Chlorine and chlorine dioxide are chemicals used to disinfect water. Chlorine, commonly applied as gas or liquid bleach, effectively eliminates bacteria and viruses in water. Chlorine dioxide, another disinfectant, also kills various microorganisms without forming harmful byproducts. These chemicals are crucial in water treatment plants to ensure that harmful pathogens are removed from water, making it safe for drinking and preventing the spread of waterborne diseases, safeguarding public health.