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.

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:

The short answer is not very much.  A part per trillion, as it applies to drinking water constituents, is a measure of concentration - how much contaminant there is in a given volume of water.  One ppt means that there is one gallon of contaminant per trillion gallons of water or more specifically 8.34 pounds (weight of 1 gallon of water) of contaminant per trillion gallons of water.  It is an exceptionally small amount and is probably easier to visualize by the following examples.

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Water Department

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Topsfield, MA 01983


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Topsfield, MA 01983


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