What is the minimum combined chlorine residual required in drinking water?

The minimum combined chlorine residual required in drinking water is generally set to ensure effective disinfection and to maintain a sufficient level of chlorine in the distribution system. A residual chlorine concentration of 0.6 mg/L is recognized as effective for providing adequate microbial protection while minimizing the risk of harmful pathogens present in the water supply.

This concentration is important because it strikes a balance between being high enough to effectively disinfect any contaminants that may be present and low enough to avoid potential health risks associated with chlorine byproducts. The target level of 0.6 mg/L is also consistent with various public health guidelines that aim to ensure safe drinking water standards.

Higher levels, while still effective, may lead to increased formation of byproducts, which are not desirable for long-term water quality. Thus, maintaining the combined chlorine residual at around 0.6 mg/L serves as a widely accepted benchmark in water treatment practices.