Final answer:
Chlorine is the most commonly used water disinfectant in the U.S., predominantly in the form of chlorine gas, sodium hypochlorite, or chloramines, for its strong antimicrobial effect in treating municipal drinking water.
Step-by-step explanation:
The most commonly used water disinfectant in the United States is chlorine. This chemical is frequently used in various forms, including chlorine gas, sodium hypochlorite, and chloramines, to disinfect municipal drinking water. Chlorine's effectiveness is due to its ability to act as a strong oxidant, producing hypochlorous acid when mixed with water, which has potent antimicrobial properties.
Chloramine is also widely utilized, especially because it can stay active in the water system longer than chlorine, providing prolonged disinfection as the water travels through the distribution system. While other methods like UV disinfection, chlorination with bleach after natural disasters, and alternative chemicals like sodium dichloroisocyanurate (NaDCC) are available, chlorine remains the primary choice for routine water treatment.