The amazing feats of engineering built centuries ago by the people of India's Golden Desert to harvest water, are still used today -- and are often superior to modern water mega-projects.
Ancient Indian water harvesting techniques of the Golden desert area in Rajasthan had unique mechanisms to store rain water. They barely received sufficient rainfall but still managed to cache enough water for all the towns in the region to not just survive, but flourish. The water table being 300 feet deep and full of salinity; hand pumps were of no use, and with no electricity, it was a marvel of human innovation that they thrived for centuries. Decades of non-usage and decay, has led to their need for reconstruction. Modern intervention with projects running into multiple crores, failed miserably as their approach was not suitable to such an environment. People there still use whatever is left of the ancient harvesting structures to sustain themselves.