The Indus or Harappan Civilisation is distinguished from the other contemporary civilisations by its

One of the most remarkable features of the Indus valley civilization is that the city was provided with an excellent closed drainage system. Each house had its own drainage and soak pit which was connected to the public drainage. Brick laid channels flowed through every street. They were covered and had manholes at intervals for cleaning and clearing purposes. Large brick culverts with corbelled roofs were constructed on the outskirts of the city to carry excess water. Thus Indus people had a perfect underground drainage system. No other contemporary civilization gave so much attention to cleanliness.