The health department requires a minimum of how much free chlorine residual at distant points of the distribution system?

The minimum required free chlorine residual at distant points in a water distribution system is set to ensure that there is an adequate level of disinfectant present to protect public health throughout the entire system. A threshold of 0.2 ppm is recognized as effective for maintaining a residual that can combat bacteria and other pathogens, thus ensuring water safety and quality for consumers.

This level strikes a balance, as it is sufficient to suppress microbial growth while minimizing any potential negative effects on taste or odor that higher concentrations might introduce. Maintaining a free chlorine residual at this level throughout the distribution system is essential for prolonged protection against contamination as the water travels from treatment facilities to end users.