Well Water Contamination

Well Water Quality

If you’re using a private well or one shared with a few neighbors, you’re responsible for the quality of the water you and your family are consuming. Understanding how your well water may become contaminated with natural or man-made contaminants is key to avoiding possible illness and managing aesthetic water issues.

There are multiple ways that well water contamination can happen like: heavy rainfall, spring runoff, and flood events can overwhelm even well-constructed, recently drilled wells and can introduce surface contaminants into the aquifer below. If your well is older, the risk of surface contamination infiltrating your well is even greater.

Sources of well water contamination

Potential Well Water Contamination Issues

  • Sources of contamination, like a septic system, are too close to the 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, which 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 another 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.

Possible Microbes in Your Well Water

The most important thing to know about microbes in your well water is that you cannot see, smell, or taste them. The only way to know if you’re drinking water presents a risk is to conduct a bacterial test with a certified laboratory. 

According to the CDC, the top causes of disease outbreaks in wells are:

  1. Hepatitis A (virus)
  2. Giardia (protozoa)
  3. Campylobacter (bacteria)
  4. Shigella (bacteria)
  5. E. coli (bacterium)
  6. Cryptosporidium (protozoa), Salmonella (bacteria) tie

More than 20 percent of private domestic wells sampled nationwide contain at least one contaminant at levels of potential health concern, according to a study by the U.S. Geological Survey (USGS).  Bacteria, including total coliform bacteria and Escherichia coli, were found in as many as one third of a subset of 400 wells.   – United States Geological Survey

Further Help and Resources

If you suspect any of these issues with your well, it is 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.