Sanitary sewer

A sanitary sewer (also called, especially in the UK, a foul sewer) is a type of underground carriage system for transporting sewage from houses or industry to treatment or disposal. In some areas, sanitary sewers are separate sewer systems specifically for the carrying of domestic and industrial wastewater, and are operated separately and independently of storm drains, which carry the runoff of rain and other water which wash into city streets.

In the twenty-first century developed world, sewers are usually pipelines that begin with connecting pipes from buildings to one or more levels of larger underground horizontal mains, which terminate at sewage treatment facilities. Vertical pipes, called manholes, connect the mains to the surface. Sewers are generally gravity powered, though pumps may be used if necessary. The most commonly used sanitary pipe is SDR-35, with smaller sized laterals interconnected within a larger sized main.

History

The earliest covered sewers uncovered by archaeologists are in the regularly planned cities of the Indus Valley Civilization. In ancient Rome, the Cloaca Maxima, considered a marvel of engineering, disgorged into the Tiber. In medieval European cities, small natural waterways used for carrying off wastewater were eventually covered over and functioned as sewers. London's River Fleet is such a system. Open drains along the center of some streets were known as 'kennels' (= canals, channels). The nineteenth century brick-vaulted sewer system of Paris offers tours for tourists.

implified sewers

Simplified sanitary sewers consist of small-diameter pipes (typically 100 mm or about 4 inches), often laid at fairly flat gradients (1 in 200). The investment cost for sanitary sewers can be about half the costs of conventional sewers. However, the requirements for operation and maintenance are usually higher. Simplified sewers are most common in Brazil and are also used in a number of other developing countries.

ewers in popular culture

The image of the sewer recurs in European culture as they were often used as hiding places or routes of escape by the scorned or the hunted, including partisans and resistance fighters in WWII. The only survivors from the Warsaw Uprising and Warsaw Ghetto made their final escape through city sewers. Some have commented that the engravings of imaginary prisons by Piranesi were inspired by the Cloaca Maxima, one of the world's earliest sewers.

ewers in fiction

The theme of traveling through, hiding, or even residing in sewers is a common cliché in media, where unsanitary conditions or the strong smell of sewage are seldom mentioned. Famous examples of sewer dwelling or scenes are Teenage Mutant Ninja Turtles, Stephen King's "It", "The Third Man", "Mimic", "The Phantom of the Opera", and "Jet Set Radio Future"

ewer alligators

A well-known urban legend, the sewer alligator, is that of giant alligators or crocodiles residing in sewers, especially of major metropolitan areas. Two public sculptures in New York depict an alligator dragging a hapless victim into a manhole. [ [http://www.npr.org/templates/story/story.php?storyId=4111768 Subway Art: New York's Underground Treasures : NPR ] ]

Alligators have been known to get into combined storm sewers in the Southeastern United States. Closed-circuit television by a sewer repair company captured an alligator in a combined storm sewer on tape. [ [http://youtube.com/watch?v=Mzh1lhV_RXE YouTube - Bad sewer pipes across America ] ]

Notes

ee also

*Combined sewer
*Sanitary sewer overflow (SSO)
*Sewage treatment
*Stormwater
*Water pollution