Video: Earth’s Water Budget

Earth’s 370 quintillion gallons of water can be found all over the planet in lakes, rivers, glaciers, oceans, and groundwater. However, only a tiny fraction of this water is usable by humans. Understanding Earth’s "water budget" – where these different forms of water exist and how they move – is an important part of understanding our planet and planning for future water needs. NASA has a fleet of satellites to help us bring Earth’s water budget into focus, including SWOT (Surface Water and Ocean Topography).