Water supply and sanitation in the United States involves a number of issues including water scarcity, pollution, a backlog of investment, concerns about the affordability of water for the poorest, and a rapidly retiring workforce. Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. Droughts are likely to particularly affect the 66 percent of Americans whose communities depend on surface water. (Quoting ) As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates, PFAS and pharmaceutical substances, but generally drinking water quality in the U.S. is good.

Cities, utilities, state governments and the federal government have addressed the above issues in various ways. To keep pace with demand from an increasing population, utilities traditionally have augmented supplies. However, faced with increasing costs and droughts, water conservation is beginning to receive more attention and is being supported through the federal WaterSense program. The reuse of treated wastewater for non-potable uses is also becoming increasingly common. Pollution through wastewater discharges, a major issue in the 1960s, has been brought largely under control.

Most Americans are served by publicly owned water and sewer utilities. Public water systems, which serve more than 25 customers or 15 service connections, are regulated by the U.S. Environmental Protection Agency (EPA) and state agencies under the Safe Drinking Water Act (SDWA). Eleven percent of Americans receive water from private (so-called "investor-owned") utilities. In rural areas, cooperatives often provide drinking water. Finally, over 13 million households are served by their own wells. The accessibility of water not only depends on geographical location, but on the communities that belong to those regions. Of the millions who lack access to clean water, the majority are low-income minority individuals. Wastewater systems are also regulated by EPA and state governments under the Clean Water Act (CWA). Public utilities commissions or public service commissions regulate tariffs charged by private utilities. In some states they also regulate tariffs by public utilities. EPA also provides funding to utilities through state revolving funds.

Water consumption in the United States is more than double that in Central Europe, with large variations among the states. In 2002 the average American family spent $474 on water and sewerage charges, which is about the same level as in Europe. The median household spent about 1.1 percent of its income on water and sewage. By 2018, 87% of the American population receives water from publicly owned water companies.

History

In the 19th century numerous American cities were afflicted with major outbreaks of disease, including cholera in 1832, 1849 and 1866 and typhoid in 1848. The fast-growing cities did not have sewers and relied on contaminated wells within the city confines for drinking water supply. In the mid-19th century many cities built centralized water supply systems. However, initially these systems provided raw river water without any treatment. Only after John Snow established the link between contaminated water and disease in 1854 and after authorities became gradually convinced of that link, water treatment plants were added and public health improved. Sewers were built since the 1850s, initially based on the erroneous belief that bad air (miasma theory) caused cholera and typhoid. It took until the 1890s for the now universally accepted germ theory of disease to prevail.

However, most wastewater was still discharged without any treatment, because wastewater was not believed to be harmful to receiving waters due to the natural dilution and self-purifying capacity of rivers, lakes and the sea. Wastewater treatment only became widespread after the introduction of federal funding in 1948 and especially after an increase in environmental consciousness and the upscaling of financing in the 1970s. From 1948 to 1987 federal funding for sanitation was provided through grants to local governments. Congress amended the CWA in 1987 and changed the funding system for sewage treatment to loans through revolving funds. Congress added a state revolving fund for drinking water utilities to the SDWA in 1996.

Piped water supply until 1948

In the 1840s and 1850s the largest cities in the U.S. built pipelines to supply drinking water from rivers or lakes. However, the drinking water was initially not treated, since the link between waterborne pathogens and diseases was not yet well known. In 1842 New York City was one of the first cities in the U.S. to tap water resources outside the city limits. It dammed the Croton River in Westchester County, New York, and built an aqueduct from the reservoir to the city. Also in 1842, construction was completed on Chicago's first water works, with water mains made of cedar and a water intake located about into Lake Michigan.City of Chicago Water Department:Water History. Retrieved July 26, 2010. In 1848, Boston began construction of a water transmission system. A tributary of the Sudbury River was impounded creating Lake Cochituate, from where the Cochituate Aqueduct transported water to the Brookline Reservoir that fed the city's distribution system. In 1853, Washington, D.C., followed suit by beginning the construction of the Washington Aqueduct to provide water from the Great Falls on the Potomac River.

In 1854, the British physician John Snow found that cholera was spread through contaminated water. As a result of his findings, several cities began to treat all water with sand filters and chlorine before distributing it to the public. Before efforts to clean drinking water were implemented at the turn of the 20th century, mortality among 1- to 5-year-olds in the United States in some major river cities was nearly one in five. Clean water is estimated to have reduced about three-fourths of infant mortality, and two-thirds of child mortality. By 1900, sand filtration was widely used. In 1908, the first continuous application of chlorination to drinking U.S. water was in Jersey City, New Jersey (and not without controversy). Cities also began to construct sewers in the late 19th century. As a result of water treatment and sanitation, the incidence of cholera and typhoid rapidly decreased. Slow sand filtration was initially the technology of choice for water treatment, later being gradually displaced by rapid sand filtration. As a result of the water purification efforts, mortality among black infants declined in particular, leading to a 13 percent reduction in the black-white infant mortality gap.

In the arid American Southwest, the water demand of rapidly growing cities such as Los Angeles exceeded local water availability, requiring the construction of large pipelines to bring in water from far-away sources. The most spectacular example is the first Los Angeles Aqueduct built between 1905 and 1913 to supply water from the Owens Valley over a distance of 233 mi (375 km).

Drinking water quality standards were first issued in 1914 by the United States Public Health Service. However they were only enforceable for interstate transportation carriers (such as railroads) at specific points where water was transferred.

Sanitation until 1948

Most of the first sewer systems in the United States were built as combined sewers (carrying both storm water and sewerage). They discharged into rivers, lakes and the sea without any treatment. The main reason for choosing combined sewers over separate systems (separating sanitary sewers from storm water drains) was a belief that combined sewer systems were cheaper to build than separate systems. Also, there was no European precedent for successful separate sewer systems at the time. The first large-scale sewer systems in the United States were constructed in Chicago and Brooklyn in the late 1850s, followed by other major U.S. cities.

Few sewage treatment facilities were constructed in the late 19th century to treat combined wastewater because of the associated difficulties. There were only 27 U.S. cities with wastewater treatment works by 1892, most of them "treating" wastewater through land application. Of these 27 cities, 26 had separate sanitary and storm water sewer systems, thus facilitating wastewater treatment, because there was no need for large capacities to accommodate wet weather flows. Furthermore, there was a belief that the diluted combined wastewater was not harmful to receiving waters, due to the natural dilution and self-purifying capacity of rivers, lakes and the sea. In the early 20th century a debate evolved between those who thought it was in the best interest of public health to construct wastewater treatment facilities and those who believed building them was unnecessary. Nevertheless, many cities began to opt for separate sewer systems, creating favorable conditions for adding wastewater treatment plants in the future.

Where wastewater was being treated it was typically discharged into rivers or lakes. However, in 1932, the first reclaimed water facility in the U.S. was built in Golden Gate Park, San Francisco, for the reuse of treated wastewater in landscape irrigation.

Sanitary sewers were not the only sanitation solution applied. They were particularly useful in high-density urban areas. However, in some newly built lower-density areas, decentralized septic systems were built. They were attractive because they reduced capital expenditures and had fewer operation and maintenance costs compared to wastewater treatment plants.

After 1948: Federal government

In the first half of the 20th century water supply and sanitation were a local government responsibility with regulation at the state level; the federal government played almost no role in the sector at that time. This changed with the enactment of the Federal Water Pollution Control Act of 1948, which provided for comprehensive planning, technical services, research, and financial assistance by the federal government to state and local governments for sanitary infrastructure. The Act was amended in 1965, establishing a uniform set of water quality standards and creating a Federal Water Pollution Control Administration authorized to set standards where states failed to do so.