Water is the source of life on Earth for all living organisms, as God Almighty says in the Munificent Quran "And, We made from water every living thing." (The Prophets :30). Water is the second most important of all natural resources on Earth next to air as its quantities are fixed, whether it is fresh water, salt water, surface water or underground water.
It covers 80% of the Earth's surface. Oceans and seas contain 317 million cubic miles, glacier ice 7.3 million cubic miles, salt lakes 25,000 cubic miles, rivers 411,000 cubic miles, fresh water lakes 30,000 cubic miles, undergroundwater one million cubic miles, non-saturated soil 16,000 cubic miles, and water vapour 3,100 cubic miles.
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