Some systems use surface water from a river or lake and serve millions of urban customers.
Others use wells or ground water and serve only a few dozen visitors to a campground or gas station. EPA regulations help to guarantee that Americans find safe drinking water everywhere in the country. In order to best manage these water systems and their widely different local conditions, EPA allows states to directly supervise water systems within their borders. The database contains general information as well as the technical details of a water system's violation of water quality regulations. Other information describes enforcement actions taken by regulatory agencies and the results of water testing done for a water system.