Learn about water

The water cycle describes where water is on Earth and how it moves. Human water use, land use, and climate change all impact the water cycle. By understanding these impacts, we can work toward using water sustainably.

Looking at water, you might think that it's the simplest thing around. Pure water is practically colorless, odorless, and tasteless. But it's not at all simple and plain and it is vital for all life on Earth. Where there is water there is life, and where water is scarce, life has to struggle or just "throw in the towel." Continue on to learn about dozens of water properties.

What is in that water that you just drank? Is it just hydrogen and oxygen atoms? Is it safe for drinking? All water is of a certain "quality" (and you can't tell by just looking), but what does "water quality" really mean?

The world's surface-water resources—the water in rivers, lakes, and ice and snow—are vitally important to the everyday life of not only people, but to all life on, in, and above the Earth. And, of course, surface water is an intricate part of the water cycle, on which all life depends.

Groundwater is one of our most valuable resources—even though you probably never see it or realize it is there. There is water somewhere beneath your feet no matter where on Earth you live.

Water is everywhere, which is fortunate for all of humanity, as water is essential for life. Even though water is not always available in the needed quantity and quality for all people everywhere, people have learned to get and use water for all of their needs, from drinking, cleaning, irrigating crops, producing electricity, and for just having fun.