CWD PFAS FAQ
On November 19, the City of Cambridge returns to sourcing its water from the city-owned water supply reservoirs. The Cambridge Water Department (CWD) has installed new filter media in the Walter J. Sullivan Water Treatment Facility, which has strengthened the ability to reduce PFAS compounds from Cambridge’s water supply. As a result, the current PFAS6 levels are now equivalent to the MWRA water quality regarding the PFAS6 compounds.
Why is the City switching back to its own water supply and stopping the use of MWRA water? What has changed?
With the successful installation of new granular activated carbon (GAC) filter media* test results indicate that Cambridge’s PFAS6 levels are significantly reduced and now comparable to the MWRAs PFAS6 levels. In August CWD switched over to MWRA water due to concerns of above average PFAS levels which have now been abated with the new filter media.
How do the filters work, and how will this new media impact the PFAS levels in drinking water?
The filters work by removing particulate matter by forcing the water to pass through the porous GAC filter media. GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter. For more information on CWDs treatment processes please go to:
https://www.cambridgema.gov/Water/wateroperationsdivision/watertreatment
Will Cambridge see reduced levels of PFAS in its finished drinking water now that the new filter media has been installed?
Yes, CWD has already seen a significant reduction in PFAS6 levels with only two of the six filter media changeouts completed at this time. With the next two filter media changeouts scheduled for November, CWD anticipates further reduction in PFAS levels.
What were the historical levels of PFAS6 prior to MWRA switchover and what is the current level now?
Please see graph below.
Now that the new filter media is installed what levels do you expect moving forward?
With consistent monitoring of the new filter media performance and with appropriate media changeout intervals CWD anticipates PFAS6 levels to be below 5ppt. As a reference the current MassDEP PFAS6 regulation requires that the combined quarterly average should not exceed 20ppt.
Does the Cambridge Water Department make PFAS testing data available to the public?
Yes, CWD posts all water quality testing data including PFAS6 data on the CWD website.
Is my water safe and how can I be assured it continues to be safe?
CWD continuously tests its water to ensure compliance with US Environmental Protection Agency (USEPA) and Massachusetts Department of Environmental Protection (MassDEP) Regulations. Additionally, the Cambridge Water Department has an on-site certified laboratory that tests many water quality parameters to optimize its treatment performance and water quality. If you’re interested in learning more about your water quality, please see the following link to the annual water quality report.
https://www.cambridgema.gov/-/media/Files/waterdepartment/labfiles/2021annualdrinkingwaterqualityreport.pdf
* Filter media is the material used inside a filtration system to remove taste, odor, and contaminants in drinking water. In water treatment, granular activated carbon (GAC) is the most used media for filtration. It can be made from wood, lignite, or coal. It’s an extremely effective adsorbent because it’s a highly porous material and provides a large surface area to which contaminants may adsorb.
On August 30, the City of Cambridge temporarily began sourcing its water from the Massachusetts Water Resource Authority. This week, contractors for the Cambridge Water Department (CWD) started installing new filter media in the Walter J. Sullivan Water Treatment Facility, which will strengthen our ability to remove PFAS from Cambridge’s water supply. The contractor will complete the installation process later this fall.
To help inform residents about PFAS and the city’s water supply, the CWD has created a new set of Frequently Asked Questions (FAQ).
HAS MY WATER BEEN SAFE TO DRINK?
Yes, the water has been and continues to be safe to drink. Many precautions have been introduced by the MassDEP and voluntarily by the City to establish the highest assurance possible that PFAS in drinking water will not pose an elevated risk to the community of water consumers. In addition to, continued compliance with some of the strictest regulatory limits in the US, Cambridge is also in the process of replacing the filter media that has been shown to effectively bring down PFAS concentrations. These improvements have been approved by MassDEP. Cambridge continues to take steps to keep the levels of PFAS in the finished water well below MassDEP limits.
WHY DID CAMBRIDGE MOVE TO MASSACHUSETTS WATER RESOURCES AUTHORITY (MWRA) WATER ON AUGUST 30th AND NOT EARLIER? DID CAMBRIDGE’S WATER SUDDENLY BECOME UNSAFE?
No, Cambridge’s water is safe. We preemptively switched over to MWRA water to potentially avoid an anticipated seasonal increase in our PFAS levels, which typically occurs in September.
IS CAMBRIDGE THE ONLY COMMUNITY DEALING WITH PFAS?
No, there are many communities in Massachusetts, as well as across the country, that are dealing with PFAS compounds. Please see the link below for more information about PFAS in Massachusetts.
https://www.mass.gov/info-details/per-and-polyfluoroalkyl-substances-pfas#pfas-detected-in-drinking-water-supplies-in-massachusetts-
WHY HASN’T THE CITY DONE ANYTHING TO PREVENT PFAS IN OUR WATER and CAN CAMBRIDGE DO ANYTHING TO GET PFAS OUT OF OUR WATER?
Once PFAS was identified in our water system in 2019, the city developed a plan to address it. The plan was to replace the granular activated carbon (GAC) filter media in our existing filters. The new GAC filter media will remove PFAS compounds from the water. Unfortunately, the pandemic and supply shortages has delayed the implementation of this plan.
Yes, we started the process of replacing our GAC filter media on October 11th. We have 6 filters and will replace 2 filters at a time. As each set of filters are updated, we will verify PFAS removal and put them online to reduce the use of MWRA water and then transition fully back to Cambridge water. It is anticipated that by the end of the calendar year we will be back to using 100% Cambridge water.
CAN I HAVE MY WATER AT HOME TESTED FOR PFAS?
There is no need to, we test the PFAS levels leaving the treatment plant, which is same throughout the water system. We do test for lead at individual homes, free of charge to Cambridge residents.
HOW DID PFAS GET INTO OUR WATER SUPPLY AND ELSEWHERE?
Because these compounds have been used for decades in so many types of consumer products and because they do not easily degrade in the environment, they are found in developed areas across the world, travelling easily in groundwater to less developed watersheds.
There are over 4,000 possible Per and Polyfluoroalkyl Substances (PFAS), though many are not actually produced or found in the environment. PFAS compounds are found in many everyday products, typically as a water/stain repellent additive or coating or in other consumer products. PFAS compounds have been historically used in carpeting, clothing, furniture upholstery, food wrappings, and waterproofed camping gear, though many manufacturers are now shifting away from PFAS use entirely. PFAS chemicals were first used in manufacturing in the 1950’s and some of the most potentially harmful (“long-chain PFAS”) were eliminated from the industrial supply chain between 2000-2015. Other PFAS chemicals with similar properties have replaced the most harmful PFAS chemical compounds, but some concerns about these substitute chemicals have been raised more recently.
Fortunately, as a result of the elimination of the most harmful PFAS chemicals in most products and processes, human surveillance studies have seen the body burden of key PFAS compounds in US residents drop between 70-85% since 2000. Protecting the water supply from earlier PFAS releases is of critical public health importance, but much is still unknown about the total exposures from direct contact or ingestion unrelated to drinking water.
WHY IS 20 PPT THE LEVEL OF PFAS IN WATER THAT CAUSES CONCERN? DOES IT MEAN 19 PPT IS SAFE?
The Massachusetts Department of Environmental Protection (MassDEP) issued this PFAS standard for public drinking water, effective January 2021, requiring the quarterly average of the sum of 6 critical PFAS compounds remain below 20 parts per trillion (ppt) in total. The MassDEP has established some of the strictest limits in the country using risk-based methodologies that are very protective of all water consumers. To appreciate how much precaution went into the 20 ppt limit, it’s important to realize that no studies have shown any adverse biological effects (no signs of harm) in subject animals at these levels. Some studies have shown effects at much higher concentrations (at least 1,000 times higher) and much more research is currently underway. The very low limits adopted by MassDEP are largely the result of uncertainty about the mechanism of harm (specific chemical action taking place within the body and its cells), which cell-types or tissues are affected, and which pathways could lead to biological effects in humans over a lifetime. When there aren’t enough toxicological studies of high quality, specific to regulated PFAS, at low doses, and comparing different subject species, the agencies responsible for establishing safe exposure levels (like MassDEP) will add “safety factors” that lower the acceptable allowable limits derived from these animal studies. This process of lowering the level considered safe over a lifetime can result in a regulatory limit that’s 1/10th the level at which no observed health effects are seen in published studies, or 1/100th of this level, or even 1/1000th of this level, depending on the extent of uncertainty from insufficient published research. So, consider that the 20 ppt standard for PFAS6 used by MassDEP is very protective and precautionary since it compensates for many types of uncertainty. The adherence to this precautionary limit should bring a great deal of assurance to those who use Cambridge water. Plans are now underway to replace the filter media that will remove PFAS even further below the current very protective risk-based standard.
WHY DOES CAMBRIDGE HAVE ITS OWN WATER SUPPLY and WHERE DOES OUR WATER COME FROM?
Cambridge wanted to ensure that they had a sufficient water supply for the anticipated growth and purchased the private water company in 1850 and has been operating the Cambridge water system ever since. Originally all the water came from Fresh Pond.
Our water comes from a 24 square mile watershed located in the towns of Lexington, Lincoln, Waltham and Weston. The city built two reservoirs in the late 1800’s Hobbs Brook Reservoir and Stony Brook Reservoir, along with a pipeline to bring water from these two Reservoirs to Fresh Pond.
HOW DOES CAMBRIDGE TREAT ITS WATER IT PROVIDES TO THE COMMUNITY AND HOW DO I KNOW THAT IT IS SAFE TO DRINK?
Cambridge treats it water by using a series of processes as follows: Pretreatment utilizing Dissolved Air Flotation (DAF) to remove naturally-occurring organics and suspended solids; Primary disinfection with Ozone to disinfect the water and inactivate viruses and bacteria; Filtration with Granular Activated Carbon (GAC) filter media to further remove any organics and particles in the water; Secondary disinfection with Chloramines to ensure that the water in the distribution system is free of bacteria and viruses.
We are required to test many parameters for compliance based on US Environmental Protection Agency (USEPA) and MassDEP regulations and exceed all regulations. We also have a certified laboratory which we use to test many water quality parameters to optimize our treatment performance and water quality. We annually send out a water quality report, in June, which summarizes the water quality on an annual basis.
DOES PFAS IMPACT EVERYONE EQUALLY? IF NOT, IS THERE ANYTHING SPECIFIC AT-RISK PEOPLE SHOULD DO?
No, it does not. Individuals with immune deficiencies, pregnant women and infants are typically the most suspectable to the potential effects of PFAS compounds. If you are concerned, you can drink bottled water that has been tested and free of PFAS compounds.
WOULD IT BE CHEAPER AND SAFER TO JUST USE MWRA WATER RATHER THAN HAVING OUR OWN WATER SUPPLY?
No, both water systems are excellent water supplies and surpass the requirements of all USEPA and MassDEP regulations. Additionally, MWRA water costs over 2 ½ times the cost of Cambridge water, a cost that would be passed along to Cambridge water rate payers.
WHY DON’T WE JUST TURN OUR WATER SYSTEM OVER TO THE MWRA?
Both Cambridge and the MWRA are excellent water systems and having the MWRA as a backup system puts Cambridge in a unique position where we have both redundancy and resiliency, which very few water systems have. Operating our own water system allows Cambridge to be in charge of its own destiny and the MWRA water costs significantly more than ours.