How Much Water Is There On The Earth?

There is more water on this tiny little planet of ours than we could imagine. If expressed in numbers it would be something like 1,260,000,000,000,000,000,000 liters (1, 260 million trillion liters) of water! It is not only there in the seas and in the rivers, but it also present on the mountain tops and both the north and the south poles, in its solid form. In gaseous state it is all around us, sometimes we call it humidity and at other times, we see it as clouds. In fact there is a cycle – the water cycle – and it works like this: the water evaporates from the oceans, travels through the air; rains back down on to the surface and then returns into the oceans via the rivers.

The oceans are bigger than any thing else we come across in our daily life. About 70 percent of the surface of our planet is covered by them with the average depth of around 1, 000 meters. In fact, 97% of the water of this planet is there in the oceans. The water in the oceans has many salts dissolved in it and the presence of those salts makes the sea-water unfit for drinking. About 2 percent of the water is suitable for drinking, and, of that 2 percent, 80 percent is in the solid form i.e. as glaciers in the poles. Aquifers and wells contain another 0.36 percent of the water and, to our surprise, just 0.036 percent of the planet’s total water supply is found in the lakes and the rivers. But even that miniscule percentage would translate into trillions of liters!

If one is left wondering why these figures don’t add up to hundred percent and where the rest of the water is, then the answer to that question is: the rest of the water is in the atmosphere! We too are around 65 percent water which means if a person weights 70 kg, then 45.5 kg (65%) of that person’s body weight is water. There are also watermelons, milks, juices etc. having a huge amount of water contributing to their body weight.

And water doesn’t like to rest; it moves throughout the year. Beginning its journey from the oceans it first turns itself into clouds, which carry water over land and we get our rains. Rain water flows into the ground, the lakes and the rivers and rivers end up in the oceans and the whole cycle continues. This cycle is known as the ‘water-cycle’.

Each year, around 74 200 km3 (74 200 kilometer cube) of water gets converted into water vapors. The phenomenon is called evaporation. A 1 kilometer cube = 1 billion meter cubes and 1 meter cube = 1 000 liters. According to an estimate about 2 200 km3 of the water that falls down as rain flows into the ground. And at any given time approximately 135, 000 km3 of water can be found in the atmosphere as water vapor, in lakes, as soil moisture, marshes and wetlands, rivers, plants and animals.

Although there is enough water on the planet for everybody, but the irony of fate is: the water is not evenly distributed. Whereas Asia and the South American continents have 30.82 percent and 27.6 percent respectively of world’s fresh water, Australia can boast of just 1.01 percent. Even with in the continents, there is no uniformity. For example; the Yangtze Basin in China stores around 1,000 km3 of water but whole region of Middle East and North Africa does not have more than 145 km3 available for its people.

A possible way to increase water supplies is to purify sea water but it is an expensive and energy consuming process. Experts advise us to use water in a judicious manner; else the availability of fresh water would become so scarce that it could even lead to water wars.

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