What do we call an underground water reservoir that stores groundwater?

An underground water reservoir that stores groundwater is referred to as an aquifer. Aquifers are geological formations that can hold and transmit water, consisting of permeable rock or sediment, which allows water to flow through them. They are essential for supplying water to wells and springs, making them vital to both agricultural and drinking water systems.

The water table represents the upper surface of groundwater, not a reservoir itself. It is the level below which soil and rock are saturated with water. A well is a man-made structure used to access groundwater, but it does not store water. A spring is a natural discharge point where groundwater flows to the surface, but it is not a storage reservoir. Understanding the role of aquifers in the hydrological cycle clarifies their importance in water resource management.