Methods of rain water harvesting used in India are: (i) Guls and Kuls: People built guls and kuls in hilly and mountainous regions to divert water. These are simple channels. They are mainly used in the Western Himalayas. (ii) Roof top rain water harvesting: Commonly practised to store drinking water in Rajasthan. (iii) Inundation Channels: These channels developed in the flood plains of Bengal to irrigate fields. (iv) Khadins and Johads: In arid and semi-arid regions, some agricultural fields were converted into rain fed storage structures. These structures are found in Rajasthan. (v) Tankas: The tankas were built inside the main house or the courtyard. They were connected to the sloping roofs of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’. The first spell of rain was usually not collected as this would clean the roofs and the pipes.