The map shows the 99 cities and towns that contain one or more public water systems (PWS) that the state has officially declared exceed the standard for PFAS. These municipalities represent over 20% of the state's population. The state currently regulates six long-chain chemicals:
- Perfluorooctane sulfonic acid (PFOS)
- Perfluorooctanoic acid (PFOA)
- Perfluorohexane sulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorodecanoic acid (PFDA)
Below is the distribution of the 176 public water systems that have exceeded the Maximum Contamination Level (MCL) in finished water by city and town as of January 30, 2026 plus one that exceeded in raw water and received a state treatment grant. These systems have taken or will take action to bring them into immediate and long-term compliance.
While these communities are the focus of DEP efforts to provide safe drinking water, the impact of these six PFAS chemicals is much wider as shown on this map.
| Community | Number of Water Systems Exceeded |
| Acton | 3 |
| Attleboro | 1 |
| Avon | 1 |
| Ayer | 3 |
| Barnstable | 3 |
| Bedford | 1 |
| Bellingham | 1 |
| Berlin | 1 |
| Bolton | 2 |
| Boxborough | 13 |
| Boxford | 1 |
| Braintree | 1 |
| Bridgewater | 1 |
| Brockton | 2 |
| Burlington | 1 |
| Cambridge | 1 |
| Carlisle | 5 |
| Carver | 3 |
| Charlton | 1 |
| Chatham | 1 |
| Chelmsford | 2 |
| Clarksburg | 1 |
| Cohasset | 1 |
| Danvers | 1 |
| Dover | 2 |
| Dudley | 2 |
| Duxbury | 1 |
| Eastham | 4 |
| Easton | 1 |
| Egremont | 1 |
| Foxborough | 1 |
| Franklin | 1 |
| Freetown | 1 |
| Gill | 1 |
| Grafton | 2 |
| Granby | 1 |
| Groton | 2 |
| Hanover | 1 |
| Harvard | 2 |
| Holland | 1 |
| Holliston | 1 |
| Hopkinton | 4 |
| Hudson | 1 |
| Lakeville | 3 |
| Lanesborough | 1 |
| Leicester | 1 |
| Littleton | 1 |
| Lynnfield | 1 |
| Mansfield | 1 |
| Mashpee | 2 |
| Mendon | 5 |
| Middleborough | 1 |
| Milford | 1 |
| Millbury | 1 |
| Millis | 1 |
| Millville | 2 |
| Monson | 1 |
| Natick | 1 |
| New Salem | 1 |
| Newbury | 1 |
| North Attleborough | 1 |
| North Reading | 1 |
| Northfield | 1 |
| Norwell | 1 |
| Palmer | 1 |
| Pepperell | 1 |
| Petersham | 1 |
| Phillipston | 1 |
| Plainville | 1 |
| Plymouth | 1 |
| Princeton | 2 |
| Randolph | 1 |
| Raynham | 2 |
| Rehoboth | 3 |
| Rochester | 1 |
| Rockland | 1 |
| Rowley | 1 |
| Sharon | 1 |
| Sherborn | 4 |
| Shirley | 1 |
| Sterling | 1 |
| Stoughton | 1 |
| Stow | 7 |
| Sutton | 2 |
| Swansea | 1 |
| Topsfield | 1 |
| Townsend | 1 |
| Tyngsborough | 8 |
| Wakefield | 1 |
| Wayland | 1 |
| Webster | 1 |
| Wellesley | 3 |
| West Bridgewater | 1 |
| Westford | 3 |
| Westminster | 1 |
| Westport | 7 |
| Wilmington | 1 |
| Woburn | 1 |
| Yarmouth | 1 |
Source: Mass. DEP, "PFAS detected in drinking water supplies in Massachusetts"
Notes:
1) This does not represent current finished drinking water quality, and so does not indicate the population that has been or may be directly exposed to any contaminated water and any associated health risks.
2) The drinking water regulations are expected to be revised this year and the limits will be made stronger which will impact more water systems.