If All of Earth's Water was put into Single Sphere, from the USGS Water Science School...
"This picture shows the size of a sphere that would contain all of Earth's water in comparison to the size of the Earth. The blue sphere sitting on the United States, reaching from about Salt Lake City, Utah to Topeka, Kansas, has a diameter of about 860 miles (about 1,385 kilometers) , with a volume of about 332,500,000 cubic miles (1,386,000,000 cubic kilometers). The sphere includes all the water in the oceans, seas, ice caps, lakes and rivers as well as groundwater, atmospheric water, and even the water in you, your dog, and your tomato plant."
The sphere does not include the potential water that some scientists believe may be trapped in the mantle (and thus not accessible on the surface). For more about water that is not on or near the surface, see: http://news.nationalgeographic.com/news/2002/03/0307_0307_waterworld.html
Via Seth Dixon