From ArticleWorld

A Sewer is a term used for a channel or conduit that carries wastewater and storm water runoff from the source to a treatment plant or receiving stream. Sewers that carry waste water from peoples’ households as well as industrial and commercial waste are known as sanitary sewers; those that carry runoff from rain or snow are called storm sewers; while, sewers that process both kinds of water are known as combined sewers. Storm sewers may also be called storm drains since they carry rain water or water that overflows from people’s yards on to the roads and streets back to the ocean. This water is not required to be treated before it is released.


Archaeological remains of the earliest sewers have been found in the Indus Valley civilization sites in India. Interestingly these bear very close resemblance to the modern city sewers. Other sewage systems of yore that are worth mentioning are the Cloaca Maxima system of Rome that released water into the Tiber, London’s Fleet system and Paris’s brick vault system, which now serves as a tourist attraction.

Sewage system

Sewage pipes run from under each house and building and connect to the main lines of pipes, also called mains. These are horizontal pipes running under the roads and streets of cities. These horizontal mains connect to bigger mains which then carry the waste water on to various treatment plants for treatment before the clean water is released into rivers, streams and oceans. As a rule the sewage system is gravity powered, carrying free flowing water and wastes but when required pressurized sewers carry pumped waste waters under pressure.

The Local Authority is usually responsible for the sewers, which collect the effluent from various drains, the drains being the responsibility of the land owners.