Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water


In October 2020, MassDEP finalized a Maximum Contaminant Level (MCL) for the sum of 6 PFAS compounds in drinking water of 20 nanograms per liter (ng/L) or parts per trillion (ppt). These compounds, also referred to as “PFAS6”, are depicted in the chart below. 

Most recent PFAS results for Concord MA

This new regulation also required all Public Water Systems (PWS) in the state of Massachusetts to begin sampling for PFAS in 2021. Concord Water began initial monitoring activities in April 2021.  Results of initial monitoring, showed PFAS6 levels consistently below the threshold of 10 PPT.  As a result, in April 2022 MassDEP reduced sampling frequency at groundwater sources to annually.  Nagog Pond will monitored quarterly, as there was no water used in 2021.   Monitoring results will continue to be shared with our customers as they become available. Please see the "Important Documents: Sampling Results" section below for these results.

On June 15, 2022, EPA issued interim updated drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) that replace those EPA issued in 2016. The updated advisory levels, which are based on new science and consider lifetime exposure, indicate that some negative health effects may occur with concentrations of PFOA or PFOS in water that are near zero. These interim health advisories will remain in place until EPA establishes an National Primary Drinking Water Regulation. To see the EPA Press release visit this link.

Questions? See the EPA Q&A on Drinking Water Health Advisories for PFOA, PFOS, GenX Chemicals and PFBS at this link

What are PFAS?

Per- and polyfluoroalkyl substances, commonly referred to as PFAS, are a family of man-made chemicals that have been manufactured and used in a variety of industries and consumer products around the globe since the 1940’s. The ability of PFAS to resist water, grease, and stains led to their widespread use in carpets, furniture fabrics, clothing, cookware, food packaging, personal care products, and even firefighting foams.  This widespread use over several decades accounts for the presence of PFAS in many water supplies in the U.S. PFAS are nicknamed “forever chemicals” because many of them resist breaking down in the environment, and bioaccumulate in organisms, including humans.

What is a part per trillion (ppt)?

It can be hard to wrap our minds around what the concentration of a contaminant actually means. The most commonly used units of measure for drinking water analysis are parts per million (ppm) and parts per billion (ppb), or mg/L and ug/L respectively. To help visualize these concentrations, imagine that 1 ppm is the same as one drop of water in a bucket, while 1 ppb is the same as one drop of water in an Olympic size swimming pool!

PFAS are measured in parts per trillion (ppt) or ng/L. To help visualize this even smaller concentration, imagine one drop of water in roughly 20 Olympic size swimming pools. You can also imagine 1 ppt as 1 inch in 16 million miles (600+ times around the earth), 30 seconds out of every million years, or 1 cent in $10 billion.  

Concentration graphic - ppm and ppb

How am I exposed to PFAS?

Because these chemicals have been used in an array of consumer products, most people have been exposed to them. PFAS can be found in:

  • 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.

PFAS widespread consumer use

PFAS are resilient and do not break down easily in the environment. The two most extensively studied PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), have been phased out of production in the United States; however, they are still manufactured internationally and may be imported in a variety of consumer goods.

Is there PFAS in my drinking water?

As part of a national testing initiative between 2013 and 2015, Concord Water and 170 other public water systems in Massachusetts tested for PFAS. Using the best available methodology at that time (EPA Method 537), samples were analyzed for 5 PFAS compounds with a lower limit of detection of 10-90 parts per trillion (ppt). In 2014, PFAS sampling occurred at all of Concord’s public water supplies; we did NOT detect PFAS in our drinking water.

Since that time, existing analytical methods have been revised and new, more sensitive methods have been developed that can detect PFAS compounds at much lower levels (down to 2 ppt). Concord Water began monitoring for PFAS using the revised method with lower detection limits in April 2021. Results of initial and confirmatory monitoring are available below as part of the "Important Documents: Sampling Results" section of this webpage.

How can I stay updated?

Updates will be posted to this webpage, so please check back periodically. Updates may also be provided via News and Notices; you may sign up to receive News and Notices via email or SMS at if you have not previously registered for this service.

Important Documents:  Sampling Results

Q2 2021 PFAS Results Summary

Q3 2021 PFAS Results Summary

Q4 2021 PFAS Results Summary

Q1 2022 PFAS Results Summary

Q2 2022 PFAS Results Summary

Q3 2022 PFAS Results Summary

2021/2022 Hugh Cargill PFAS Results Summary

Additional Resources:

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Melissa Simoncini
Senior Environmental & Regulatory Coordinator
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Phone: 978-318-3250