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What can cause water levels in wells to change?

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Welcome to CoreFacts, where we're always short on time and big on science. I'm Danielle Eganhouse. Today's question is about well water.

What can cause water levels in wells to change?

Water levels in wells are constantly changing both in the short term and over the long term. Some wells even have a seasonal change. In the short term, water levels can be lowered just by pumping water out of the well for use. Also, a well may be pumped so much as to cause the water level in nearby wells to be lowered, too. It all depends on how fast the aquifer that the well uses is resaturated with water from the surface or from the area surrounding it. In some places people have withdrawn water faster than water replenishes the aquifer, and the wells have stopped producing water.

Sometimes this is a long-term problem occurring over a very large area. If it takes a long time to replenish the aquifer a field of wells may stop producing. Users will have to wait until the aquifer becomes more saturated again before turning the pumps back on. Also, an aquifer can only contain water if there is water coming into it, usually from rainwater seeping down from the surface. In a severe drought water levels in wells can significantly decline.

And now you know. Join us again every weekday for a new CoreFact. For other CoreFacts, or for CoreCast, our in-depth science podcast, go to If you'd like to have a question featured on our show, give us an email at or a phone call at 703-648-5600. Remember, long distance fees do apply.

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