Water that seeps into the ground will travel downward through the soil until either gets trapped or swept away by water flowing horizontally underground.
Water flows at varying speeds underground.
It usually moves slowly and some groundwater does not move at all. Because of the force of gravity, water always moves downslope. Some groundwater reservoirs are like pockets and are trapped by certain types of rocks. Sometimes even the water that is infiltrating into the ground will not be able to reach and refill the pocket of water. These are called confined aquifers .