What is the minimum chlorine concentration allowed in the drinking water distribution system?

The correct minimum chlorine concentration allowed in a drinking water distribution system is 0.2 mg/L. This level of chlorine is essential for maintaining adequate disinfection throughout the system, helping to prevent the growth of harmful bacteria and pathogens that could compromise water quality.

Proper chlorination ensures that residual chlorine remains in the water as it travels through pipes to consumers, which is key to effective water treatment. A minimum concentration of 0.2 mg/L strikes a balance between effectiveness and safety, as it is sufficient to provide disinfection without creating excessive amounts of chlorine byproducts that could pose health risks to consumers.

This standard is rooted in regulatory guidelines aimed at protecting public health while ensuring the water is safe to drink. Other concentrations, while important for different aspects of water treatment, do not meet the minimum standard required for effective disinfection in this context.