What type of aquifer is open to the atmosphere and not restricted by a confining layer?

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An unconfined aquifer is open to the atmosphere and not restricted by a confining layer above it. Because there’s no impermeable cap, the upper boundary of the saturated zone is the water table and it rises or falls with surface recharge from rainfall and infiltration. Wells tapped into this aquifer draw water at the current water-table level, so water levels respond quickly to weather and groundwater recharge. This setup also means the aquifer is more susceptible to surface contamination since it remains directly connected to surface processes.