Per- and Polyfluoroalkyl Substances (PFAS)


UPDATE - August 8, 2021

The Department of Public Works has received certification from MassDEP for the PFAS testing results of the drinking water samples taken July 21st.  The Springvale Water Treatment Facility sample showed a PFAS detection of 21.18 ng/l, which is above MassDEP's MCL, or highest amount allowed by regulation (set at 20 ng/l).  The Elm Bank Treatment Facility sample showed a PFAS detection of 12.34 ng/l, which is below the MCL.

It is important to note that these resent results do not trigger any action or change of use from water customers.  Water from all three active treatment plants combine in Natick’s drinking water distribution system.  The most recent quarterly average, for every treatment plant, remains below the MCL.

Natick is in the process of installing Granulated Activated Carbon (GAC) filters, and a building to house them, in order to remove PFAS at the Springvale Water Treatment Plant. This filtration system is anticipated to be complete and in service by November 2021.

In the meantime, Natick continues to adjust operations in order to deliver the lowest PFAS levels to the most consumers. Natick monitors each individual well based on PFAS levels and continues to adjust the blending based on the most recent monthly results.  Most recent confirmed monthly results will continue to be available on the Town’s PFAS webpage.  August samples will be collected August 18th.

In total 91,847,000 gallons of water was supplied and delivered for the month of July with an average of 3.3 million gallons per day (peak day volume was 3.7 MGD).  46% of the total volume was supplied from the Elm Bank (Charles River) source.  52% of the total volume was supplied from the Springvale Facility.


A public forum was held on May 26 to present information and discuss corrective actions taken.  At the meeting, Town staff and and a panel of experts presented information and helped answer questions.

Presentation Slides May 26 PFAS Public Information Meeting

Video Recording May 26 PFAS Public Information Meeting

Passcode: zL6?VSJd

UPDATE - MAY 4, 2021

Our first quarter of PFAS testing in 2021 (January, February, and March) resulted in two of our four active entry points (known as H&T and Tonka) exceeding the MassDEP maximum contaminant level (MCL) of 20 ppt for PFAS6.

Due to this quarterly exceedance, we were issued a Notice of Noncompliance by MassDEP on April 9, 2021. As required, we mailed a Public Notification ( to all Natick customers on May 1, 2021.

During the Spring 2021 Annual Town Meeting, members approved funding for the first phase of the planned removal of PFAS6 from the drinking water. This funding will finance the installation of Granulated Activated Carbon (GAC) filters to remove PFAS6 from the H&T entry point to the drinking water system (one of the two active entry points that has exceeded the MCL). This new filter system and building are anticipated to be installed and operational by October/November of 2021. This will help by lowering PFAS6 levels in the drinking water while we continue to monitor PFAS levels and plan future steps to maintain these lower levels.


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: MassDEP link.  In October 2020, MassDEP promulgated a new drinking water standard for the sum of six PFAS compounds (PFAS6).  This new standard requires all Massachusetts public water suppliers test for PFAS.  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.

The Natick Water Division proactively sampled for PFAS based on the new state MassDEP regulation and Maximum Contaminant level (MCL) of 20 ppt. We began the process of initial sampling in November 2020 and confirmation sampling in December 2020 on all production wells and treatment plants serving our system. We are now taking monthly PFAS samples, which began January 2021. When available, the latest results will be posted on the Natick website.

With relatively recent advances in laboratory testing, the presence of PFAS can be found in parts per trillion whereas in the past it would be undetected in parts per million or billion.  In 2013, the Department tested for PFAS at the higher level parts per billion and found no detects. 


According to the United States Environmental Protection Agency, PFAS are a group of man-made chemicals that includes PFOA, PFOS, and many other chemicals. PFAS have been manufactured and used in a variety of industries around the globe, including in the United States since the 1940s. PFOA and PFOS have been the most extensively produced and studied of these chemicals. Both chemicals are very persistent in the environment and in the human body – meaning they don’t break down and they can accumulate over time. There is evidence that exposure to PFAS can lead to adverse human health effects.


    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.


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 and ppb.  But what is a ppm, ppb, or ppt for that matter, in plain English?

As an example, let’s use an example of liquid chlorine added to our water in the treatment process at 1.0 ppm. This value refers to one part of chemical (in this case liquid chlorine) found in one million parts of our water. To realize how small a value this actually is and how difficult this contaminate is to trace in the environment, read the analogies listed below:

One part per million (ppm) equals:

    1 inch in 16 miles

One part per billion (ppb) equals:

    1 inch in 16,000 miles

One part per trillion (ppt) equals:

    1 inch in 16 million miles (600+ times around the earth)


Public Education: Link

The Public Education Brochure provided to Natick water consumers on February 3, 2021 is a required notice by the MassDEP. We understand it is complicated and perhaps unexpected. The highlights may be summarized below:

  • The Natick Water Division proactively sampled for PFAS based on the new state MassDEP regulation and Maximum Contaminant level (MCL) of 20 ppt. There is no regulation or MCL set at the federal Environmental Protection Agency (EPA) level. Initial and confirmation PFAS testing was conducted at all production wells and treatment plants serving our system.
  • PFAS exposure can occur from drinking water and many other sources in the home and some workplaces. We began the process of initial sampling in November 2020 and confirmation sampling in December 2020. We are now taking monthly PFAS samples, which began January 2021. When available, the latest results and updates will be posted on the Natick website.
  • The MassDEP standard is currently focused on the sum of six, out of thousands of PFAS compounds believed to exist. The six compounds include Perfluorooctane sulfonic acid (PFOS), and Perfluorooctanoic acid (PFOA), Perfluorononanoic acid (PFNA), Perfluorohexanesulfonic acid (PFHxS), Perfluoroheptanoic acid (PFHpA), and Perfluorodecanoic acid (PFDA).
  • In our initial testing, all of our five water treatment plants have shown the presence of PFAS but the results indicate that only one of our four active treatment plants is above the MassDEP drinking water regulatory limit of 20 parts per trillion (ppt) for six PFAS compounds (known as PFAS6).
  • We have immediately taken action to minimize, to the extent possible, the exposure to PFAS by limiting use of certain source water with elevated levels of PFAS6.
  • PFAS as a chemical class are still considered an emerging contaminant and the ability to reliably collect and test for PFAS in the parts per trillion range (ppt) is relatively new and has challenging protocols. It will take time to generate sufficient data, confirm valid data, and interpret the results. PFAS is also the first time we as public water suppliers have been tracking a contaminant at the ppt level. Typically, water suppliers work with contaminants in the part per million (ppm) and part per billion (ppb) concentrations.
  • If you are in the sensitive subgroup (defined as pregnant or nursing women, infants and people diagnosed by their health care provider to have a compromised immune system), MassDEP advises not to consume water with greater than 20 ppt of the six PFAS substances of concern. You should consult with your health care provider for advice for your particular situation.
  • Using bottled water that has been tested as PFAS free is recommended for the sensitive subgroup to use for drinking, cooking foods that absorb water, and preparing infant formula. The MassDEP website provides this link to commercial brands of bottled water that tests for PFAS. There are also home water treatment filters capable of removing PFAS from drinking water for the countertop or under the sink. Treatment systems and devices are not specifically designed to meet Massachusetts’ drinking water standard of 20 ppt for PFAS6. There are systems that have been designed to meet the USEPA’s Health Advisory of 70 ppt for the sum of PFOS and PFOA. MassDEP bottled water and home filters link:
  • The Town of Natick is ahead of many communities in the early stages of addressing PFAS and will provide updates as new information is available. Please sign up for email updates by signing up for Natick’s WaterSmart at
  • Natick Water Division has started to take the steps necessary to evaluate treatment options available to Natick to lower the levels of PFAS in the drinking water. This includes conducting several pilot studies to determine the most effective method of removal. The anticipation is that any permanent filtering solution, if desired, could take upwards of a year or more to complete.

Please read the FAQ section (link) for additional PFAS updates on this page as hopefully you will find these useful. If you have further questions or suggestions, please call the Natick Water Division at: 508-647-6557


Natick’s drinking water comes from eleven ground water wells and the water is treated at four different treatment facilities.  Located throughout Natick, the four facilities are named Springvale, Elm Bank, Pine Oaks, and Morses Pond (currently off line).  Springvale is the primary facility and is comprised of two independent treatment trains known as H&T filters and Tonka filters.  The system of pipes that carries drinking water to homes and businesses is called the distribution system.  The distribution system in Natick is contiguous, one system all connected together.  The distribution system also has two storage reservoirs, one on Broads Hill and one in Town Forest.  The water that is treated at individual treatment facilities is pumped through the distribution system and is mostly mixed prior to domestic consumption.  Any excess water is stored in the reservoirs.  Depending on pump rates, time of day demands, and which treatment facilities are running, you may receive more water from one facility or another.  It is not possible to determine precisely which treatment plant is suppling water to your tap.  Below is a link to a map showing the well and treatment facility locations.

Natick Drinking Water Source Map


To receive future updates regarding PFAS please sign up for the free WaterSmart notification program at: . This free water use tracking tool helps residents monitor usage, identify leaks, conserve water, and receive notifications regarding your water supply.

Specific questions may also be sent to with “PFAS” in the subject line.