Just like most civilizations water was needed for agriculture which was the main economic activity and humans needed in order to survive. Wastewater management. Contaminated water and poor sanitation leads to disease transmission. Water management tools were used to transport items for trade and were valuable for personal hygiene.

Waste water was collected through terracotta pipes into a sump and removed contaminants then into drainage channels that led to the streets. Extensive networks of reservoirs, wells, and canals were used as water harvesting techniques. Recent discoveries found tools rain catchments that were hewn from solid rock to catch monsoon rains. 

There was a sanitation system that was designed to prevent the spread of diseases. Having clean streets and wastewater being removed from homes helped cities stay healthier and habitable. The plumbing systems made the civilization carefully designed. 

The great bath is the oldest public tank in the ancient world. It's 12 meters long and 7 meters wide with a depth of 2.4 meters. The tank is finely lined bricks on the edge with gypsum plaster. Many archaeologist believe that the "Great Bath" was used for religious practices to purify and renew the well being of the bathers.