The zone where ground water is found is called the aquifer or it can be the ground water zone depending on what your thinking of.
Groundwater is found in the zone known as the saturated zone, where all spaces between the soil and rock particles are filled with water. This zone lies beneath the water table, which is the top boundary of the saturated zone.
Ground water is located in the zone known as the saturated zone, where all the pore spaces in the rock or sediment are filled with water. This zone exists beneath the water table in an aquifer.
The zone containing well water is known as the saturated zone or the water table. This zone is the region below ground where the spaces between soil and rock particles are filled with water. Wells are typically drilled into this zone to access groundwater for various uses.
The zone of saturation and the water table share two zones of ground water.
ground zone of saturation
Water stops soaking into the ground in the saturated zone because the soil pores are already filled to capacity with water. When saturation occurs, the soil becomes completely saturated, preventing any additional water from infiltrating. This can lead to water pooling on the surface or running off instead of soaking into the ground.
Well groundwater is in the ground so of course it's found in the ground, it can be found truly almost any were in the world. I couldn't tell you exactley were but it's out there, that's for sure.
the hydrosphere
The layer you are referring to is called the saturated zone, or the water table. This is where all the empty spaces in the ground (pore spaces in rocks and soil) are filled with water, creating a zone where the rocks or soil are saturated with water.
It is either the phreatic zone or it could have an aquifer. (=^.^=)
The zone of infiltration is the area in the ground where water seeps into the soil and moves downward due to gravity, while the zone of aeration is the region above the water table where soil pores contain both air and water. The primary difference is that the zone of infiltration involves the actual movement of water into the ground, whereas the zone of aeration refers to the soil layer above the water table where air and water coexist.