We analyzed tap water quality data for hundreds of cities in Massachusetts to identify the 25 with the most contaminants exceeding health guidelines. This ranking is based on 2026 data from the EPA and EWG databases.
While all public water systems must meet EPA legal limits, many health experts — including the Environmental Working Group — argue that these legal limits are outdated and don't reflect current scientific understanding of safe exposure levels. The cities below have the widest gap between what's in their water and what's considered safe by modern health standards.
Rankings at a Glance
Hudson, Massachusetts
Hudson has 21 contaminants exceeding EWG health guidelines out of 46 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Hudson water report →Acton, Massachusetts
Acton has 21 contaminants exceeding EWG health guidelines out of 43 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Acton water report →Westborough, Massachusetts
Westborough has 21 contaminants exceeding EWG health guidelines out of 41 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Westborough water report →Hopedale, Massachusetts
Hopedale has 21 contaminants exceeding EWG health guidelines out of 40 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Hopedale water report →Rockland, Massachusetts
Rockland has 20 contaminants exceeding EWG health guidelines out of 40 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Rockland water report →Bridgewater, Massachusetts
Bridgewater has 20 contaminants exceeding EWG health guidelines out of 39 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Bridgewater water report →Bellingham, Massachusetts
Bellingham has 20 contaminants exceeding EWG health guidelines out of 39 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Bellingham water report →West Newbury, Massachusetts
West Newbury has 20 contaminants exceeding EWG health guidelines out of 36 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full West Newbury water report →Foxborough, Massachusetts
Foxborough has 20 contaminants exceeding EWG health guidelines out of 34 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Foxborough water report →Rowley, Massachusetts
Rowley has 20 contaminants exceeding EWG health guidelines out of 34 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Rowley water report →Auburn, Massachusetts
Auburn has 20 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Auburn water report →Hanover, Massachusetts
Hanover has 19 contaminants exceeding EWG health guidelines out of 42 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Hanover water report →Walpole, Massachusetts
Walpole has 19 contaminants exceeding EWG health guidelines out of 39 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Walpole water report →Ipswich, Massachusetts
Ipswich has 19 contaminants exceeding EWG health guidelines out of 38 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Ipswich water report →Concord, Massachusetts
Concord has 19 contaminants exceeding EWG health guidelines out of 36 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Concord water report →Peabody, Massachusetts
Peabody has 19 contaminants exceeding EWG health guidelines out of 35 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Peabody water report →Billerica, Massachusetts
Billerica has 19 contaminants exceeding EWG health guidelines out of 35 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Billerica water report →North Reading, Massachusetts
North Reading has 19 contaminants exceeding EWG health guidelines out of 34 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full North Reading water report →Scituate, Massachusetts
Scituate has 19 contaminants exceeding EWG health guidelines out of 33 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Scituate water report →Norwell, Massachusetts
Norwell has 19 contaminants exceeding EWG health guidelines out of 33 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Norwell water report →Cambridge, Massachusetts
Cambridge has 19 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Cambridge water report →Burlington, Massachusetts
Burlington has 19 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Burlington water report →Westford, Massachusetts
Westford has 19 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Westford water report →North Chelmsford, Massachusetts
North Chelmsford has 19 contaminants exceeding EWG health guidelines out of 29 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full North Chelmsford water report →Wilmington, Massachusetts
Wilmington has 18 contaminants exceeding EWG health guidelines out of 41 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Wilmington water report →What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Bromodichloromethane, Chloroform, Dibromoacetic acid. These appear repeatedly across different water systems and regions.
Water quality varies significantly even within the same state, driven by local geology, agricultural activity, and industrial proximity.
Across all ranked cities, 489 contaminant readings exceed EWG health guidelines, but only 27 exceed EPA legal limits. This gap of 462 highlights how legal standards may not fully protect public health — EPA limits haven't been updated for many contaminants in decades.
Full Rankings Table
| Rank | City | State | Detected | Above Guidelines | Above Legal | People Served |
|---|---|---|---|---|---|---|
| 1 | Hudson | MA | 46 | 21 | 1 | 18,406 |
| 2 | Acton | MA | 43 | 21 | 2 | 20,890 |
| 3 | Westborough | MA | 41 | 21 | 0 | 18,272 |
| 4 | Hopedale | MA | 40 | 21 | 2 | 6,025 |
| 5 | Rockland | MA | 40 | 20 | 2 | 33,887 |
| 6 | Bridgewater | MA | 39 | 20 | 2 | 26,563 |
| 7 | Bellingham | MA | 39 | 20 | 1 | 15,390 |
| 8 | West Newbury | MA | 36 | 20 | 0 | 2,895 |
| 9 | Foxborough | MA | 34 | 20 | 2 | 16,924 |
| 10 | Rowley | MA | 34 | 20 | 1 | 6,325 |
| 11 | Auburn | MA | 32 | 20 | 2 | 11,763 |
| 12 | Hanover | MA | 42 | 19 | 2 | 14,899 |
| 13 | Walpole | MA | 39 | 19 | 0 | 23,989 |
| 14 | Ipswich | MA | 38 | 19 | 0 | 13,127 |
| 15 | Concord | MA | 36 | 19 | 0 | 16,402 |
| 16 | Peabody | MA | 35 | 19 | 0 | 52,474 |
| 17 | Billerica | MA | 35 | 19 | 1 | 40,243 |
| 18 | North Reading | MA | 34 | 19 | 0 | 15,500 |
| 19 | Scituate | MA | 33 | 19 | 0 | 19,688 |
| 20 | Norwell | MA | 33 | 19 | 2 | 11,258 |
| 21 | Cambridge | MA | 32 | 19 | 1 | 105,162 |
| 22 | Burlington | MA | 32 | 19 | 2 | 25,392 |
| 23 | Westford | MA | 32 | 19 | 1 | 18,000 |
| 24 | North Chelmsford | MA | 29 | 19 | 1 | 7,287 |
| 25 | Wilmington | MA | 41 | 18 | 2 | 22,325 |
Frequently Asked Questions
What city has the worst tap water in Massachusetts?
Based on 2026 data, Hudson, MA has the most contaminants exceeding EWG health guidelines among the cities we analyzed.
How are cities ranked in this report?
Cities are ranked by the number of contaminants exceeding EWG health guidelines. These guidelines are typically stricter than EPA legal limits and reflect current scientific research on safe exposure levels.
Is my tap water safe if my city isn't on this list?
Not necessarily. Even cities not on this list may have contaminants of concern. We recommend checking your specific water quality using our free water scan tool.
What's the best water filter for contaminated water?
A reverse osmosis (RO) system is the most effective for removing the widest range of contaminants. For whole-home protection, a combination of RO for drinking water and a whole-home filter for showers and baths is recommended.
Related Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: April 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
