Municipal water is processed at a water treatment facility before it’s delivered to the public, which should make it safe for residents to use.
Municipalities add chemicals to the water when it is treated. One of the most common chemicals used in water treatment is chlorine, which is used as a disinfectant to kill bacteria and other microbes. Sometimes chloramine, a combination of chlorine and ammonia, is also used.
A small, but potential risk of these chemicals comes from byproducts they create in the water when reacting with organic compounds. Those byproducts are trihalomethanes (THMs) and haloacetic acids (HAAs). Some studies indicate THMs and HAAs are linked to increase risk of serious health problems like cancer and heart disease.
However, it’s important to note that water quality would be much worse if municipalities did not use these chemicals to eliminate what could be harmful. The World Health Organization (WHO) says health risks from chlorine are small compared to the dangers of failing to properly disinfect public water.