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Issues that affect water supply and sanitation in the United States include 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.〔, p. 11〕 As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates 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. Eleven percent of Americans receive water from private (so-called "investor-owned") utilities. In rural areas, cooperatives often provide drinking water. Finally, up to 15 percent of Americans are served by their own wells. Water supply and wastewater systems are regulated by state governments and the federal government. At the state level, health and environmental regulation is entrusted to the corresponding state-level departments. Public Utilities Commissions or Public Service Commissions regulate tariffs charged by private utilities. In some states they also regulate tariffs by public utilities. At the federal level, drinking water quality and wastewater discharges are regulated by the United States Environmental Protection Agency, which 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 sewerage.〔Calculated based on a median household income of $42,409 in 2002, as quoted by 〕 ==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.〔Steven J. Burian, Stephan J. Nix, Robert E. Pitt, and S. Rocky Durrans:(Urban Wastewater Management in the United States:Past, Present, and Future ), in:Journal of Urban Technology, 2000, Volume 7, Number 3, pages 33-62. Retrieved July 26, 2010.〕 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. For decades federal funding for water supply and sanitation was provided through grants to local governments. After 1987 the system was changed to loans through revolving funds. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Water supply and sanitation in the United States」の詳細全文を読む スポンサード リンク
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