You know that on the globe of the sea, rivers, lakes depicted in blue. If you look closely, you can see that the blue paint on the globe in 2 times more than any other. This means that the seas and oceans occupy on the Earth's surface is 2 times more space than land. If all the water from rivers, seas, oceans and lakes spread across the planet, the Earth would be under the penalty of a layer of water.
97,75 % of the total world stock of water is salt water of oceans and seas, of 2.25% is fresh. But almost half of this amount of water a person can not use, as it is in the form of ice and snow caps in Antarctica, the Arctic, Greenland, on the tops of mountains in various parts of the Earth. Actually fresh water that can eat people, very little.