Water is the most important substance on the earth required by all the living organisms whether human beings, plants or animals. We cannot imagine life on earth without water.
72% of the earth surface is occupied by the water bodies. It approximately 336,000,000,000,000,000,000 gallons which are equal to 326 million trillion gallons of water according to the geological survey of U.S. it is found in solid, liquid and gaseous state. The water from the ocean evaporates and form clouds then it rains down to earth and again flows back to the ocean, seas and rivers. So it always remains in a cycle on the earth.
Oceans are the largest water bodies on the planet to store water. They are many thousands feet deep. Almost all the water on the earth i.e. 98% of it is in the oceans but this water is salty so cannot be used for drinking purposes. Only 2% of the total water present on the earth is fresh out of which 1.6 is trapped in the glaciers and ice caps. Only .36 percent is available in the wells which make thousands of million gallons but it is very small percentage when compared to the total amount of water on the earth. Brazil, Canada, Indonesia, china, Columbia and Russia are the six countries which have 50 percent of the total fresh water. Nearly one-third of the people on the earth live in the areas which do not have enough fresh water reserves.
Remaining water is found in the form of vapors and clouds in the atmosphere or trapped in the animal and plant bodies.
If all the water of the earth is to be stored in one place then it will require a lake which is as large as United States and it must have more than 90 miles of the depth.