Much of the world’s freshwater lies out of sight. Groundwater is water that occupies the pore spaces and fractures beneath the land surface. It moves slowly through aquifers under the influence of gravity and pressure gradients.

Recharge occurs where precipitation infiltrates; discharge occurs at springs, streams, and wells. The water table marks the top of the saturated zone in unconfined systems. Groundwater quality depends on the minerals it dissolves and any contaminants introduced from the surface.

Many communities rely entirely on groundwater for drinking and irrigation. Over-extraction can lower water levels, dry up springs, and cause subsidence. Protecting recharge areas and monitoring withdrawals are essential for sustainable use. The hidden nature of groundwater makes careful scientific management especially important.

• Water beneath the land surface in pores and fractures
• Moves slowly through aquifers
• Critical source of freshwater
• Vulnerable to overuse and contamination