Not such a wet planet: Picture shows how all the water on Earth would fit into one 860-mile-wide ball

By Rob Waugh

Published: 11:08 EDT, 8 May 2012 | Updated: 03:11 EDT, 9 May 2012

When people talk about our water supply running out, it's often difficult to imagine - but according to the U.S. government's Geological Survey, all the water on Earth would fit into an 860-mile-wide bubble.

Around 70% of Earth's surface IS water-covered - but it's a very, very thin layer.

Although 70% of Earth's surface is water-covered, it's a very, very thin layer

Every sea, river and underground lake would fit into what looks like a tiny blue 'blister' on the side of our planet.

'As you know, the Earth is a watery place - but all the water on, in, and above the Earth would fill a ball the size of that tiny blue sphere sitting on the United States, reaching from about Salt Lake City, Utah to Topeka, Kansas,' says a USGS release.

The oceans hold about 96.5 percent of all Earth's water.

Water also exists on Earth in the air as clouds and water vapour, in lakes and rivers, in icecaps and glaciers, and in living creatures - but all of that would fit into the tiny ball.

'The vast majority of water on the Earth's surface, over 96 percent, is saline water in the oceans,' says the USGS.

'But it is the freshwater resources, such as the water in streams, rivers, lakes, and groundwater that provide people (and all life) with most of the water they need everyday to live. Water sitting on the surface of the Earth is easy to visualize, and your view of the water cycle might be that rainfall fills up the rivers and lakes.

'But, the unseen water below our feet is critically important to life, also. How would you account for the flow in rivers after weeks without rain? In fact, how would you account for the water flowing down this driveway on a day when it didn't rain? The answer is that there is more to our water supply than just surface water, there is also plenty of water beneath our feet.'