All the water underground, on the surface, and in the atmosphere amounts to about 332 million cubic miles. That makes a cube with a side of 693 miles, whose base stretches from Indianapolis to Denver. You couldn't even fill the Pacific with the water in that cube, let alone everything else.
So, the big takeaway here is that the Earth’s oceans are nothing more than a thin film on the surface of the Earth, relatively speaking.
And how big would a cube of just the fresh water be? It would have sides 202 miles long and sit nicely on top of Iowa.
And the drinkable water cube? Its sides would be 29 miles long and it would fit into Rhode Island.