Chloramine

Category: disinfectant

Written by WaterFilterMatch Editorial TeamApril 2026

EPA MCL

4 mg/L

Status

EPA Regulated

NSF Standard

NSF/ANSI 42

Health Effects

Eye and nose irritation, stomach discomfort, and anemia at levels above the MRDL. Toxic to fish and aquatic life - aquarium owners must treat chloraminated water. Harder to remove than free chlorine.

Source: EPA National Primary Drinking Water Regulations

Where It Comes From

Formed by combining chlorine with ammonia. Used as a secondary disinfectant because it is more stable than free chlorine and maintains residual throughout the distribution system with fewer disinfection byproducts.

Where It's Commonly Found

Used by approximately 20–30% of U.S. water systems, including many large utilities (Washington D.C., San Francisco, Denver, Portland). Growing in adoption as utilities seek to reduce DBP formation.

Intentionally present in 20–30% of U.S. public water systems. Regulated as a Maximum Residual Disinfectant Level (MRDL). The MRDL of 4.0 mg/L is rarely exceeded.