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 has a diameter of about about 1,385 kilometres. 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).
Via Seth Dixon