What is the most commonly used water disinfectant in the United States?

Chlorine is the most commonly used water disinfectant in the United States due to its effectiveness and cost-efficiency. It has been utilized for many years in municipal water treatment processes to kill pathogenic microorganisms and ensure safe drinking water. Chlorine works by breaking down the cellular structure of bacteria and viruses, effectively rendering them inactive.

Moreover, chlorine's residual properties allow it to remain active within the distribution system, providing ongoing protection against microbial contamination as water moves from treatment facilities to consumers' taps. This residual effect is crucial for maintaining water quality and safety throughout the entire distribution system.

While other disinfectants, such as ozone and chlorine dioxide, are also effective and used in certain applications, they may not provide the same level of residual protection or are often more expensive and complex to manage. Bromine is primarily used in swimming pools and spas rather than in municipal drinking water systems.