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Why is most of Earth’s water unavailable for direct human use?
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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.
Most of Earth’s water is unavailable for direct human use primarily because it is either too salty or inaccessible. Approximately 97 percent of all water on the planet is ocean water, which contains high concentrations of dissolved salts and minerals that make it unfit for drinking, irrigation, or most industrial applications.123
Of the remaining small percentage of fresh water, the vast majority is not readily available for consumption:
- Frozen Water: A significant portion of fresh water is locked away in glaciers, polar ice caps, and permafrost.123
- Inaccessibility: Much of the remaining fresh water exists as groundwater, which may be located too deep underground to be economically or technically accessible.14
- Distribution and Quality: Even where fresh water exists in lakes, rivers, or accessible aquifers, it is not uniformly distributed across the globe. Furthermore, human activities such as industrial growth, urban development, and pollution often render otherwise usable water sources unsafe or unfit for consumption.23
While technologies like desalination can convert salt water into fresh water, these processes are currently expensive and energy-intensive.5