Skip to main content

Maximum Contaminant Levels (MCLs)

In August 2020, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) completed the process of promulgating rules establishing maximum contaminant levels (MCLs) for seven PFAS compounds under the authority of the Safe Drinking Water Act.  The MCLs apply to approximately 2,700 public drinking water supplies in Michigan.

Specific PFAS

Drinking Water MCL
Parts per Trillion (ppt)


  6 ppt


  8 ppt


  400,000 ppt


  16 ppt


  51 ppt


  420 ppt


  370 ppt



An MCL is the maximum amount of a contaminant allowed in drinking water[1].  When the amount of a contaminant in drinking water is higher than the MCL, the water supply must take action as outlined in the Safe Drinking Water Act or its accompanying administrative rules.  Such actions may include public notice, treatment to reduce the level of PFAS contaminants, or additional testing, among others.

Drinking water rules were amended to include the above PFAS MCLs, establishing sampling requirements for these seven PFAS compounds in public water supplies covered under the Michigan Safe Drinking Water Act. Private residential wells are not regulated under the Michigan Safe Drinking Water Act, but Michigan uses the MCLs along with other factors when evaluating private residential well results.

Prior to Michigan establishing PFAS MCLs in August 2020, MPART used the United States Environmental Protection Agency (USEPA) Lifetime Health Advisory (LHA) level of 70 ppt for decision making purposes. The USEPA LHA standard applies to perfluorooctane sulfonate and perfluorooctanoic acid (PFOS and PFOA) combined, or individually if only one is present.  Learn more about USEPA's LHA for PFOA and PFOS.


How the PFAS MCLs were established

In March 2019, EGLE began the process of rule promulgation by submitting a request for rulemaking, citing the need to establish standards for PFAS in public drinking water supplies to protect human health and the environment under the authority of the Safe Drinking Water Act.  In April 2019, the Michigan PFAS Action Response Team (MPART) formed a Science Advisory Workgroup to assist the rulemaking process by preparing a report recommending health-based values for PFAS in drinking water.  The Workgroup was comprised of national experts in toxicology, epidemiology, and remediation of PFAS, assisted by multiple experts within EGLE and the Michigan Department of Health and Human Services. The Workgroup's June 2019 report recommended health-based values (HBVs) for seven (7) PFAS contaminants based on their review and evaluation of PFAS studies nationwide.[2]  HBVs establish a level of contamination below which there is not expected to be adverse health impacts, but HBVs are not on their own enforceable. Using the HBVs recommended by the Workgroup, EGLE proposed amendments to its drinking water rules that established MCLs. 

Following submittal of the rules and supporting documentation to the Michigan Environmental Rules Review Committee (ERRC) in October 2019, and following discussion and public comment, the ERRC in November 2019 unanimously found that the proposed rules satisfied the Administrative Procedures Act and voted to move forward with formal rulemaking.

The official public comment period was open between December 2019 and January 2020.  During this period, written comments were submitted to EGLE. Public hearings took place on January 8, 14, and 16, 2020, during which additional public comments were received in person. In all, over 3,300 written comments were received, logged, and reviewed by EGLE Drinking Water and Environmental Health Division staff.

A summary of public comments was prepared and provided to the ERRC ahead of their February 27, 2020, meeting, along with updated draft rule language.  The ERRC voted to approve the rules as submitted at that meeting. The rules were then provided to the Michigan Office of Administrative Hearings and Rules and prepared prior to submission to the Joint Committee on Administrative Rules (JCAR) in March 2020.  JCAR did not take any action during the fifteen session days that the proposed rule was before it, and the rules became final on August 3, 2020.

Recordings of ERRC meetings and copies of meeting packets can be found on the ERRC webpage. The meeting packet-from the February 27, 2020, meeting includes draft rule language, a summary of the public comments, copies of those comments, transcripts of all three public hearings, and other supporting documents.

Learn more information on this and any additional drinking water rule promulgation efforts by EGLE.