Statewide Testing Initiative

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 Environment, Great Lakes, and Energy (EGLE) implemented a statewide program to test Michigan's public water supplies across several phases of sampling.

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 three supplies have been found to have PFOS+PFOA over the USEPA LHA:

What’s next?

  • In March 2019, EGLE 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, EGLE was developing a plan to conduct more statewide sampling of public water supplies not previously tested, as well as additional quarterly and monthly monitoring. Details on Phase II and additional monitoring are available from the links below.