(i) The tanks could be as large as a big room; one household in Phalodi had a tank that was 6.1 meters deep, 4.27 meters long and 2.44 meters wide. (ii) The tankas were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard. (iii) They were connected to the sloping roofs of the houses through a pipe. (itv) Rain falling on the rooftops would travel down the pipe and was stored in these underground tankas. (v) The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected.