The most striking feature of this Harappan civilization (Indus Valley Civilization) is that the Indus Valley people had constructed their drainage system on very scientific lines.
The drainage system of Mohen-jo-daro is so elaborate that “the like of which has not yet been found anywhere in the world in any other city of the same antiquity.”
House drains emptied themselves into the main drains which ran under the main streets and below many lanes. The Harappan people well knew that such drains were not to be left open.
The drainage system and drains were covered with bricks or stones and were provided with inspection traps and main holes at regular intervals for inspection. Every care was taken that the house-wives did not throw refuse or dirt in the drains. Every house had its own soak-pit which collected all the sediments and allowed only the water to flow into the street drain. The elaborate drainage system of the Harappan people shows that they had developed a high sense of health and sanitation.