Nature recycles water all the time. Water in oceans, lakes, and rivers evaporates, or turns into a gas and rises into the air. The water vapor eventually turns back into a liquid and falls as rain. The water cycle keeps the total amount of water on Earth the same. But most of this water is salt water in the ocean. People need fresh water for drinking and for growing food on farms. Ocean water is too salty to drink. It is too salty to use for watering plants.

Some places have more fresh water than others. People who live near big lakes or rivers have more fresh water than people who live in the desert. Places where a lot of rain falls have more fresh water.

Places that usually have enough fresh water sometimes have a drought. Very little rain falls during a drought. People run short of water. People everywhere should be careful not to waste water.