Ground Water represents water that is pumped from wells and aquifers.
It is water that has “gone underground”.
If you traveled underground you would eventually get deep enough to find that all the rock around you is soaked with water. This is the saturated zone! The water in the saturated zone is called an aquifer.
Ground Water is water located beneath the ground surface between soil pore spaces and in the layers and fractures of rock formations that can be very far below the surface. A underground unit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table.
The height of water in the saturated zone is called the water table. In dry places, the water table is very deep. But in moist places, the water table is very shallow. When the water table is higher than the actual surface of the ground, there are streams, rivers, and lakes on the land.
The application of solution equilibrium models to ground water quality has had considerable appeal to theoretically minded investigators, although the mineral composition of the solids in such systems commonly is heterogeneous and poorly known. The activities of the solute species can be determined completely and because movement of water through the bedrock is slow, there is a considerable time span available for completion of slow chemical reactions.
Presumably, any solution reaction that reasonably could be expected to reach equilibrium would do so in the usual groundwater aquifer system. However, in ground water systems where geologic strata of high and low permeability are mixed, a flow pattern can occur in which water movement is largely confined to the more permeable layers.
Differences between minerals composition in the geologic layers may cause considerable variation in water quality with depth at any given site. Ground water sampling wells that penetrate several of these layers may yield water that is an enriched mixture of solutes from the more permeable geologic layers.
A sampling well influenced by factors like this is unlikely to give usable ground water quality information. Unfortunately, there is no easy way of evaluating the importance of these effects, nor sometimes of knowing for certain whether these permeable layers are present or absent without extensive study.