General information

The Water Cycle

Geologic Time

The water you drank this morning might have been the same water that once rained down on a Tyrannosaurus, froze on a woolly mammoth, flowed down the Nile to bring new silt to an Egyptian farm – or filled the bathing pool of Julius Caesar. The water we use now is the same supply that has been on Earth for billions of years. Its quality is renewed again and again by the natural water (hydrologic) cycle.

Water itself is the only substance that exists in liquid, gas and solid form – the keys to the water cycle. Here’s how the cycle works:

Water evaporates from oceans, rivers and lakes (water in its liquid form) and rises into the atmosphere (water in its gas form) where it condenses to form clouds. Precipitation then falls to the earth in the form of rain (water in its liquid) or snow (water in its solid form) where it flows into oceans, rivers and lakes and the process begins again.

Water is the most precious renewable resource on Earth, defining our planet as a glowing blue marble floating in the frozen black of space. Life cannot exist without water – this includes humans who cannot live more than a few days without water. Although water covers 71 percent of the Earth’s surface, fresh water is limited – 97% is salt water. Of the remaining 3%, less than 1% is the fresh water that flows in our streams and lakes or is stored in our groundwater aquifers.

Related

Maps & Posters

Water Cycle Poster

Water as a renewable resource is depicted in this 18×24 inch poster. Water is renewed again and again by the natural hydrologic cycle where water evaporates, transpires from plants, rises to form clouds, and returns to the earth as precipitation. Excellent for elementary school classroom use.

Product

KIDs: The Water Story

For ages 8-12, this colorful, 16-page activity book features games and exercises to introduce water artifacts and cultural celebrations, water friendly cleaning alternatives, and the maze from water source through treatment plant to homes and out again. Part of the KIDs Series, published by The Project WET International Foundation.

Referring Pages

Commands