PFAS Information


On September 24, 2020, the Massachusetts Department of Environmental Protection (MassDEP) announced the final regulations for PFAS in drinking water and continue to clarify how laboratory results should be calculated and reported. The MassDEP press release can be found here. In October 2020, MassDEP promulgated a new drinking water standard for the sum of six PFAS compounds (PFAS6, see table below). This new standard requires all Massachusetts public water suppliers test for PFAS. The Maximum Contaminant Level (MCL) for the sum of PFAS6 may not exceed 20 nanograms per liter (ng/L), also equal to 20 parts per trillion (ppt). Federal Drinking water standards do not currently regulate PFAS.

PFAS6 Compounds

AbbreviationChemical Name
PFOSPerfluorooctane sulfonic acid
PFOA (aka C8)Perfluorooctanoic acid
PFNAPerfluorononanoic acid
PFHxSPerfluorohexanesulfonic acid
PFHpAPerfluoroheptanoic acid
PFBSPerfluorobutanesulfonic acid

What are PFAS?

Per- and PolyFluorAlkyl Substances or PFAS, are a group of numerous human-made chemicals used since the 1950s to manufacture stain-resistant, water-resistant, and non-stick products.  Because these chemicals have been used in many consumer products, most people have been exposed to them. PFAS have been detected in wastewater and even in rainfall. PFAS stay in the environment for a long time and do not break down easily. As a result, PFAS may be widely detected in soil, water, air, and food. While consumer products and food are the largest source of exposure to these chemicals for most people, drinking water can be an additional source in communities where PFAS are present in water supplies. So far, over two dozen community water systems in Massachusetts have sources testing over 20 ng/L of PFAS.

What contains PFAS?

Food Packaging Icon Food Packaging | Cookware Icon Non-Stick Cookware | Clothes Icon  Waterproof Clothing

  Personal Care Icon Personal Care Products | Fire Extinguisher Icon    Fire-Fighting Foam

  • Food packaged in PFAS-containing materials, processed with equipment that used PFAS, or grown in PFAS-contaminated soil or water.
  • Commercial household products, including stain- and water-repellent fabrics, nonstick products (e.g., Teflon), polishes, waxes, paints, cleaning products, and fire-fighting foams (a major source of groundwater contamination at airports and military bases where firefighting training occurs).
  • Workplace, including production facilities or industries (e.g., chrome plating, electronics manufacturing or oil recovery) that use PFAS.
  • Drinking water, typically localized and associated with a specific facility (e.g., manufacturer, landfill, wastewater treatment plant, firefighter training facility).
  • Living organisms, including fish, animals and humans, where PFAS have the ability to build up and persist over time.

Certain PFAS chemicals are no longer manufactured in the United States as a result of phase outs including the PFOA Stewardship Program in which eight major chemical manufacturers agreed to eliminate the use of PFOA and PFOA-related chemicals in their products and as emissions from their facilities. Although PFOA and PFOS are no longer manufactured in the United States, they are still produced internationally and can be imported into the United States in consumer goods such as carpet, leather and apparel, textiles, paper and packaging, coatings, rubber and plastics.

How are PFAS measured? 

In order to understand what a chemical measurement means, one needs to have a basic understanding of the type of measuring units used, and what they mean. As mentioned above, most of our contaminants are measured using concentration units, such as ppm, ppb, ppt, mg/L, ug/L and ng/L.  What do these units mean in plain English?

Well for starters there are several that are equivalent to one another. In this case ppm = mg/L, ppb = ug/L and  ppt = ng/L. Unfortunately, in some circumstances it is customary to use one unit format where in another case it is customary to use the other which can add to confusion.  One example we can use is the liquid chlorine added to our water during the treatment process. This is customarily reported in ppm or parts per million and has a target of value of 1.0 ppm. This value refers to one part of chemical (in this case liquid chlorine) found in one million parts of our water.  This is equivalent to 1 mg/L (milligram/Liter).  Standards for PFAS levels in drinking water are customarily given in units of ng/L (nanograms/Liter) which is equivalent to parts per trillion or ppt.

Continue to check this page, the DPW Home page and our Twitter account @wellesleydpw for updates.