Prohibits any state or county law, rule, ordinance, or regulation from requiring the addition of any substance, product, or chemical for preventative health care or medical purposes, that is unrelated to chemicals necessary for protection against contamination of drinking water, to any public water system. Establishes quality control and public safety requirements if the Safe Drinking Water Act is amended to authorize a federal regulation to allow every state to use the drinking water system to dispense chemicals or medication for treating the physical or mental function of a person's body.