Which chemical is most commonly used for disinfection in municipal water treatment?

Chlorine is the most commonly used chemical for disinfection in municipal water treatment due to its effectiveness in eliminating a wide range of pathogens, including bacteria, viruses, and protozoa. It works by penetrating the cell walls of microorganisms and disrupting their biological processes, ultimately leading to their death.

Chlorine is favored for several reasons: it is cost-effective, readily available, and provides a residual effect in the water supply, which means it continues to disinfect as water moves through the distribution system. This residual capability helps prevent recontamination during transit to consumers.

While other disinfectants like ozone, iodine, and hydrogen peroxide have specific applications and benefits—such as ozone being a potent oxidizer that does not leave a residual and is effective against resistant organisms, or iodine being a good disinfectant for travels and emergency situations—chlorine is recognized for its widespread use in municipal systems, making it the standard choice for large-scale water treatment processes.