Groundwater supplies are recharged by precipitation or from rivers and lakes. Groundwater removed by wells or discharged by springs may have been stored for thousands of years, or may have entered the aquifer quite recently. Wells are drilled into a variety of different aquifer formations to supply water for many different uses. Specialized equipment is required to meet the construction standards for drilling a well, installing the well casing and screen, back filling the well hole, and test pumping the well for its intended purpose. Without proper well drilling and construction techniques, the reliability of the well and protection provided to the aquifer may be questionable.
Water is removed from an aquifer using pumps.
Pumps use mechanical energy supplied by a drive motor or engine to force water toward the land surface. Removing water lowers the water level in the well. Since the water level always is lowest in the well, water from the surrounding aquifer flows toward the well to replace the water being removed. Water level changes associated with groundwater pumping. When pumping starts in an unconfined aquifer, most of the water is removed from very near the well.