The drainage system of the Harappan civilisation was carefully planned. It is considered to be one of the best features of Harappan town planning. In the Lower Town, roads and streets were laid out along a grid pattern which intersected at right angles. Streets with drains were laid out first and then residential houses were built along them. The town planning was so perfect that waste water from every household was made to flow into the drains. The drains were not left open. They were covered with loose bricks. Sanitation and hygiene were also taken care of by the town planners.