Quick Answer
Risks of over-pumping a deep well include lowering water levels, collapsing the well casing, and reducing the well's yield over time. This can lead to costly repairs or even render the well unusable. In extreme cases, over-pumping can also cause nearby water sources to become contaminated.
Well Collapse and Casing Damage
Over-pumping a deep well can cause the surrounding rock or soil to collapse, leading to damage to the well casing or screen. This can result in costly repairs, including the need to re-drill the well or replace the casing. A well casing collapse can also release contaminated soil or rocks into the well, rendering it unusable.
Yield Reduction and Decreased Water Level
Repeatedly pumping a deep well beyond its sustainable yield can cause the water level to drop significantly. This can lead to increased energy costs to pump water from greater depths. In some cases, the well may require more frequent maintenance or repairs to maintain its original yield.
Groundwater Contamination and Subsidence
Over-pumping a deep well can also cause nearby water sources to become contaminated with sediment, chemicals, or other pollutants. Additionally, excessive water removal can cause the ground surface to sink, leading to structural damage to buildings and roadways. This phenomenon is known as subsidence. A common example of this is the sinking of the city of Houston, Texas, due to over-pumping of the Ogallala Aquifer.
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