What is the minimum free chlorine residual required throughout a water distribution system in mg/l?

The minimum free chlorine residual required throughout a water distribution system is 0.5 mg/l. This level is considered essential to effectively ensure that the water remains microbiologically safe as it travels through the distribution network. Free chlorine acts as a disinfectant, helping to kill or inactivate pathogens that could compromise public health.

A free chlorine residual of 0.5 mg/l is established as a balancing point that provides adequate disinfection while limiting the potential for taste or odor issues often associated with higher concentrations of chlorine. Maintaining this minimum level helps ensure that the safety and quality of drinking water are upheld without producing adverse sensory effects for consumers.