In simple terms, freshwater is water that has little or no dissolved salts and dissolved solids. It excludes sea or marine waters and brackish water. All over the world, water comes in other forms such as ice-sheets, glaciers, lakes, ponds, rivers, streams, and icebergs. The quantities found in every geographic area may vary.

Freshwater may be still or fast flowing. Stillwater (static or non-flowing) freshwater is known as Lentic systems whiles flowing freshwater is known as Lotic Systems. Others come from underground as groundwater in aquifers and underground streams.

Where does all freshwater come from?

Freshwater comes from precipitation from the atmosphere, usually in the form of rain, mist, and snow. When rain and snowfall happens, they find their way into streams and rivers which run down from mountain tops to low-lying areas. Eventually, they end up in the sea or ocean. Because much of atmospheric water end up falling into our water bodies, we must keep an eye on the chemicals that find their way into the atmosphere via air pollution. 

But how does the water end up in the atmosphere in the first place? That can be explained by a model called The Water Cycle.