What is fresh water?
Fresh water is low-salt water we can drink or use to irrigate crops. It comes from rivers, lakes, or underground aquifers, and ultimately from rain or snowmelt.
Technically, fresh water has 1,000 parts per million or less (0.1% or less) of dissolved salts such as chlorine, sodium, and magnesium. For comparison, ocean water is about 3.5% salt. In more familiar terms, freshwater used for drinking has less than about a quarter teaspoon of salt per gallon.
Fresh water is a limited, valuable, renewable resource. Only 3% of water on Earth is fresh. Of that small percentage, two-thirds or more is frozen and in the form of glaciers or polar ice caps.