PFAS, per- and polyfluoroalkyl substances

PFAS are a broad group of manmade chemicals used for a wide variety of purposes. Used since the 1950s, these compounds are in fire-fighting foams, clothing, flame retardants, food packaging, water proofing materials, and carpeting to name a few. These compounds, of which there are reportedly thousands, are structurally and chemically different from each other but share certain properties such as very strong carbon-fluoride bonds that make them very durable in that they do not readily breakdown in the environment, are not affected by natural biological processes, and can persist for years.

Some of these compounds were first detected in our water during the fall of 2019. Further tests conducted in 2020 have confirmed the presence of these chemicals in varying amounts. We now test for 18 of these compounds on a monthly basis. For detailed testing results please visit our water quality site at

MassDEP promulgated new regulations concerning PFAS which took effect in October 2020. 

This has been a moving target but has decreased over the last several years.  The first testing for PFAs was done by the USEPA as part of their Unregulated Contaminant Monitoring Rule #3 (UCMR3).  From 2013-2015, they tested a cross section of public water supplies accross the country to see how common PFAS is in drinking water.  Topsfield was selected to participate in the study and both of our sources were tested twice during 2014.  No PFAS compounds were detected.

As a result of the UCMR3 tests and emerging scientific evidence, USEPA created a health advisory in 2016 for two chemicals - PFOA & PFOS.  The combined total of these compounds shouldn't exceed 70 parts per trillion (ppt).  MassDEP announced in January 2019 that they intended to regulate PFAS and published draft regualtions in October of 2019.  The proposed regulations went through a typical review process and public comment period and went into effect on October 1, 2020.  EPA has lowered allowable levels for certian PFAS compounds with new national regulations published on April 10, 2024.

The United States Environmental Protection Agency (EPA) issued the final PFAS regulations on April 10, 2024.  The regulations were initally issued in draft form during 2023.

EPA Regulations

The new EPA regulations set Maximum Contaminant Levels (MCLs) for PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid) at 4 parts per trillion (ppt); PFNA (perfluorononanoic acid), PFHxS (perfluorohexanesulfonic acid), and GenX (hexafluoroproplene oxide) at 10 ppt; and a hazard index for mixtures of PFNA, PFHxS, GenX and PFBS.

The new regulations are being phased into effect.  Systems are required to start testing for these compounds within 3 years, report the results in the annual Water Quality Report, and notify customers of any violations.  Systems have 5 years to comply with the new MCLs by either installing appropriate treatment or finding alternative PFAS-free water supplies.

The regulations also created Maximum Contaminant Level Goals (MCLGs) for PFOS and PFOA of 0 ppt.  This means that EPA would like to eliminate PFOS and PFOA from water supplies accross the country but current testing protocols, treatment methods, and economic conditions make it infeasible.  We expect the MCLs to drop as testing and treatment methods improve.

Our water was first tested for PFAS in 2014 as part of US EPA's Unregulated Contaminant Monitoring Rule Part 3.  This program tested a cross section of water supplies across the country for a variety of contaminants to determine the frequency of occurence and the amounts found.  Six PFAS compounds were included in the tests.  The table below shows the minimum reportable level for each compound for the UCRM3 tests and current methods.  The minimum reportable level is the lowest level of the contaminant that can be reliably measured.  Results found below this level are listed as 'non-detectable'.

 Compound  UCMR3 MRL (2014)   Today's MRL (2020)   Average Level Found Today (2019-2020)
PFOS 40 ng/L 1.8 ng/L 7.2 ng/L
PFOA  20 ng/L  1.8 ng/L 12.6 ng/L
PFNA  20 ng/L 1.8 ng/L 0.4 ng/L
PFHxS 30 ng/L 1.8 ng/L 0.8 ng/L
PFHpA 10 ng/L 1.8 ng/L 1.9 ng/L
PFBS 90 ng/L 1.8 ng/L 2.1 ng/L


The tests conducted today are approximately 10 times more sensitive than the tests done in 2014.  

Our greensand water treatment facility went online in March 2019. Unfortunately, it is not equipped to remove PFAS and the oxidants (sodium hypochlorite & potassium permangante) used to remove manganese from our source water are not compatible with PFAS removal systems. So, where does that leave us?

The good news is manganese needs to be removed from the water before removing PFAS so our treatment plant would need to be modified not replaced. If PFAS treatment is needed, these will likely be the steps:

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