Rainwater harvesting is the crying need of the day. It is said that if the third world war is to be fought, it will be fought for water. A huge quantity of rainwater goes down the drain every year. Every home, every village, and every city should have a rainwater harvesting system. Rainwater that comes on roofs of our houses, can be used to refill groundwater. Rainwater harvesting saves us from floods. It saves bays, seas, and oceans from overflowing. It maintains the groundwater level. In the desert area, it makes available precious water around the year. It can be used for irrigation, too. Thus, the harvesting of rainwater is the immediate need of the hour.