What is the Earth's "water cycle?"

The water cycle, also known as the hydrologic cycle, describes the continuous movement of water as it makes a circuit from the oceans to the atmosphere to the Earth and on again.

Most of Earth's water is in the oceans. The sun, which drives the water cycle, heats water in the oceans. Some of it evaporates as vapor into the air. Rising vapor cools and condenses into clouds. Cloud particles grow and fall out of the sky as precipitation.

Some precipitation accumulates as ice caps, glaciers, and snowpacks; in warmer climates, snow melts in the spring and flows into streams. Most precipitation falls back into the oceans or onto land, where it flows over the ground as surface runoff. A portion of runoff enters rivers and continues toward the oceans. Runoff and groundwater seepage can also accumulate and get stored as freshwater in lakes.

Some runoff soaks into the ground where it replenishes groundwater aquifers or seeps back to the surface. 

Over time, this cycle continues again and again.

Learn more: USGS Water Science School: The Water Cycle



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How much water is used by people in the United States?

Since 1950, the USGS has collected and analyzed water-use data for the United States and its Territories . That data is revised every 5 years. As of 2015, the United States uses 322 billion gallons of water per day (Bgal/day). The three largest water-use categories were irrigation (118 Bgal/day), thermoelectric power (133 Bgal/day), and public...

How much natural water is there?

Earth is estimated to hold about 1,460,000,000 cubic kilometers of water. The breakdown of where all that water resides is estimated as follows: Oceans (saline) 1,419,120,000 cubic kilometers Ice caps and glaciers (fresh) 31,244,000 cubic kilometers Groundwater (fresh and saline) 8,906,000 cubic kilometers Streams and lakes (fresh) 132,860 cubic...

How do we benefit from USGS streamgages?

Information on the flow of rivers is a vital national asset that safeguards lives, protects property, and ensures adequate water supplies for the future. The USGS is the federal agency responsible for operating a network of about 7,000 streamgages nationwide. Data from this network are used by water managers, emergency responders, utilities,...

What is groundwater?

Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table. Contrary to popular belief, groundwater does not form underground rivers. It fills the pores and fractures in underground materials such as sand, gravel, and other rock, much the same way that...
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Date published: December 14, 2016

How Much Water Do We Use?

The USGS National Water-Use Science project has documented 60 years of water-use from 1950 to 2010 in an interactive map.  Choose a year and pick a category to see how much water your state uses. 

Attribution: Water Resources
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The Natural Water Cycle
October 16, 2019

The Natural Water Cycle (JPG)

The Natural Water Cycle

Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over

El ciclo natural del agua, The natural water cycle, Spanish
October 7, 2019

El Ciclo del Agua - The Water Cycle, Spanish

El Ciclo del Agua

El ciclo del agua describe la presencia y el movimiento del agua en la Tierra y sobre ella. El agua de la Tierra esta siempre en movimiento y constantemente cambiando de estado, desde líquido, a vapor, a hielo, y viceversa. El ciclo del agua ha estado ocurriendo por billones de años, y la vida sobre la Tierra depende de él; la

All water on Earth in a sphere, placed over a "dry" globe
July 16, 2019

All of Earth's water in a single sphere!

This image shows blue spheres representing relative amounts of Earth's water in comparison to the size of the Earth. Are you surprised that these water spheres look so small? They are only small in relation to the size of the Earth. These images attempt to show three dimensions, so each sphere represents "volume." They show that in comparison to the volume of the globe,

The Water Cycle for Schools and Kids
April 10, 2019

The Water Cycle for Schools and Kids

Learn About Water!

The U.S. Geological Survey (USGS) and the Food and Agriculture Organization of the United Nations (FAO) have teamed up to create a water-cycle diagram for schools and kids. It is available in over 30 languages and also in an interactive version made for online

 El Ciclo del Agua Para Niños, The Water Cycle for Schools, Spanish
February 25, 2018

El Ciclo del Agua Para Niños, The Water Cycle for Schools, Spanish

El Ciclo del Agua Para Niños

El Servicio Geológico de los Estados Unidos (USGS por sus siglas en inglés) y la Organización de Alimento y Agricultura de las Naciones Unidas (FAO) han colaborado en la creación de un diagrama sobre el ciclo del agua para niños de las escuelas elementales e intermedias.

El Ciclo del Agua

Qué es el ciclo

Diagram of the Water Cycle
April 18, 2016

Diagram of the water cycle, showing natural and human processes

Diagram of the water cycle showing natural and human processes.

Le Cycle de l'Eau, The Water Cycle for Schools, French
February 19, 2017

Le Cycle de l'Eau - The Water Cycle, French (PDF)

Le Cycle de l'Eau pour les Enfants

Vous pouvez penser que chaque goutte de pluie qui tombe du ciel, ou chaque verre d'eau que vous buvez, est tout nouveau, mais, en fait, il a toujours été là et fait partie du cycle de l'eau.