City of Cambridge Returns to using its own Water Source

The City of Cambridge has announced that the Water Department will resume using the city-owned water supply on November 19, 2022. Cambridge temporarily switched to Massachusetts Water Resource Authority (MWRA) water on August 30, 2022, as a precautionary measure due to concerns about above-average Per- and Polyfluoroalkyl Substances (PFAS) levels in Cambridge water and supply chain delays for receiving the city’s new Granular Activated Carbon (GAC) filter media, which is proven to remove PFAS6 compounds from water. Earlier this month, contractors began installing new GAC media at the Walter J. Sullivan Water Treatment Facility, and as a result, the current PFAS6 levels in the treated water from city-owned water reservoirs are now equivalent to the MWRA water quality regarding the PFAS6 compounds.

“Massachusetts has some of the strictest PFAS standards in the country, and the City of Cambridge is committed to providing high-quality water to our community,” said Yi-An Huang, Cambridge City Manager. “I’m proud of the team’s dedication and hard work over these months, and my children and I continue to drink our City’s tap water with confidence.”

Cambridge’s finished water PFAS6 level in August, before the installation of the new media, was 17.1ppt. With the new GAC filter media installed, the Cambridge Water Departments PFAS6 level is now under 5ppt with only two of the six filters completed. The city expects continued reductions in PFAS levels as GAC media is installed in the remaining filters. in two of the six filters, the combined total of all PFAS6 compounds in treated water from these filters is now at a non-detect level. The city expects continued reductions in PFAS levels in the treated water as GAC media is installed in the remaining filters over the next two months.

“GAC filter media is very effective for removing PFAS from drinking water when used in conjunction with other pretreatment methods currently used in Cambridge,” said Sam Corda, Managing Director of the Cambridge Water Department. “This type of filter media has always been part of the Cambridge water treatment facility’s operating design, and more frequent GAC media replacement is now a part of our preventative maintenance practice to ensure we can remove PFAS from our drinking water.”

Cambridge treats its water by using a series of processes, including pretreatment utilizing Dissolved Air Flotation to remove naturally-occurring organics and suspended solids; primary disinfection with Ozone to disinfect the water and inactivate viruses and bacteria; filtration with GAC filter media to further remove any organics and particles in the water as well as PFAS6;  followed by secondary disinfection with Chloramines to ensure that the water in the distribution system is free of bacteria and viruses.

“Our 24-square-mile watershed located in Lexington, Lincoln, Waltham, and Weston is one of Cambridge’s greatest resources,” said Owen O’Riordan, Acting Deputy City Manager. “Like many communities in Massachusetts and across the country, we are working to address PFAS6 compounds, and the new GAC filter media will greatly assist our efforts to continue meeting all federal and state standards and reducing PFAS6 levels in drinking water. Fortunately, the Cambridge Water Department has been proactively working on a plan since 2019 to design, test, and install the new GAC media to address this issue.”

Like many public water suppliers, the Cambridge Water Department has been aware of the emergence of PFAS6 as contaminants of concern in recent years and the department has complied with state and federal guidelines and subsequent regulations since PFAS6 compounds were identified in Cambridge’s water in 2019.

Cambridge continuously tests its water to ensure compliance with US Environmental Protection Agency and Massachusetts Department of Environmental Protection regulations and typically surpasses all 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. Annually, all water users in the city receive a detailed water quality report by mail in June.

The temporary switch to MWRA water cost the city approximately $7 million, and the newly installed GAC filter media cost $1.5 million.

For more information about PFAS or the Cambridge Water Department, visit  https://www.cambridgema.gov/Water.