What is an Unconfined Aquifer?
Unconfined aquifers have a water table at atmospheric pressure and are often recharged from surface water percolation. The level and speed of recharge can differ drastically depending on the geology, surface topography, surface vegetation, precipitation and climate. In general, if natural recharge to the unconfined aquifer equals the pumping withdrawal rate, the system is considered a sustainable source of water. The diagram above illustrates the lack of any overlying impervious layer, or confining layer located between the land surface and the water table, allowing this type of aquifer to interact with surface water.
