What is the minimum chlorine residual required in the far reaches of a distribution system for public water systems?

The minimum chlorine residual required in the far reaches of a distribution system for public water systems is crucial for maintaining water quality. A residual of 0.2 mg/l of free chlorine is established as adequate to ensure that water remains safe and microbiologically stable as it travels through the distribution system. This level is effective in providing disinfection and preventing the regrowth of bacteria in the pipelines.

In practical terms, maintaining this minimum residual helps ensure that any pathogens present are effectively controlled and that the public receives water that meets safety standards. Chlorine serves as both a primary disinfectant and a residual agent, and this level strikes a balance between effective disinfection and regulatory compliance.

While options mentioning chloramines focus on a different type of disinfection, the correct answer specifically pertains to free chlorine, which is a standard for many public water systems. Chloramines, although they can provide residual disinfection, are not the point of focus in this context. Thus, focusing on the correct minimum residual for free chlorine ensures water quality and safety for consumers.