th grade reading level.

• Basic Information about Chloramines and Drinking Water Disinfection
• PWSs, Disinfection Byproducts, and the Use of Monochloramine
• Chloramines-Related Research

EPA continues to research drinking water disinfectants. EPA expects to periodically evaluate and possibly update the chloramines questions and answers when new information becomes available.

More information about health effects and drinking water disinfection from EPA is available in the following locations:

• EPA’s Integrated Risk Information System (IRIS) website
  IRIS includes updated information up to 2005 for the oral and carcinogenicity assessments for chloramine. The assessment is found under heading monochloramine.
• Drinking Water Health Criteria Document for Chloramines This document provides the health effects basis to be considered in establishing the maximum contaminant level goal for chloramines.

Back to the Stage 1 & Stage 2 Disinfectants And Disinfection Byproducts Rules page.

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