The underground region that stores groundwater within pores and fractures is called what?

• A. Potable layer
• B. Aquifer
• C. Reservoir
• D. Capillary fringe

Answer: (B)

Groundwater is stored in a subsurface body of rock or sediment that has interconnected pore spaces and fractures capable of holding and transmitting water. This natural underground storage is called an aquifer. An aquifer can be unconfined, with the water table forming its upper surface, or confined, with a pressure surface. The other terms don’t fit as well: a potables layer isn’t a standard geologic term and relates to water quality rather than a storage medium; the capillary fringe is only a thin zone above the water table where capillary action pulls water into small pores; a reservoir is a more general term and is not the precise underground storage medium defined by interconnected pores and fractures.