A well reduces the water table in the immediate area under the well head in an inverted cone shape called the “cone of depression.” This creates a dewatered area around the well. Although different soil compositions shrink at different rates when dewatered, they all shrink.

    When a well is drilled close to a house, like in the photo at the top of this page, the cone of depression extends under the foundation and can be a contributing factor to foundation settlement. The size of the cone and the rate at which it extends across the top depend on the rate of pumping and transmission properties of the aquifer below it. Other factors, such as site drainage and concentrated loads along the exterior walls, can also affect foundation movement. At the corner of the house shown above with the well just a few feet away, there were stairstep settlement cracks in the concrete block wall that had been patched and since reopened again.

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Here’s links to a collection of our other blog posts about WELLS:

• What is the blue dumbbell-shaped tank at the well equipment?

• What is the tank marked "potassium permanganate" in the water treatment system for? 

• Does an abandoned well need to be capped or removed?

• Does a homeowner need a permit to drill a water well on their property in Florida? 

• Is a high iron level in well water a health hazard?

• How often should a well be disinfected? 

• Should I test my well water for arsenic?

• What is the danger of radon in well water? 

• What size generator do I need to run my submersible well pump?

• Why would a well need to have a chlorinator/dechlorinator system? 

• Why does my well pump turn on and off every time I use water?

• What is the required water testing for an FHA, VA, or USDA mortgage application? 

     Visit our WELLS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles. 

Diagram - USGS, public domain