Why we install Rainwater tanks in new houses?

are you creating cisterns? What country are we talking about here?

Collected rainwater can be used for all household needs such as irrigation, gardening, toilets, laundry, washing the car and so much more. Rainwater, in its original state, is pure and free of all contaminants. It is not chemically treated as other sources of water. With frequent droughts and water scarcity, having a rainwater tank can be a great asset to any home. With the right filtration techniques, stored rainwater can be used for all your drinking and cooking needs. Another evolving trend is the installation of internal rainwater tanks that provide a natural cooling effect to indoor spaces during hot summers. By having a free source of water, it is possible to cut down on steep water bills.