The precipitation from the sky and the infiltration from river runoffs on the ground surface are the major sources of groundwater. More accurately, due to the continuous hydrological cycle in nature, water evaporates from the surface of the earth due to heat from the sun, rises into the atmosphere, cools and condenses into rain or hail, falls again to the surface as precipitation, and rises up again with heat. The sun’s heat endlessly provides energy, so the water cycle continues as a result. The water stored in the ground due to infiltration and gravity is the source of groundwater.