<P> In 1987 Congress passed the Water Quality Act, which replaced the construction grant program with a system of subsidized loans using the Clean Water State Revolving Fund (CWSRF). The intention at the time was to completely phase out federal funding after a few years . Funding peaked in 1991 and continued at high levels thereafter, despite the original intentions . New challenges arose, such as the need to address combined sewer overflows for which EPA issued a policy in 1994 . In 1996 Congress established the Drinking Water State Revolving Fund, building on the success of the CWSRF, in order to finance investments to improve compliance with more stringent drinking water quality standards . </P> <P> This section provides a brief overview of the water supply and sanitation infrastructure in the U.S., water sources of some of the main cities, and the main types of residential water use . </P> <P> The centralized drinking water supply infrastructure in the United States consists of dams and reservoirs, well fields, pumping stations, aqueducts for the transport of large quantities of water over long distances, water treatment plants, reservoirs in the distribution system (including water towers), and 1.8 million miles of distribution lines . Depending on the location and quality of the water source, all or some of these elements may be present in a particular water supply system . In addition to this infrastructure for centralized network distribution, 14.5% of Americans rely on their own water sources, usually wells . </P> <P> The centralized sanitation infrastructure in the U.S. consists of 1.2 million miles of sewers--including both sanitary sewers and combined sewers, sewage pumping stations and 16,024 publicly owned wastewater treatment plants . In addition, at least 17% of Americans are served by on - site sanitation systems such as septic tanks . </P>

Where do most cities get their water supply