The oversight and safety of public drinking water in the U.S. is of such high quality that in the vast majority of cases little medical need exists for the public to choose bottled water over public drinking water other than convenience and social habit.
Although bottled water is generally no healthier or safer than most tap water, consumers are paying 1000-2000 times the cost of tap water to obtain bottled water, which in many cases is simply municipal water that has been subject to additional treatment. Read the AMA Council on Science and Public Health Report on “Safety of Bottled Water”.