Eventually runoff collects in underground aquifers or lakes and rivers. This sets the stage for the next step called evaporation. As sunlight heats up the water, it changes form. Liquid water becomes water vapor. This vapor then rises up into the sky.
Water can also return to the sky through a plant activity called transpiration.
Once in the sky, the water vapor cools down and forms clouds in a process called condensation. This step brings the cycle full circle when the clouds produce rain. In this way the cycle repeats itself over and over again. People get water for daily use by drilling wells into the groundwater or storing water in lakes and reservoirs. Of course lake water is not always the cleanest stuff, so we must purify it first.