Allegheny County Sanitary Authority

Allegheny County Sanitary Authority (also known as ALCOSAN) is a Municipal Authority in Allegheny County, Pennsylvania that provides wastewater treatment services to 83 communities, including the city of Pittsburgh. Its principal sewage treatment plant is along the Ohio River downstream from Pittsburgh (see satellite photo). (map of service area)

In Pittsburgh's early history, the Allegheny and Monongahela rivers were used as both drinking water sources and as sewers. While the rich often drank bottled water, the poor used primarily unfiltered river water. Pittsburgh at one time had the highest rate of typhoid in the country; in the late 19th century, about half of all foreign-born men became sick with typhoid within two years of arriving in the city. Typhoid death rates dropped from about 130 per 100,000 population to about 30 per 100,000 after filtration of the water supply began in 1907.

As the city's population grew, its early haphazard collection of cesspools and privy vaults (outhouses) was replaced with a municipal combined sewer system that routed sewage into the area's tributaries and rivers, starting around 1880. This improved many neighborhoods, but it deflected the problem into the rivers. Although the Pennsylvania Pure Waters Act of 1905 banned the discharge of untreated sewage by any new municipal system, that practice continued in Pittsburgh. Public health experts advocated for sewage treatment in the early 20th century, but this was regarded as an unaffordable luxury by most. Disease rates had dropped in the meantime, typhoid deaths being reduced to under 1 case per 100,000 by the 1930s. The prevailing attitude was that rivers were created in order to carry waste to the sea, and that rather than require Pittsburgh to treat its wastewater, communities downriver should treat their water supplies.

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