Water penetrates into the ground, through the soil and underlying rock layers.

This statement is true. Having the right density, water can seep into almost any solid surfaces such as: the ground, through the soil and underlying rock layers. That property is not limited to some types of metals, and vegetations such as tree barks and tree or plant fibers. Water is known as the uniuversal solvent. Being such, if it is being blocked by weaker solid material, water simply passes through it by making the area around it corrode and slowly seep into it and or totally bore a hole onto it for it to flow through like it was never there. This phenomena is characterized by hills which look pretty solid but a body of water often river sliced to it like it was carved there.