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What makes a groundwater well go dry?

A well is said to have gone dry when water levels drop below a pump intake. This does not mean that a dry well will never have water in it again, as the water level may come back through time as aquifer recharge from precipitation seepage increases and/or pumping of the aquifer is lessened. It is true that all the water in the ground comes from infiltration of precipitation from above, but the geology of the underground rock determines the infiltration and movement characteristics of the water that is in the ground.

The water level in a well depends on a number of things:

  • Depth of the well
  • Type (confined or unconfined) of aquifer the well taps
  • Amount and rate of pumping that occurs in the aquifer
  • Permeability and porosity of the underground rock
  • Amount of recharge occurring from precipitation or artificial recharge

Wells in unconfined water table aquifers are more directly influenced by the lack of rain than those in deeper confined aquifers. A deep well in a confined aquifer in an area with minimal pumping is less likely to go dry than a shallow, water-table well.

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