“Chlorination is the process of adding chlorine to drinking water to disinfect it and kill germs. Different processes can be used to achieve safe levels of chlorine in drinking water. Chlorine is available as compressed elemental gas, sodium hypochlorite liquid solution or solid calcium hypochlorite. While the chemicals could be harmful in high doses, when they are added to water, they mix in and spread out, resulting in low levels that kill germs but are still safe to drink.” Chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm) are considered safe in drinking water. More information can be found on the Center for Disease Control and Prevention website.