Here is an illustration of the fracking process. Notice that the ground water is usually 100’ to 500’ below the surface. The horizontal run is usually 1 or 1.5 miles down. There’s thousands of feet of hard granite that isolates the ground water at 500’. Notice the mile of rock in the illustration between the fracking level and ground water.
Here’s a good 30 second animation without any voiceover:
Here is a good visual and explanation of the above ground portion of fracking: