Why is chlorine often used in water systems?

Chlorine is commonly used in water systems primarily because it serves as an effective disinfectant. Its ability to kill harmful microorganisms, including bacteria, viruses, and other pathogens, makes it an essential component in ensuring water safety. By utilizing chlorine, water treatment facilities significantly reduce the risk of waterborne diseases, providing safe drinking water to the public.

While other options might touch on benefits related to water treatment, they do not pertain directly to the primary purpose of chlorine in this context. For instance, chlorine does not significantly affect water hardness, enhance taste, or improve clarity in a way that its disinfectant properties do. Thus, the effectiveness of chlorine as a disinfectant is the primary reason for its widespread use in water systems.