PFAS Information

Cambridge Water Department: Per- and Polyfluoroalkyl Substances (PFAS)

January 22, 2020

The Cambridge Water Department (CWD) detected the total of the six (6) PFAS compounds, as issued for public comment on December 27, 2019 for drinking water, in our finished water being delivered to customers.  After performing our second round of PFAS testing in December 2019 the quarterly average of the compounds is 18.4 ppt, a slight decrease from the previous average.

The City is continuing to pursue an upgrade of the Granular Activated Carbon (GAC) used as a fine filter for our finished drinking water.  Replacing this filtering media is expected to reduce PFAS by a significant amount, likely 50% or more once installed.  The process of selecting an appropriate GAC product has begun. This process includes the following steps:

  •  Submittal and MassDEP approval of a bench scale testing plan to select the best GAC filter media to reduce the PFAS levels in our water – in process
  •  Preform the bench scale testing of various GAC media and make recommendation to MassDEP of a specific media for use in our treatment plant.
  •  Bid out and select a vendor to replace the filter media with the MassDEP approved GAC product.
  •  Replace our filter media.

Our goal is to have the media replaced by the end of calendar year 2020.

In parallel we are looking at the options of determining the source/s of the PFAS compounds to look at any possible shorter-term options to reduce the level of the PFAS compounds in our water.  Unfortunately, the first set of PFAS testing from each of our three (3) reservoirs has not shown any variations where “blending” our water from Stony Brook vs. Fresh Pond will make any significant difference in our PFAS levels.

We have also reviewed the possibility of “blending” Cambridge water with that of the MWRA and this is currently not technically feasible.

November 8, 2019

The Cambridge Water Department (CWD) detected the total of the six (6) PFAS compounds, as proposed in the Massachusetts Contingency Plan (MCP), in our finished water being delivered to customers to be confirmed at 19.9 ppt.

As a result of our voluntary testing for PFAS we have sent the following letter to the Cambridge City Council and Water Board.

Dear City Councilor/Water Board Member:

Massachusetts Department of Environmental Protection (MassDEP) has recently begun a statewide initiative to test drinking water from community water supplies in order to identify a newly prioritized family of chemicals called Per- and Polyfluoroalkyl Substances (PFAS).  As of June 2018 MassDEP adopted minimal safe levels in local drinking water, based on US EPA risk-based standards, of 70 parts per trillion (ppt) when combining the measured concentration of 6 critical members of this class of chemicals.  This standard (70 ppt when all 6 target PFAS compounds are combined) is intended to protect even the most sensitive users, including pregnant women, from adverse health effects, assuming a lifetime of regular tap water consumption.

The combined concentration of these 6 PFAS compounds detected in Cambridge water (19.9 parts per trillion) is well below the current MassDEP and EPA Health Advisory Level for all users (70 parts per trillion) and just below the MassDEP advisory range for public notification (20-70 parts per trillion).  These results for Cambridge water are also below the California Water Resource Council Board’s Notification Level.  It is important to emphasize that the levels observed over duplicate testing rounds are well below the most sensitive and protective risk-based standards used by the US EPA and the Agency for Toxic Diseases Registry (ATSDR).  Keeping with our history of transparent communications with the community, we have voluntarily chosen to follow MassDEP’s communications guidance proposed for water systems that do fall within the 20-70 ppt range.   For this reason, we are sharing these results with City Council, the Cambridge Water Board and all Cambridge households by posting a summary of test results with explanatory narrative on our website and in the June 2020 annual Water Quality Report.

The City is actively pursuing an upgrade of the granular activated carbon (GAC) used as a fine filter for finished drinking water.  Replacing this filtering media is expected to reduce PFAS by a significant amount, likely 50% or more once installed, and would confer co-benefits by reducing the presence of other possible contaminants as well.  The process of selecting an appropriate GAC product will begin in the next few weeks. The GAC upgrade, including MassDEP regulatory review, is expected to be completed later in 2020.

Cambridge Water Department is committed to take the following actions to address the presence of PFAS in our water supply:

  • continue to test for PFAS compounds on a quarterly basis,
  • evaluate the relative contribution of PFAS to our water system from all three sources (Hobbs Brook, Stony Brook and Fresh Pond Reservoirs),
  • run bench scale tests to verify PFAS removal efficiency and duration by comparing several Granular Activated Carbon (GAC) products, and
  • complete the replacement of the Granular Activated Carbon in the Cambridge Water Department’s six filters over the course of the next 12 months.

It is common to find very low levels of man-made PFAS compounds in drinking water supplies, since they are known to degrade very slowly and are commonly found in groundwater and soils surrounding drinking water sources.  For context it is also important to note that many PFAS compounds have previously been used in common products such as stain repellants, nonstick cookware, waterproof clothing, water-resistant food wrappers and containers, and many other household products.  PFAS may also be found in areas impacted by prior use of industrial products such as fire-suppressing foams.  Most uses of PFAS compounds were phased-out 10-15 years ago, replaced with other compounds that are thought to pose fewer health risks.

Given the emerging concerns about PFAS across the country, the City of Cambridge is electing to adopt a thorough communication approach to inform the public about the status of their drinking water and efforts we are proactively taking to ensure the safety of our water supply.  You can read more about Per- and Polyfluoroalkyl Substances (PFAS) on the Cambridge Water Department or MassDEP website.

The following is a discussion about PFAS starting with a background and additional references for your information.


The United States Environmental Protection Agency (EPA) in 2016 published a drinking water Health Advisory Level for two of the PFAS compounds (Perfluorooctanesulfonic acid, PFOS, and Perfluoroocatanoic acid, PFOA) combined at 0.070 micrograms per liter (ug/L) or 70 parts per trillion (ppt). In June 2018, MassDEP issued an Office of Research and Standards Guideline (ORSG) for drinking water of 70 ppt for PFOA, PFOS, PFNA (Perfluorononanoic acid), PFHxS (Perfluorohexanesulfonic acid), and PFHpA (Perfluoroheptanoic acid) combined. The three additional PFAS compounds were included because they share very similar chemical structures and the available data indicates they are likely to exhibit similar toxicities. The ORSG was established to be protective against adverse health effects for all people consuming the water for a lifetime and is also applicable to shorter-term exposures of weeks to months during pregnancy and breast-feeding.

Based on this ongoing evaluation, MassDEP is currently engaged in a number of coordinated, concurrent efforts to inform its final decisions regarding PFAS in drinking water in Massachusetts. The proposed standard for groundwater that is used or may be used as drinking water is 20 ppt for the six (6) PFAS compounds combined: the five (5) compounds noted above, plus perfluorodecanoic acid (PFDA).

Based on current ORSG, MassDEP has recommended:

  • Consumers in sensitive subgroups (pregnant women, nursing mothers and infants) not consume water when levels of the five PFAS compounds, individually or in combination, are above 70 ppt; and,
  • Public water suppliers take steps expeditiously to lower levels of the five PFAS compounds, individually or in combination, to below 70 ppt for all consumers.

  • If the confirmed PFAS level is between the OSRG of 70 ppt and the proposed Massachusetts Contingency Plan (MCP) groundwater cleanup standard of 20 ppt, MassDEP will encourage you to notify your elected officials and consumers to make them aware of the results and updated information on PFAS.  You will be required to monitor quarterly for PFAS and MassDEP will also recommend that you consider what options are available to you to lower the PFAS level in the finished water.
  • If the confirmed PFAS level is below the proposed MCP groundwater cleanup standard of 20 ppt but at or above 10 ppt, MassDEP will recommend that that you evaluate your operations, review source protection practices, monitor at a frequency recommended by the Department and continue routine operations.
  • If the confirmed PFAS level is below 10 ppt, MassDEP will recommend continuance of routine operations.

Additional references:

In July of 2018 the California Water Resources Control Board’s Division of Drinking Water issued a drinking water notification level (NL) of 14 ppt for PFOA and a NL of 13 ppt for PFOS due to liver toxicity and cancer risks (for PFOA) and immunotoxicity risks (for PFOS).

In May of 2019 a law relating to PFAS was passed in Vermont requiring the Agency of Natural Resources (ANR) to adopt an MCL by rule for PFAS compounds.  This new law provides a comprehensive framework to identify PFAS contamination and to issue new rules to govern acceptable levels in surface water and drinking water.  The proposed rule will be available for public comment this fall.  The final proposed rule must be filed with the Secretary of State’s office by February 1, 2020.  The basis for this rule is the Department of Health’s advisory level of 20 ppt for the sum of five PFAS compounds, they include: PFOA, PFOS, PFHxS, PFHpA and PFNA.  These are the same five compounds being considered in MA.

On September 30, 2019 New Hampshire DEP adopted the following PFAS MCLs:

PFHxS (Perfluorohexanesulfonic acid): 18 ppt
PFNA (Perfluorononanoic acid): 11 ppt
PFOS (Perfluorooctanesulfonic acid): 15 ppt
PFOA (Perfluoroocatanoic acid): 12 ppt

The Cambridge Water Department is committed to providing our customers with quality drinking water. As your water supplier, we are working closely with MassDEP to maintain the quality of your water.

For specific health concerns regarding your exposure you may want to consult a health professional, such as your doctor.

For other health-related questions, you may also contact the Cambridge Health Department at 617-665-3838 or visit one of the websites below.

For treatment and process related questions please contact the Water Department at 617-349-4780.

Where can I get more information on PFAS?

MassDEP PFAS Information.

Interstate Technology and Regulatory Council (ITRC). PFAS.

Association of State Drinking Water Administrators PFAS webpage

EPA’s Drinking Water Health Advisories for PFOA and PFOS can be found at:

The Centers for Disease Control and Prevention’s Public Health Statement for PFOS and PFOA can be found at:

For additional information on possible health effects, you may contact the Massachusetts Department Environmental Protection, Office of Research and Standards at 617-556-1165.

For information on the MassDEP Drinking Water Program, you may visit:

or contact the program at or 617-292-5770.

Additional Information & PFAS Fact Sheet