We analyzed tap water quality data for hundreds of cities in Delaware 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EPA legal limits, many health experts — including the Environmental Working Group — argue that these legal limits are outdated and don't reflect current scientific understanding of safe exposure levels.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
Newark, Delaware
Newark has 17 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 Newark water report →Middletown, Delaware
Middletown has 16 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 Middletown water report →Wilmington, Delaware
Wilmington has 16 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 Wilmington water report →Smyrna, Delaware
Smyrna has 16 contaminants exceeding EWG health guidelines out of 26 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Smyrna water report →Dover, Delaware
Dover has 15 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 Dover water report →Dagsboro, Delaware
Dagsboro has 13 contaminants exceeding EWG health guidelines out of 22 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Dagsboro water report →Ocean View, Delaware
Ocean View 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 Ocean View water report →Springfield, Delaware
Springfield 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 Springfield water report →Lewes, Delaware
Lewes has 12 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 Lewes water report →Camden, Delaware
Camden 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 Camden water report →Rehoboth Beach, Delaware
Rehoboth Beach 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 Rehoboth Beach water report →Frankford, Delaware
Frankford 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 Frankford water report →Selbyville, Delaware
Selbyville 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 Selbyville water report →Millsboro, Delaware
Millsboro 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 Millsboro water report →Bridgeville, Delaware
Bridgeville 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 Bridgeville water report →Milton, Delaware
Milton has 10 contaminants exceeding EWG health guidelines out of 13 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Milton water report →Bethany Beach, Delaware
Bethany Beach has 9 contaminants exceeding EWG health guidelines out of 14 total detected, placing it among the most concerning water supplies analyzed.
See full Bethany Beach water report →New Castle, Delaware
New Castle has 9 contaminants exceeding EWG health guidelines out of 13 total detected, placing it among the most concerning water supplies analyzed.
See full New Castle water report →Greenwood, Delaware
Greenwood has 9 contaminants exceeding EWG health guidelines out of 12 total detected, placing it among the most concerning water supplies analyzed.
See full Greenwood water report →Hockessin, Delaware
Hockessin has 9 contaminants exceeding EWG health guidelines out of 9 total detected, placing it among the most concerning water supplies analyzed.
See full Hockessin water report →Milford, Delaware
Milford has 8 contaminants exceeding EWG health guidelines out of 13 total detected, placing it among the most concerning water supplies analyzed.
See full Milford water report →Seaford, Delaware
Seaford has 8 contaminants exceeding EWG health guidelines out of 13 total detected, placing it among the most concerning water supplies analyzed.
See full Seaford water report →Harrington, Delaware
Harrington has 8 contaminants exceeding EWG health guidelines out of 13 total detected, placing it among the most concerning water supplies analyzed.
See full Harrington water report →Long Neck, Delaware
Long Neck has 8 contaminants exceeding EWG health guidelines out of 12 total detected, placing it among the most concerning water supplies analyzed.
See full Long Neck water report →Laurel, Delaware
Laurel has 7 contaminants exceeding EWG health guidelines out of 13 total detected, placing it among the most concerning water supplies analyzed.
See full Laurel water report →What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Bromodichloromethane, Chloroform, Total trihalomethanes (TTHMs). 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, 278 contaminant readings exceed EWG health guidelines, but only 5 exceed EPA legal limits. This gap of 273 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 | Newark | DE | 41 | 17 | 0 | 301,000 |
| 2 | Middletown | DE | 42 | 16 | 0 | 17,700 |
| 3 | Wilmington | DE | 35 | 16 | 1 | 107,976 |
| 4 | Smyrna | DE | 26 | 16 | 1 | 11,813 |
| 5 | Dover | DE | 28 | 15 | 0 | 39,491 |
| 6 | Dagsboro | DE | 22 | 13 | 0 | 900 |
| 7 | Ocean View | DE | 20 | 12 | 0 | 2,073 |
| 8 | Springfield | DE | 20 | 12 | 0 | 126 |
| 9 | Lewes | DE | 15 | 12 | 1 | 3,000 |
| 10 | Camden | DE | 19 | 11 | 0 | 5,000 |
| 11 | Rehoboth Beach | DE | 18 | 11 | 0 | 2,400 |
| 12 | Frankford | DE | 18 | 11 | 1 | 1,000 |
| 13 | Selbyville | DE | 14 | 11 | 0 | 3,502 |
| 14 | Millsboro | DE | 15 | 10 | 0 | 6,863 |
| 15 | Bridgeville | DE | 14 | 10 | 0 | 0 |
| 16 | Milton | DE | 13 | 10 | 0 | 3,200 |
| 17 | Bethany Beach | DE | 14 | 9 | 0 | 1,000 |
| 18 | New Castle | DE | 13 | 9 | 0 | 5,364 |
| 19 | Greenwood | DE | 12 | 9 | 0 | 973 |
| 20 | Hockessin | DE | 9 | 9 | 1 | 60 |
| 21 | Milford | DE | 13 | 8 | 0 | 9,800 |
| 22 | Seaford | DE | 13 | 8 | 0 | 6,699 |
| 23 | Harrington | DE | 13 | 8 | 0 | 3,562 |
| 24 | Long Neck | DE | 12 | 8 | 0 | 5,500 |
| 25 | Laurel | DE | 13 | 7 | 0 | 3,984 |
Frequently Asked Questions
What city has the worst tap water in Delaware?
Based on 2026 data, Newark, DE 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.
