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Why is only a small share of Earth’s freshwater found in lakes and rivers?

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water rapids, Niagara Falls, Canada — water Water is the most plentiful compound on Earth and is essential to life. Although water molecules are simple in structure (H₂O), the physical and chemical properties of water are extraordinarily complicated.

Only a small share of Earth’s freshwater is found in lakes and rivers because the vast majority of the planet's freshwater is stored elsewhere, primarily in glaciers and ice sheets, as well as in groundwater reservoirs.12

Specifically, glacier ice accounts for approximately three-fourths of all the world's freshwater. Most of the remaining continental freshwater is held in groundwater, which occupies the void spaces in soils and geologic strata. In contrast, lakes and rivers represent only a tiny fraction of total global water; freshwater lakes constitute less than 0.4 percent of all continental freshwater, and rivers hold an even smaller volume.34521

While these surface water bodies are vital for human use and play a significant role in the water cycle, they are quantitatively minor compared to the massive volumes of water locked away in ice and subsurface aquifers.152