(i) The tankas were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard. They are built for storing drinking water. A tank could be 6.1 meters deep, 4.27 meters long and 2.44 meters wide. (ii) The tankas were built in the semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer.