Chlorine is technically a naturally occurring gas that can be found on the right side of the periodic table, but with regards to practical applications in water, it’s used to disinfect water in a process called chlorination. It’s common knowledge that this is used in swimming pools, but it’s also done in your drinking water to prevent you from drinking nasty microbes that will make you sick.
Unlike lead, it’s put there on purpose. Chlorination is part of the water treatment process that makes water safe for people to drink. It can be done at different points in the process, with a variation of chlorine-containing compounds, and the goal is, as mentioned, to deactivate pathogens in the water that can make you sick.
Chlorine can actually be an extremely dangerous material, but it isn’t dangerous in your drinking water because of the low concentrations it exists in. According to the CDC, water with a concentration of chlorine of 4 parts per million is safe to drink. Believe it or not, the primary concern with chlorine is actually the effects it has on taste and odor.
Chlorinated water can have a metallic taste to it that you may find unpleasant, and an odor to go with it. This comes from what’s known as residual chlorine, which remains in the water as it travels to your home in order to protect against pathogens it may encounter along the way.
Chlorine can be filtered out. It doesn’t need to be for health reasons, but you may find it tastes better with a filter that removes high amounts of chlorine, something you can do with an activated carbon fridge filter. A refrigerator water filter certified to meet NSF 40 standards will remove the taste and odor of chlorine. Each Sip by Second Nature, for example, will filter out more than 50% of chlorine, not completely removing all of the disinfecting material, but capturing enough residual chlorine to improve taste and odor.