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EPA Announces PFAs Limits for Drinking Water

Archived News Release: April 12, 2024 - On April 10, 2024, the Environmental Protection Agency (EPA) announced the final National Primary Drinking Water Regulation (NPDWR) establishing legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water.

“Ann Arbor Water is glad the EPA took action to develop national PFAS drinking water standards to protect Americans from these forever chemicals," said City of Ann Arbor Public Service Area Administrator Brian Steglitz. “Proactive investment in treatment technologies by Ann Arbor Water has positioned us to immediately be compliant with these new standards ensuring our customers continue to have access to safe and reliable drinking water. The investments that we have made and strategies that we use for PFAS removal at the Water Treatment Plant allow us to meet these new rules immediately, ahead of the five-year compliance window."

CompoundFinal MCLGFinal MCL (enforceable levels)Ann Arbor Water
PFOAZero4.0 parts per trillion (ppt) (also expressed as ng/L)Non-detect
PFOSZero4.0 pptNon-detect
PFHxS10 ppt10 pptNon-detect
PFNA10 ppt10 pptNon-detect
HFPO-DA (commonly known as GenX Chemicals)10 ppt10 pptNon-detect
Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS

1 (unitless)

Hazard Index

1 (unitless)

Hazard Index



According to the EPA news release, it expects that over many years the final rule will prevent PFAS exposure in drinking water for approximately 100 million people, prevent thousands of deaths, and reduce tens of thousands of serious PFAS-attributable illnesses. The new EPA limits are lower than the standards that were implemented by the State Michigan in 2020 and take precedence.

The final EPA rule requires:

  1. Public water systems must monitor for these PFAS and have three years to complete initial monitoring (by 2027), followed by ongoing compliance monitoring. Water systems must also provide the public with information on the levels of these PFAS in their drinking water beginning in 2027. Ann Arbor Water already provides information about the levels of PFAS in our source and finished drinking water. You can find current and historical results at
  2. Public water systems have five years (by 2029) to implement solutions that reduce these PFAS if monitoring shows that drinking water levels exceed these MCLs. Ann Arbor Water already treats for PFAS and will continue to monitor to ensure compliance with the MCL.
  3. Beginning in five years (2029), public water systems that have PFAS in drinking water which violates one or more of these MCLs must take action to reduce levels of these PFAS in their drinking water and must provide notification to the public of the violation. 

Ann Arbor has 123,851 residents, spans 28.97 square miles and is frequently recognized as a foremost place to live, learn, work, thrive and visit. To keep up with City of Ann Arbor information, subscribe for email updates, and follow the city on Twitter and Facebook. The city's mission is to deliver exceptional services that sustain and enhance a vibrant, safe and diverse community.