Acton Water District brings third PFAS treatment facility online, officials say

Acton Water District officials toured the South Acton water treatment facility and described a newly completed system to remove PFAS from the town’s drinking water. District manager Matt Mastola said the site is one of three Acton plants now equipped to remove PFAS and that the new South Acton unit helps the district meet state treatment expectations dating to about 2020.

"This is our South Acton water treatment facility," Mastola said during the tour, adding the site can produce up to 2,000,000 gallons per day and supplies roughly 70 percent of Acton’s drinking water. He described six granular activated carbon (GAC) vessels — each holding about 30,000 pounds of media — that trap PFAS compounds as water passes through a two-stage filtration train.

The district described how spent GAC is handled: Mastola said the vendor Calgon Carbon will retrieve exhausted media and thermally treat it at a Mid‑Atlantic facility to remove PFAS, then reuse the carbon in other applications. "They will take it back to one of their facilities in Pennsylvania or somewhere else in the Mid‑Atlantic and they will treat it at a very high temperature to burn off the PFAS compounds," he said.

Officials gave a timeline and cost overview: pilot testing began in 2021, voters approved design and funding in 2023, construction began in summer 2024 and the South Acton unit reached operation after about a year and a half. Mastola said the district has spent about $20,000,000 on PFAS retrofits across three plants and that the South Acton facility’s construction cost is just under $8,000,000. He also said the district has invested more than $50,000,000 in water treatment over the last 15 years.

Mastola described financing assistance from the state: the district received a 20‑year, 0 percent loan through the Clean Water Trust and he said approximately $22,400,000 of that loan amount was forgiven, leaving roughly $18,000,000 to be financed for the projects.

Sean Case, the district’s environmental analyst, described secondary water‑quality benefits from GAC. He said the media removes trace organics and minerals that can react with chlorine to form disinfection byproducts; quarterly testing remains well below maximum contaminant levels and the district has observed reductions in those byproducts since using GAC.

On operational details, Mastola said the initial pilot estimated carbon life at about 18 months, but actual operation at another district facility has required carbon replacement after about nine to 11 months because non‑PFAS constituents also adsorb to the media. He estimated ongoing operations and maintenance of the PFAS systems will cost on the order of $500,000 to $1,000,000 per year and said the district will refine that estimate as facilities run.

Case and Mastola also addressed private‑well owners: the district supplies about 95 percent of Acton’s population, but private bedrock wells remain and can be challenging and expensive for homeowners to test for PFAS. Case said sampling of newer bedrock sources has shown reduced PFAS concentrations in some cases, but recommended homeowners follow guidance and testing resources posted by the district.

The district plans public information outreach: Case said customers will receive the district’s 2025 "summer water words" consumer confidence report containing 2025 water‑quality data, but that those results were sampled before the new treatments at South Acton and Center Acton came online. "You’ll see detections in this water quality report, but, right now, out in our system, PFAS is completely undetectable in drinking water through all the testing that we've been doing," he said.

Officials urged residents to consult the Acton Water District website for details about testing, the CCR and steps residents can take to reduce PFAS release, such as avoiding disposing of non‑human waste down toilets and choosing products labeled PFAS‑free. The segment closed with the host thanking the district staff and encouraging viewers to ask questions and review posted information for updates.

Next steps: the district will continue to monitor filter life, operating costs and distribution testing, and will report results in forthcoming consumer confidence reports and public updates.