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Drainage system of Indus Valley Civilization

The Indus civilization had an elaborate sanitary and drainage system, the hallmark of ancient Indus cities., The Authorities maintained a highly efficient drainage system.

Each house had horizontal and vertical drains.
There were underground drains for the streets.
These drains were covered by stone slabs.
The soak pits were made of bricks.
The house drains were connected with road drains.


Each and every house had a connection with the main drain. These even had inspection holes for maintenance. The conduits to the main drains running through the middle of the streets below pavement level and covered with flat stones and sturdy tile bricks. The covered drain was connected to the larger sewerage outlets which finally led the dirty water outside the populated areas. The urban plan found in these cities included the world’s first urban sanitationsystems. The elaborate brick-lined drainage system for the removal of rainwater is of unparalleled engineering skill.

According to D. D. Kosambi, the drainage plans of the Indus cities definitely establish the separate identity or independent character of the Indus civilization. No ancient civilization before the Roman civilization had such an advanced drainage and sanitation system.

[Manish Jain]

The Indus (Sanskrit—सिंधु, Greek—Sinthos; Latin—Sindus), along with its tributaries forms one of the largest drainage systems of the world. 
It is from this river that India got her name. The Indus valley has been the cradle of one of the oldest civilizations in the world—‘the Indus Valley Civilization’

The ancient Indus Valley Civilisation was prominent in hydraulic engineering and had many water supply and sanitation devices that were first of its kind.
Among the other things, they contain the world's earliest known flush toilets. These existed in many homes and were connected to a common sewerage pipe.
City walls functioned as barrier against floods.

Great Bath in Mohenjodaro is the earliest public water tank of the world. It measures 11.88 X 7.01 metres and has depth of 2.43 metres. Two wide staircases served as entry to the structure. A hole was found at one end of the bath which might have been used to drain water. The floor tank was made water tight by the use of gypsum plaster and bitumen.
The roads at that time cut each other at right angles and they had a remarkable arrangement of houses in the cities in form of grid pattern.

Almost every house in Mohenjo-Daro was equipped with a “bathroom”. This consisted of a shallow basin or platform, approximately 1 m2  in size, built of sharp-edged bricks which sloped towards an outlet connected to the street drain outside. Animal figurines retrieved from soakpits incorporated in house drainage systems may suggest a ritual significance for these elaborate bathing facilities, which could not have served the interests of hygiene alone. This interpretation is also the obvious one for the first known swimming pool in history: the Great Bath of Mohenjo-Daro. Consisting of a rectangular brick basin with a capacity of 160 m3
, and entered via a flight of steps at each narrow end, the Great Bath formed the center of an open inner courtyard enclosed within an imposing complex, some 1,800 m2
in area. The very fact that such a large pool was installed within the city points towards a veneration of water in a way that is familiar from other early developed urban civilizations

Water sewerage system
Perhaps the most impressive engineering feat accomplished by the people of the Indus Civilization in Mohenjo-Daro over 4,500 years ago is the network of effluent drains built of brick masonry, which served as the city’s sewerage system. The drains mostly ran along past the houses on one side of the generally unpaved streets, some 50 or 60 cm below street level. U-shaped in cross-section, the sides and bottoms of the drains were built of bricks set in clay mortar, while the open top could be covered in various ways. Obviously the width of the open top was dictated by the dimensions of the covering bricks, which ranged from 25 × 13 × 5.75 cm to 29.5 × 14.6 × 7.6 cm. The drains built of the smallest size bricks vary in width from 17 to 25 cm and in depth from 15 to 50 cm—that is, the equivalent of between two and eight brick courses. Thus the drains range from 260 cm2
to 1,200 cm2 in cross-section. The loose roofing could be removed for cleaning as required.


The drains sloped at a gradient of about 2 cm per meter and met at varying levels, depending on cross-section and period. Constructions on curves were sited in such a way that frictional loss was minimized. Wherever a drain had to traverse a longer distance or several drains met, a brick cesspit was installed; this was the simplest method to avoid clogging caused by solids settling. The effluent flowed into such a brick shaft at a high level, filled it, then flowed out the other side at a slightly lower level. The suspended matter gradually formed a deposit which could be removed via steps leading down into the pit, which was likely covered by a loose wooden roof


The Harappan town had very good drainage and sanitary system. The main drain was associated with each and every house ensuring the proper dumping of waste. In order to check the maintenance, inspection holes were provided. The drains were covered and connected to the bigger sewerage outlets, which ensured the channel of dirt out of the city

The bath and kitchen waters, as well as drainage from the latrines, and the roof drainage, usually did not run into the street drains direct, but entered them via tightly brick-lined puts, with outlets to the streets drains about three-quarters of the distance above the bottom.


The most unique aspect of planning during the Indus Valley civilization at Lothal was the system of underground drainage. The main sewer, 1.5 meters deep and 91 cm across, connected to many northsouth and east-west sewers. It was made from bricks smoothened and joined together seamlessly. The expert masonry kept the sewer watertight. Drops at regular intervals acted like an automatic cleaning device

[sumit patni]

The Indus Valley Civilization, which existed in the northwestern region of the Indian subcontinent around 3300–1300 BCE, had an advanced and well-planned drainage system. The cities of the Indus Valley Civilization, such as Mohenjo-daro and Harappa, had a highly organized system of brick-lined drains and sophisticated sewage disposal systems, which were built along with the houses and streets.

The drains were covered with brick or stone slabs and were designed to carry both surface runoff and sewage. They were also connected to underground sewer systems that were built beneath the streets. These sewer systems were designed to carry waste water from individual houses to a main sewer that ran through the center of each city. The waste water was then directed to an open drain or a nearby river.

This drainage system not only ensured that the cities remained hygienic and free from diseases but also provided a reliable source of water for daily use. The water from the Indus River was also used for irrigation and to support agriculture in the region.

Overall, the drainage system of the Indus Valley Civilization was a remarkable achievement, particularly considering the time period in which it was built. It demonstrated the advanced knowledge of engineering and hygiene that the people of the Indus Valley Civilization possessed.