While chlorine and other disinfectants keep tap water free of deadly pathogens, their chemical byproducts carry uncertain risks.
In the United States, 90 percent of Americans get the water they need from public drinking water systems that harbor disinfection byproducts, most of which are unregulated and understudied.
Disinfection byproducts form as a result of chemical treatments that water companies use to keep water free of dangerous pathogens. Some byproducts may increase the risk of cancer.