Chloramine

What is Chloramine?

Chloramine is a disinfectant made by combining chlorine with a small amount of ammonia. About one in five U.S. water systems uses it instead of plain chlorine because it lasts longer in the pipes and forms fewer regulated disinfection byproducts. Utilities that switch usually notify customers, because the change matters for two groups: people on kidney dialysis, whose equipment must remove it, and aquarium owners, since it is toxic to fish.

At the EPA maximum residual disinfectant level of 4 mg/L, chloramine is not considered a health risk for drinking, bathing or cooking. It is less reactive than free chlorine, so the water tends to taste and smell milder. The trade-off is that it forms its own, less studied byproducts — nitrosamines such as NDMA among them — which the EPA lists as candidates for future regulation.

Chloramine is also harder to remove than chlorine. A standard carbon filter takes it out only slowly; catalytic carbon or a longer contact time is needed, and filters that claim chloramine reduction are certified under NSF/ANSI 42 for that specific claim. Boiling and letting water sit do not remove it.

Commonly found in: Municipal tap water, Well water, Water filter claims, Lab-tested products

Sources: Chloramines in Drinking Water · Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules