We analyzed tap water quality data for hundreds of cities in Pennsylvania 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EPA legal limits, many health experts — including the Environmental Working Group — argue that these legal limits are outdated and don't reflect current scientific understanding of safe exposure levels.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
Brownstown, Pennsylvania
Brownstown has 20 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 Brownstown water report →Quakertown, Pennsylvania
Quakertown 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 Quakertown water report →Bryn Mawr, Pennsylvania
Bryn Mawr has 19 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 Bryn Mawr water report →New Freedom, Pennsylvania
New Freedom 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 New Freedom water report →Horsham, Pennsylvania
Horsham 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 Horsham water report →Lansdale, Pennsylvania
Lansdale has 18 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 Lansdale water report →Warminster, Pennsylvania
Warminster has 18 contaminants exceeding EWG health guidelines out of 37 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Warminster water report →Dover, Pennsylvania
Dover has 18 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 Dover water report →Emmaus, Pennsylvania
Emmaus has 18 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 Emmaus water report →Richboro, Pennsylvania
Richboro has 17 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 Richboro water report →Coraopolis, Pennsylvania
Coraopolis has 17 contaminants exceeding EWG health guidelines out of 37 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Coraopolis water report →Leola, Pennsylvania
Leola has 17 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 Leola water report →Newtown, Pennsylvania
Newtown has 17 contaminants exceeding EWG health guidelines out of 28 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Newtown water report →Gettysburg, Pennsylvania
Gettysburg has 17 contaminants exceeding EWG health guidelines out of 27 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Gettysburg water report →Landisville, Pennsylvania
Landisville has 16 contaminants exceeding EWG health guidelines out of 37 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Landisville water report →Lancaster, Pennsylvania
Lancaster has 16 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 Lancaster water report →Sellersville, Pennsylvania
Sellersville has 16 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 Sellersville water report →Southampton, Pennsylvania
Southampton has 16 contaminants exceeding EWG health guidelines out of 28 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Southampton water report →Spring City, Pennsylvania
Spring City has 15 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 Spring City water report →Philadelphia, Pennsylvania
Philadelphia has 15 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 Philadelphia water report →Kennett Square, Pennsylvania
Kennett Square has 15 contaminants exceeding EWG health guidelines out of 30 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Kennett Square water report →Wilkes Barre, Pennsylvania
Wilkes Barre has 15 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 Wilkes Barre water report →Breinigsville, Pennsylvania
Breinigsville has 15 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 Breinigsville water report →Ambler, Pennsylvania
Ambler has 15 contaminants exceeding EWG health guidelines out of 27 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Ambler water report →Trappe, Pennsylvania
Trappe has 15 contaminants exceeding EWG health guidelines out of 27 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Trappe water report →What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Bromodichloromethane, Dibromoacetic acid, Dibromochloromethane. 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, 422 contaminant readings exceed EWG health guidelines, but only 23 exceed EPA legal limits. This gap of 399 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 | Brownstown | PA | 38 | 20 | 1 | 4,327 |
| 2 | Quakertown | PA | 34 | 20 | 0 | 12,800 |
| 3 | Bryn Mawr | PA | 41 | 19 | 0 | 747,460 |
| 4 | New Freedom | PA | 29 | 19 | 0 | 4,464 |
| 5 | Horsham | PA | 41 | 18 | 0 | 25,000 |
| 6 | Lansdale | PA | 38 | 18 | 1 | 91,941 |
| 7 | Warminster | PA | 37 | 18 | 3 | 40,000 |
| 8 | Dover | PA | 34 | 18 | 1 | 21,097 |
| 9 | Emmaus | PA | 33 | 18 | 4 | 14,000 |
| 10 | Richboro | PA | 38 | 17 | 0 | 36,750 |
| 11 | Coraopolis | PA | 37 | 17 | 1 | 5,804 |
| 12 | Leola | PA | 34 | 17 | 2 | 7,734 |
| 13 | Newtown | PA | 28 | 17 | 1 | 38,500 |
| 14 | Gettysburg | PA | 27 | 17 | 0 | 12,425 |
| 15 | Landisville | PA | 37 | 16 | 1 | 20,988 |
| 16 | Lancaster | PA | 33 | 16 | 1 | 120,000 |
| 17 | Sellersville | PA | 29 | 16 | 0 | 15,000 |
| 18 | Southampton | PA | 28 | 16 | 2 | 16,000 |
| 19 | Spring City | PA | 36 | 15 | 0 | 48,253 |
| 20 | Philadelphia | PA | 35 | 15 | 1 | 1,600,000 |
| 21 | Kennett Square | PA | 30 | 15 | 2 | 6,328 |
| 22 | Wilkes Barre | PA | 29 | 15 | 0 | 134,570 |
| 23 | Breinigsville | PA | 29 | 15 | 0 | 1,475 |
| 24 | Ambler | PA | 27 | 15 | 0 | 20,000 |
| 25 | Trappe | PA | 27 | 15 | 2 | 8,470 |
Frequently Asked Questions
What city has the worst tap water in Pennsylvania?
Based on 2026 data, Brownstown, PA 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.
