We often hear about groundwater. Does our drinking and cooking water come from groundwater? Is the bath water from our tower from groundwater? We often hear the term groundwater, but what is groundwater actually?

Based on Law Number 7 of 2004, ground water is water found in the rock layers below. Apart from that, there are several definitions from experts including:

• Groundwater is a quantity of water below the earth’s surface which can then be collected by wells, tunnels, or a drainage system with pumping. It can also be called a flow that naturally flows to the ground surface through seepage or a jet (Bouwer, 1978).

• Groundwater is water that is stored in saturated layers until it moves to various soil layers and rocks on the earth until the water comes out as springs, or collects in lakes, ponds, rivers and seas (Fetter, 1994).

• Ground water is water that occupies cavities in geological layers. The soil layer located below the ground surface is also called the saturated zone, with the unsaturated zone located above the saturated zone down to the ground surface, with its cavities containing air and water (Soemarto, 1989).