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The fresh water takes up 2.5% of the world's water source, of this strictly limited supply, 70% are being permanently frozen under the crust of the Arctic and Anarctic, additionaly, of those snow retention on mountains and glaciers, 87% are difficult to be utilized.
The potable water supply that we(human) can really put in use are portions of rivers, lakes and groundwater, which account for 0.26% of the total water source of the earth.
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