News | October 19, 2017

New National Study Identifies Well Owners Potentially At Risk Of Arsenic Exposure

A new national study estimating 2.1 million Americans on household water wells may be at risk of harmful exposure to arsenic underscores the importance of well owners testing their water for contaminants of local concern, the National Ground Water Association said recently.

“Our standard advice to private well owners is to test water for anything of local concern,” said Cliff Treyens, NGWA’s director of public outreach. “Contamination threats can vary from locale to locale with some caused by human activity and others such as arsenic occurring naturally in the environment.

“A good place to check on local groundwater contamination threats is the county health department,” Treyens said. Well owners can look up their county health department on NGWA’s website,

The study by the U.S. Geological Survey and the CDC’s National Center for Environmental Health shows areas potentially affected by arsenic levels greater than 10 parts per billion — the federally established “maximum contaminant level” at which regulated public water systems are required to take corrective action. Private well water quality, however, is not regulated by the government on an ongoing basis. Private well owners are responsible for testing their water and taking action to keep it safe.

The study’s top 10 states for people at risk for harmful arsenic exposure based on the size of the at-risk population are:

  1. Michigan, 192,747
  2. Ohio, 189,191
  3. Indiana, 150,858
  4. North Carolina, 119,633
  5. California, 115,823
  6. Maine, 102,452
  7. Texas, 95,455
  8. Pennsylvania, 80,729
  9. Minnesota, 80,353
  10. Wisconsin, 72,670.

Significantly, the study may shed new light on areas not known to have arsenic issues in the groundwater.

“We identify areas of high and low potential exposure in areas of limited arsenic data. These areas may be viewed as potential areas to investigate further or to compare to more detailed local information,” the study states.

To help well owners address the issue of arsenic in well water, NGWA has developed educational tools on testing water and treatment if necessary. These tools, available on, include:

For more information, visit

About The National Ground Water Association

The National Ground Water Association is a not-for-profit professional society and trade association for the global groundwater industry. Our members around the world include leading public and private sector groundwater scientists, engineers, water well system professionals, manufacturers, and suppliers of groundwater-related products and services. The Association’s vision is to be the leading groundwater association advocating for responsible development, management, and use of water.

SOURCE: The National Ground Water Association