What does chlorine residual refer to?

Chlorine residual refers specifically to the amount of chlorine that remains in the water after the disinfection process has taken place. This residual is an important aspect of water treatment as it indicates that there is still an adequate level of chlorine present to effectively kill any remaining pathogens or bacteria in the water, ensuring its safety for consumption and use. It helps in maintaining water quality during distribution, as it prevents biological regrowth in the pipes.

Other options reflect different aspects of chlorine management. The amount of chlorine added before treatment relates to the initial dosage required for effective disinfection, but does not provide information on what remains after disinfection has occurred. The process of chlorine dilution is relevant to how chlorine is mixed with water but does not focus on the residual effects post-treatment. The total amount of chlorine in storage indicates the inventory held but, again, does not pertain to the residual present in the treated water system. Thus, the correct understanding of chlorine residual as the remaining chlorine after disinfection highlights its crucial role in ensuring ongoing water safety and quality.