EPA legal limit
4 ppm
Maximum Contaminant Level
EWG health guideline
No guideline
Science-based, stricter target
Health effects
At the levels found in tap water (typically 0.2–1.0 ppm), chlorine itself is not considered a significant health risk. The primary concern is that chlorine reacts with natural organic matter to form disinfection byproducts (TTHMs and HAA5) that do carry health risks. Chlorine can cause taste and odour complaints and may cause skin and eye irritation in sensitive individuals.
Where it comes from
Added intentionally at the water treatment plant. Residual chlorine is required by EPA to remain in water throughout the distribution system. Levels are monitored continuously.
How it's regulated
EPA sets an MCL of 4 ppm for chlorine residual and an MRDL (Maximum Residual Disinfectant Level) of 4 ppm. Utilities are also required to maintain a detectable residual at all points in the distribution system.
How to filter chlorine
Not all filters address chlorine. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.
Frequently asked questions
What is chlorine?
Chlorine is added to drinking water as a disinfectant to kill bacteria, viruses, and other pathogens. A residual amount remains in the water as it travels through the distribution system to prevent recontamination.
What are the health effects of chlorine?
At the levels found in tap water (typically 0.2–1.0 ppm), chlorine itself is not considered a significant health risk. The primary concern is that chlorine reacts with natural organic matter to form disinfection byproducts (TTHMs and HAA5) that do carry health risks. Chlorine can cause taste and odour complaints and may cause skin and eye irritation in sensitive individuals.
Is chlorine regulated in drinking water?
EPA sets an MCL of 4 ppm for chlorine residual and an MRDL (Maximum Residual Disinfectant Level) of 4 ppm. Utilities are also required to maintain a detectable residual at all points in the distribution system.
Where does chlorine come from?
Added intentionally at the water treatment plant. Residual chlorine is required by EPA to remain in water throughout the distribution system. Levels are monitored continuously.
How do I remove chlorine from tap water?
The most effective methods for removing chlorine are: Activated carbon block filter, Granular activated carbon (GAC), Whole-home carbon filter, KDF (kinetic degradation fluxion) media. Look for NSF-certified systems—independent certification confirms removal claims have been verified.
Is chlorine in your water?
Enter your ZIP code to see the measured level in your specific utility.