Groundwater

Groundwater is freshwater that is stored beneath the Earth’s surface in soil and rock.

When it rains, some water flows over the land, but much of it seeps into the ground.

This water moves through spaces, or pores, between particles in soil and rock.

Rocks that allow water to pass through easily are called permeable rocks, similar to how a sponge lets water flow through it.

Water keeps moving down through these layers until it reaches a rock that blocks its path. This is called an impermeable rock.

The water builds up above this layer, filling all the tiny spaces in the rock. This area is called the saturated zone.

The water table is at the very top of this saturated zone. It can rise after heavy rain and drop during dry weather.

Above the water table is the unsaturated zone, where rock and soil are not fully filled with water.

If the saturated rock holds a lot of water, it’s called an aquifer. An aquifer is like an underground water storage tank.