Chlorine (Disinfectant) in Drinking Water

Overview

Chlorine is the most widely used drinking water disinfectant in the United States. While essential for public health, it can react with naturally occurring organic matter in water to form disinfection byproducts (DBPs) such as trihalomethanes and haloacetic acids. The EPA regulates both chlorine levels and DBP levels separately. The EPA Safe Drinking Water program sets and enforces the maximum contaminant levels shown here.

Health Effects

At levels above the MCL, chlorine can cause eye and nose irritation, stomach discomfort, and may increase the risk of bladder cancer through disinfection byproducts (THMs and HAAs) formed when chlorine reacts with organic matter. Most health concerns relate to byproducts rather than chlorine itself.

Sources of Contamination

Chlorine is intentionally added to drinking water as a disinfectant to kill bacteria, viruses, and other pathogens. It has been used in water treatment since the early 1900s and is responsible for virtually eliminating waterborne diseases like cholera and typhoid in the US. Over-chlorination can occur due to equipment malfunction or during emergency disinfection.

Treatment & Removal

Activated carbon filters (including basic pitcher filters and faucet-mount filters) effectively remove chlorine from drinking water. Letting water sit uncovered for 24 hours will also allow chlorine to dissipate. Whole-house carbon filters can remove chlorine at the point of entry.

How to Remove Chlorine (Disinfectant) From Water

These filtration methods are effective for reducing Chlorine (Disinfectant) in drinking water:

Water Systems with Chlorine (Disinfectant) Detected