Well Water Contamination


There are multiple ways that well water contamination can happen. Heavy rainfall, spring runoff, or flood events can overwhelm even well-constructed, recently drilled wells, and can introduce surface contaminant into the aquifer below.

Well water contamination sources

Potential Well Water Contamination Sources

If your well is older, there are even more potential avenues for surface contamination to enter your drinking water.

Some of these issues could be:

water well diagram

Diagram of the important parts of a water well

  • A dug well lined with poorly sealed brick, stone, or tile, or having unsealed covers.
  • An improperly sealed casing through a bedrock formation or other unconsolidated formation, This can allow the migration of contaminated water into the aquifer.
  • If the well casing does not extend far enough above the ground surface, surface water can enter the top of the well casing.
  • If a well casing ends in a basement, pit, or other area prone to flooding or seepage.
  • Corrosion can deteriorate old well casings and allow water to seep into the well from holes or cracks.
  • Contaminated near-surface water can enter a well if the well casing is at a non-complying depth.
  • Old stove-pipe casings are now considered sub-standard, as they can allow near-surface water to infiltrate the well.
  • The well cap could be poorly installed, allowing insects and small animals to enter the well.
  • The source of the contamination is too close to the well (such as septic), and the casing does not extend deep enough to assure bacteria have been filtered out of the water that recharges the aquifer.

If you suspect any of these issues with your well, you are best to call in professional help. Get in touch with your local well drilling professional.

To learn more about how to take care of your well, and how to identify potential issues, the National Ground Water Association has a fantastic resource, wellowner.org.  This website covers all the basic information pertaining to well ownership and stewardship, and runs regular training classes about well care.