Concerns of citizens and state and national regulators have placed per- and polyfluoroalkyl substances (PFAS) compounds such as PFOS and PFOA in the national news. 

On March 14, 2023, EPA proposed maximum contaminant limits for compounds listed below. MAWC is under the limit for all these compounds, based on samples analyzed in the past six months. 

The hazard index for the last four compounds is calculated using the formula below. All MAWC samples are below these limits.

View the MAWC results here: 

Visit EPA's webpage on PFAS for more:

In June 2022, the U.S. EPA announces new PFAS health advisories

The U.S. Environmental Protection Agency (EPA) released new and revised drinking water lifetime health advisories (HAs) for four PFAS. Lifetime HAs are intended, with a margin of safety, to represent levels at which adverse health effects are not expected to occur over a lifetime of exposure. The values are: 

Final Lifetime Health Advisories 
Hexafluoropropylene oxide dimer acid (GenX) - 10 ng/L 
Perfluorobutanesulfonic acid (PFBS) - 2,000 ng/L

Interim Lifetime Health Advisories 
Perfluorooctanoic acid            (PFOA) - 0.004 ng/L 
Perfluorooctanesulfonic acid (PFOS) - 0.020 ng/L

The interim lifetime PFOA and PFOS HAs replace the previous 70 ng/L combined advisory value released in 2016. Approved analytical methods for PFOA and PFOS have minimum reporting levels (MRLs) of 4 ng/L. EPA recommendations accompanying the interim advisories recommended further investigation, public communication and evaluation of exposure reduction when PFOA and PFOS levels exceed the MRLs.

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During a fire in McKeesport on July 16, 2021, legacy class-B foam was introduced into the drinking water system in the Lower 10th Ward. While several rounds of testing and flushing resolved the issue to the satisfaction of the Department of Environmental Protection, the test results are posted here:


According to the EPA, per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that includes PFOA, PFOS, GenX, and many other chemicals. PFAS have been manufactured and used in a variety of industries around the globe, including in the United States since the 1940s. PFOA and PFOS have been the most extensively produced and studied of these chemicals.

Areas with Defense Department bases, where the substances were used in firefighting foam, and waterproofing and tanneries were sometimes users of the chemicals.


EPA: Basic Information on PFAS 

EPA: Meaningful and Achievable Steps You Can Take to Reduce Your Risk

DEP: PFAS in Pennsylvania