a well drilled deep enough to reach water that is draining down from higher surrounding ground above the well so that the pressure will force a flow of water upward
See artesian well in American Heritage Dictionary 4
(är-tēˈzhən)
noun
A well drilled through impermeable strata to reach water capable of rising to the surface by internal hydrostatic pressure.
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artesian well
A water table higher than the well ensures water pressure will consistently force water into an artesian well.