Water is an essential chapter for it covers concepts like usage of water, sources of water, the meaning of water cycle, the formation of clouds, effects of massive rainfall drought, conservation of water and rainwater harvesting. Water provides insights on the water as an essential thing for life along with an introduction to evaporation, condensation, rainfall, floods, droughts and water available for our use. Water cycle: It is a circulation of water through the process of evaporation or condensation as rain or snowfall. Water can exist in all the three states - solid, liquid and gas. Liquid state: The water that we use in everyday life is a liquid.