What is the purpose of residual chlorine in treated water?

Residual chlorine in treated water serves an essential purpose in maintaining water quality after it has been treated. Specifically, it acts as a disinfectant that helps to prevent the growth of harmful bacteria and other microorganisms that could recontaminate the water supply as it travels through the distribution system. By ensuring that there is a specific level of chlorine remaining in the water after treatment, it provides a continuous barrier against potential contaminants that might enter the water system following the initial treatment process.

This residual effect is crucial for safeguarding public health, as it assures that the water remains safe for consumption and use until it reaches consumers. While other factors like taste, cost efficiency, or visual appearance may play roles in overall water treatment considerations, the primary and most critical function of residual chlorine is its protective effect against recontamination.