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 survey to test Michigan's public water supplies across several phases of sampling.
Prior to the beginning of this statewide survey, 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. In the absence of a promulgated drinking water PFAS standard(s) at the time, the State of Michigan used 70 ppt for decision making purposes during the statewide survey.
If you receive a water bill, your water comes from a public water supply. If you do not pay for your water, you are likely on a private well. Approximately 75% of Michigan residents get water from a public water supply. Approximately 25% are on private wells.
During the statewide survey, only three supplies were found to have PFOS+PFOA over the USEPA LHA. Details on the response actions related to these three can be found here:
*Results are provided in parts per trillion. A part per trillion (ppt) is the equivalent of 1 drop of water in 20 Olympic-size swimming pools
Definitions of the information provided in the sampling results tables:
These analytical results include detections for 14 – 28 PFAS analytes, depending on the analytical method used. Each result has a "flags" column that corresponds to important data qualifiers.
Understanding the flags: Contaminant data often include flags, also known as qualifiers, which are notes attached to data that gives detailed information about that particular result. In the drinking water PFAS data layer, PFAS analytes associated with a “U” flag were not detected in the sample and therefore a null value is displayed. “J” flagged results indicate an estimated concentration as the result is above the minimum detection limit (MDL) but below the laboratory reporting limit. “J-“ flagged results indicates an estimated concentration as the result is above the minimum MDL, below the laboratory reporting limit, but biased low. “UJ” flagged results indicates a not detected at the value estimated reporting limit. “R” flagged results indicate a rejected sample as serious quality control issues render the result value bot usable. “*” flagged results indicates that the result values have not been verified.
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PFAS has been found in municipal water samples from Grayling Municipal Wells in Crawford County.
PFAS has been found in municipal water samples from the Plainfield Township's Municipal Water System in Kent County.
PFAS has been found in municipal water samples near the Tawas' Huron Shores Regional Water Authority in Iosco County.
PFAS has been found in drinking water samples near the Ann Arbor Municipal Water Treatment Plant in Washtenaw County.
