What is the minimum chlorine residual required in a distribution system?

The minimum chlorine residual required in a distribution system is typically set to ensure that there is enough disinfection capacity to prevent the growth of pathogens and maintain water quality throughout the system. A residual of 0.2 mg/L is recognized as a standard threshold that effectively provides a balance of safety and efficiency.

At this level, sufficient disinfectant remains in the system to thwart any potential microbial growth that may occur due to recontamination in the distribution pipes, thus contributing to public health safety. Ensuring this minimum level is crucial in maintaining the integrity of the water supply from treatment plants to consumers.

While some other values may be used in different contexts or regions, 0.2 mg/L effectively serves as a practical minimum requirement. This is based on industry best practices and regulations to ensure safety without causing excessive chlorine taste or odor, which can be a concern at higher concentrations.