Science
The Science of Hâ‚‚O
The Water Cycle
The most comprehensive explanation of Earth's water-cycle components, with diagrams in 60+ languages
What Makes Water Water?
Sure, water is wet...but it is a whole lot more. Learn about water's properties.
Welcome to the Science Topics page of the USGS Water Science School, where you can explore the many aspects of water. All of our science information is available by browsing the Themes below.
Groundwater
Science Topics
FAQs
What is the Earth's "water cycle?" What is the Earth's "water cycle?"
The water cycle, also known as the hydrologic cycle, describes where water is stored on Earth and how it moves. Water is stored in the atmosphere, on the land surface, and below the ground. It can be a liquid, a solid, or a gas. Liquid water can be fresh or saline (salty). Water moves between the places it is stored. It moves at large scales (through watersheds, the atmosphere, and below the Earth...
How much of the Earth's water is stored in glaciers? How much of the Earth's water is stored in glaciers?
About 2.1% of all of Earth's water is frozen in glaciers. 97.2% is in the oceans and inland seas 2.1% is in glaciers 0.6% is in groundwater and soil moisture less than 1% is in the atmosphere less than 1% is in lakes and rivers less than 1% is in all living plants and animals. About three-quarters of Earth's freshwater is stored in glaciers. Therefore, glacier ice is the second largest reservoir...
How important is groundwater? How important is groundwater?
Groundwater, which is in aquifers below the surface of the Earth, is one of the Nation's most important natural resources. Groundwater is the source of about 37 percent of the water that county and city water departments supply to households and businesses (public supply). It provides drinking water for more than 90 percent of the rural population who do not get their water delivered to them from...
Education
Classroom Currents - Water Science School Newsletter Summer 2025 Classroom Currents - Water Science School Newsletter Summer 2025
Water Insights: Short Education Activities to Explore the NWAA Report Water Insights: Short Education Activities to Explore the NWAA Report
