This is called the saturation zone.

This process involves the addition of microorganisms, nutrients and an electron acceptor into the saturation zone of a contaminated aquifer.

Groundwater is all water below the surface of the ground in the saturation zone, ie below the water table such as in aquifers, wells and boreholes.

This infiltrating water continues its downward journey to the zone of saturation to become a part of the groundwater in aquifers.

At increasing depths water fills in more of the pore spaces in the soils, until the zone of saturation is reached.

The phreatic zone, or zone of saturation, is the area in an aquifer, below the water table, in which relatively all pores and fractures are saturated with water.

A phreatophyte is a deep-rooted plant that obtains a significant portion of the water that it needs from the phreatic zone (zone of saturation) or the capillary fringe above the phreatic zone.

Theories in the creation of karst topography and karst fensters involve vadose water above the water table and deep circulating phreatic water (water in the zone of saturation) eroding away subsurface rock.