Fresh water

Fresh water is any naturally occurring water with low amounts of dissolved salts and other substances. Unlike seawater, fresh water includes water from rivers, lakes, wetlands, and underground sources. It is essential for most plants, animals, and humans to survive.

Only a small part of Earth’s water is fresh water—less than 3% of all water on the planet. Much of this fresh water is frozen in places like Antarctica, while only a small amount is available for people to use. Fresh water is important for drinking, farming, and many other human activities, but it can become polluted or scarce if not managed carefully.

Fresh water is part of Earth’s natural water cycle. Water evaporates from oceans and lakes, forms clouds, and falls back to land as rainfall or snowfall. This process keeps refreshing our fresh water supplies. However, when people use more fresh water than the cycle can replace, problems like water shortages can occur. In some places, people have created ways to make seawater safe to drink or reuse wastewater, but these methods can be expensive and need a lot of energy.

Definitions

Fresh water is water with very little salt in it—usually less than 500 parts per million. Some experts say fresh water can have even more salt, up to 1,000 or 3,000 parts per million.

Fresh water can be found in many places. It can be still, like in ponds, lakes, swamps, and mires. It can also flow, like in rivers and streams, which are called lotic systems. Fresh water can even be hidden underground, moving through rocks in places called aquifers. There's also a special area under big rivers, called the hyporheic zone, that holds a lot of water.