We often hear people say 70% of the Earth's surface is covered by water. Oceans and seas constitute the largest amount of water, roughly 96.5%. The rest exists in lakes, rivers, underground water sources, in our body, and in your pet.
That does sound a lot isn't it? In reality, it's really not that much.
Let's start with the smallest blob, the one hanging above the state of Georgia. It represents the surface-fresh water sources in all the lakes and rivers on the planet, i.e. the water that we use everyday. The diameter of this sphere is about 56.2km, and the volume of this sphere is about 93,113 km3.
The intermediate sphere, above Kentucky, shows the Earth's liquid fresh water in groundwater, swamp water, rivers, and lakes. We get our fresh water from rivers and lakes, but underground water sources are most of the time unavailable. This sphere has a 272.8 km diameter, and a volume of 10,633,450 km3.
The largest blue sphere represents all the water on Earth-seas, oceans, lakes, rivers, underground water. That sphere has a radius of 1385 km, and the volume would be 1.386 billion km3.
But to think on the positive side, it's amazing so many water-carrying asteroids actually hit the Earth during its infancy to result in that much water on Earth today.