No, chloride (Cl-) is not used directly to kill bacteria in public water. It's chlorine (Cl2) that is used as a disinfectant to kill bacteria, viruses, and other microorganisms.

Here's why:

* Chlorine gas (Cl2) is a powerful oxidizer that can kill harmful microbes by disrupting their cellular processes. When added to water, it forms hypochlorous acid (HOCl), which is the active disinfecting agent.

* Chloride (Cl-) is a negatively charged ion that is a naturally occurring element found in water. While it plays a role in the overall water chemistry and can impact the effectiveness of chlorine, it's not the active disinfectant itself.

In summary, chlorine is the disinfectant used in public water to kill bacteria, while chloride is a naturally occurring ion that plays a role in the overall water chemistry.