What is the primary source of groundwater?

The primary source of groundwater is precipitation. When it rains or snows, a portion of this water infiltrates the ground, moving through the soil and rock layers until it reaches the saturated zone, where it fills the pore spaces within the underground materials. This process is known as recharge, and it is essential for maintaining groundwater supplies. Over time, precipitation is the primary means through which water enters aquifers, which are underground layers of water-bearing rock or sediment.

Other options like lakes, rivers, and glaciers do contribute to surface water and can have indirect effects on groundwater recharge, but they do not serve as the primary source of groundwater. Lakes and rivers primarily hold surface water, and while they can provide some amount of infiltration, they are not the main means through which groundwater is replenished. Glaciers primarily store water in solid form; while they can release water during melting, again, the direct role of groundwater formation is fundamentally tied to precipitation.