Statewide Testing Initiative

If you receive a water bill, your water
comes from a public water supply. 
If you do not pay for your water, you
are on a private well. Approximately
75% of Michigan residents get water
from a public water supply.
Approximately 25% are on private

Public water supplies may be large, like the Great Lakes Water Authority, which serves 3.7 million residents, or they may be smaller, such as a supply serving a manufactured housing community.  Some public water supplies get water from groundwater, some from surface waters (lakes or rivers) and some blend groundwater and surface water sources together. To ensure the drinking water for the largest portion of Michigan residents was tested for PFAS, beginning in April 2018, the Michigan Department of Environmental Quality (MDEQ) implemented a statewide program to test:

  • 1,110 Public Water Supplies
  • 461 Schools on their own wells
  • 150 Daycares and Head Starts
  • 17 Tribal water systems

This sampling was completed in December 2018. Therefore, approximately 7.7 million of Michigan's 10 million residents have now had their drinking water tested for PFAS. The results of this testing are detailed in the interactive tables below. A summary report of the overall results is available to the right.  


View details on test methods used (pdf).

The MDEQ has provided recommendations based on PFAS levels. View this notification protocol (pdf). 

The United States Environmental Protection Agency (USEPA) set a Lifetime Health Advisory (LHA) level for two PFAS in drinking water: perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) . The LHA level is 70 parts per trillion (ppt, equal to 70 ng/L) for PFOA and PFOS combined, or individually if only levels for other PFAS chemicals. The State of Michigan is using 70 ppt for decision making purposes.

Only two supplies were found to have PFOS+PFOA over the USEPA LHA:

What’s next?

  • In March 2019, the MDEQ began quarterly sampling of Public Water Supplies sampled last year with results greater than 10 ppt but less than 70 ppt PFOS+PFOA or Total Tested PFAS of more than 10 ppt.  This sampling will be done for one year and will help determine if these 62 supplies change over time and help prioritize and direct next steps. View the map of the 2019 quarterly sampling (pdf).
  • As of early April 2019, the MDEQ was developing a plan to conduct more statewide sampling of public water supplies not previously tested.  Look here for updates on those plans.

Statewide Sampling Initiative Testing Results for Public Water Supplies
Public Water Supplies screen shot

Statewide Sampling Initiative Testing Results for Schools, Child Care Providers, and Michigan Head Start Programs
Schools on Their Own Well dataset screen shot

Public Water Supply Testing Results Prior to Statewide Sampling Initiative
Public Water Supply Testing Results screenshot