PFAS
New Federal Drinking Water Standards for PFAS
The Plymouth Water Division has been closely monitoring a family of chemicals called per- and polyfluoroalkyl substances (PFAS) that have been detected in some public water supplies in Massachusetts and across the nation. PFAS were widely used in manufacturing, many consumer products, and firefighting foam. When discarded, PFAS leached from these products and into water sources. The presence of PFAS is the result of pollution and not any action taken by our water system.
Massachusetts passed a drinking water standard for PFAS in October of 2020 which applies only to Public Water Systems (PWS) in Massachusetts. On Wednesday, April 10th, the United States Environmental Protection Agency (EPA) announced that they finalized a new federal National Primary Drinking Water Rule for PFAS, which will apply to PWS across the country. EPA’s Maximum Contaminant Level (MCL) for PFAS compounds, PFOA and PFOS, at 4 parts per trillion (ppt), and PFNA, PFHxS, and HFPO-DA (GenX Chemicals) at 10 ppt, are quite a bit lower than the Massachusetts MCL of 20 ppt for the sum of six PFAS compounds, which is referred to as PFAS6. EPA’s standard also includes a MCL for PFAS compounds PFHxS, PFNA, HFPO-DA (GenX Chemicals), and PFBS expressed as a Hazard Index. The Hazard Index for the sum of the hazard quotients for these compounds must be less than or equal to one.
The Plymouth Water Division has been monitoring for PFAS since the Massachusetts standard took effect and our most recent results, from October 2024, are below. Only water supply sources with a regulated PFAS detection are shown in the table. All other water sources had no regulated PFAS detections in the most recent sampling.
| Compound | Current MassDEP Standard | EPA Standard | Wannos Pond Well | North Plymouth Well | PWS Meets Standard? |
|---|---|---|---|---|---|
| PFOA | Combined 20 ppt | 4 ppt | 2.39 ppt | 1.93 ppt | Yes |
| PFOS | Combined 20 ppt | 4 ppt | Non Detect | Non Detect | Yes |
| PFNA | Combined 20 ppt | 10 ppt / Hazard Index (HI) ≤ 1 | Non Detect | Non Detect HI = 0.0032 | Yes |
| PFHxS | Combined 20 ppt | 10 ppt / Hazard Index (HI) ≤ 1 | Non Detect | Non Detect HI = 0.0032 | Yes |
| PFHpA | Combined 20 ppt | No EPA Standard | Non Detect | Non Detect | Yes |
| PFDA | Combined 20 ppt | No EPA Standard | Non Detect | Non Detect | Yes |
| PFBS | No MA Standard | Hazard Index (HI) ≤ 1 | Non Detect | HI = 0.0032 | Yes |
| HFPO-DA (GenX Chemicals) | No MA Standard | 10 ppt / Hazard Index (HI) ≤ 1 | Non Detect | Non Detect HI = 0.0032 | Yes |
In Massachusetts, the Department of Environmental Protection (MassDEP) administers the federal Safe Drinking Water Act. MassDEP must be at least as stringent with their standard as EPA and will have up to two years to adopt the new lower standard to comply with EPA’s primacy requirements. MassDEP has indicated they will convene a stakeholder group to advise them on adoption of new standards (MassDEP could choose to be more stringent than EPA or could act more quickly to adopt the standards than EPA allows). We expect to learn more about MassDEP’s process in the coming weeks.
Now that a federal standard has been adopted, PWS across the country will be grappling with how to come into compliance with the new standards. What does this mean for our water system?
Given our sampling results have reliably and consistently been below EPA’s standards, the Plymouth Water Division expects that we would be in compliance should MassDEP adopt the same standards that EPA just adopted.
The research and understanding into potential health impacts of PFAS continues to evolve. When a water source contains PFAS above the Massachusetts standard, the Massachusetts Department of Environmental Protection recommends consumers in a sensitive subgroup (pregnant or nursing women, infants and people diagnosed by their health care provider to have a compromised immune system), are advised not to consume, drink, or cook with water when the level of PFAS6 is above 20 ppt. As our scientific understanding evolves, further guidance may be issued. Consumers concerned about potential health effects of PFAS should consult a medical professional.