We analyzed tap water quality data for hundreds of cities in Maine 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EPA legal limits, many health experts — including the Environmental Working Group — argue that these legal limits are outdated and don't reflect current scientific understanding of safe exposure levels.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
Augusta, Maine
Augusta 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 Augusta water report →Charleston, Maine
Charleston has 13 contaminants exceeding EWG health guidelines out of 18 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Charleston water report →Hampden, Maine
Hampden has 12 contaminants exceeding EWG health guidelines out of 23 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Hampden water report →Gardiner, Maine
Gardiner has 12 contaminants exceeding EWG health guidelines out of 20 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Gardiner water report →Hallowell, Maine
Hallowell has 12 contaminants exceeding EWG health guidelines out of 18 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Hallowell water report →Kennebunk, Maine
Kennebunk has 12 contaminants exceeding EWG health guidelines out of 17 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Kennebunk water report →Searsport, Maine
Searsport has 12 contaminants exceeding EWG health guidelines out of 14 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Searsport water report →Topsham, Maine
Topsham has 11 contaminants exceeding EWG health guidelines out of 23 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Topsham water report →Sanford, Maine
Sanford has 11 contaminants exceeding EWG health guidelines out of 23 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Sanford water report →Boothbay, Maine
Boothbay has 11 contaminants exceeding EWG health guidelines out of 19 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Boothbay water report →Carrabassett Valley, Maine
Carrabassett Valley has 11 contaminants exceeding EWG health guidelines out of 18 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Carrabassett Valley water report →Yarmouth, Maine
Yarmouth has 11 contaminants exceeding EWG health guidelines out of 16 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Yarmouth water report →South Berwick, Maine
South Berwick has 11 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full South Berwick water report →Limerick, Maine
Limerick has 11 contaminants exceeding EWG health guidelines out of 14 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Limerick water report →Belfast, Maine
Belfast has 10 contaminants exceeding EWG health guidelines out of 18 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Belfast water report →West Gardiner, Maine
West Gardiner has 10 contaminants exceeding EWG health guidelines out of 18 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full West Gardiner water report →York, Maine
York has 10 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full York water report →Winterport, Maine
Winterport has 10 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Winterport water report →Mechanic Falls, Maine
Mechanic Falls has 10 contaminants exceeding EWG health guidelines out of 14 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Mechanic Falls water report →Newport, Maine
Newport has 10 contaminants exceeding EWG health guidelines out of 14 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Newport water report →Bangor, Maine
Bangor has 9 contaminants exceeding EWG health guidelines out of 18 total detected, placing it among the most concerning water supplies analyzed.
See full Bangor water report →Biddeford, Maine
Biddeford has 9 contaminants exceeding EWG health guidelines out of 15 total detected, placing it among the most concerning water supplies analyzed.
See full Biddeford water report →Old Town, Maine
Old Town has 9 contaminants exceeding EWG health guidelines out of 15 total detected, placing it among the most concerning water supplies analyzed.
See full Old Town water report →Sebattus, Maine
Sebattus has 9 contaminants exceeding EWG health guidelines out of 15 total detected, placing it among the most concerning water supplies analyzed.
See full Sebattus water report →Kittery, Maine
Kittery has 9 contaminants exceeding EWG health guidelines out of 14 total detected, placing it among the most concerning water supplies analyzed.
See full Kittery water report →What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Total trihalomethanes (TTHMs), Haloacetic acids (HAA5), Chloroform. 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, 274 contaminant readings exceed EWG health guidelines, but only 7 exceed EPA legal limits. This gap of 267 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 | Augusta | ME | 29 | 19 | 0 | 15,040 |
| 2 | Charleston | ME | 18 | 13 | 2 | 500 |
| 3 | Hampden | ME | 23 | 12 | 0 | 4,628 |
| 4 | Gardiner | ME | 20 | 12 | 0 | 8,000 |
| 5 | Hallowell | ME | 18 | 12 | 2 | 2,138 |
| 6 | Kennebunk | ME | 17 | 12 | 0 | 35,663 |
| 7 | Searsport | ME | 14 | 12 | 0 | 2,763 |
| 8 | Topsham | ME | 23 | 11 | 0 | 17,943 |
| 9 | Sanford | ME | 23 | 11 | 0 | 14,025 |
| 10 | Boothbay | ME | 19 | 11 | 0 | 9,250 |
| 11 | Carrabassett Valley | ME | 18 | 11 | 1 | 3,115 |
| 12 | Yarmouth | ME | 16 | 11 | 0 | 7,960 |
| 13 | South Berwick | ME | 15 | 11 | 0 | 3,360 |
| 14 | Limerick | ME | 14 | 11 | 0 | 625 |
| 15 | Belfast | ME | 18 | 10 | 0 | 5,095 |
| 16 | West Gardiner | ME | 18 | 10 | 0 | 835 |
| 17 | York | ME | 15 | 10 | 0 | 13,400 |
| 18 | Winterport | ME | 15 | 10 | 0 | 3,228 |
| 19 | Mechanic Falls | ME | 14 | 10 | 0 | 2,125 |
| 20 | Newport | ME | 14 | 10 | 0 | 1,900 |
| 21 | Bangor | ME | 18 | 9 | 0 | 26,868 |
| 22 | Biddeford | ME | 15 | 9 | 0 | 39,605 |
| 23 | Old Town | ME | 15 | 9 | 0 | 7,498 |
| 24 | Sebattus | ME | 15 | 9 | 2 | 25 |
| 25 | Kittery | ME | 14 | 9 | 0 | 14,250 |
Frequently Asked Questions
What city has the worst tap water in Maine?
Based on 2026 data, Augusta, ME 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.
