Delaware Water Quality Report: 155 Violations Across 97 ZIPs
167 water systems · 97 ZIP codes · 155 violations · Updated 2026-05-31
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified: 2026-05-31
City Water Quality Map: Delaware
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Violation Trend
EPA violations across all water systems in Delaware.
Cities with Most Violations in Delaware
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Newark | B | 55 | 5 | 305,797 | Details → |
| 2 | Wilmington | B | 26 | 2 | 208,471 | Details → |
| 3 | Dover | A | 15 | 5 | 202,583 | Details → |
| 4 | Smyrna | A | 7 | 5 | 28,611 | Details → |
| 5 | Georgetown | A | 4 | 5 | 8,995 | Details → |
| 6 | Harrington | A | 4 | 5 | 3,839 | Details → |
| 7 | Viola | A | 4 | 1 | 50 | Details → |
| 8 | Millville | A | 3 | 2 | 51,115 | Details → |
| 9 | Fenwick Island | B | 3 | 4 | 12,264 | Details → |
| 10 | Selbyville | B | 3 | 4 | 5,811 | Details → |
Cities with Best Water Quality in Delaware
Most Common Contaminants in Delaware
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Surface Water Treatment Rule | Treatment Technique | 74 | 26 | No |
| Stage 1 DBP Rule | Treatment Technique | 29 | 24 | No |
| Contaminant 1032 | Other | 5 | 5 | Yes |
| Lead and Copper Rule | Treatment Technique | 1 | 1 | No |
| Lead | Inorganic | 1 | 1 | Yes |
| Contaminant 0700 | Other | 1 | 1 | No |
Water Quality Overview
Delaware has 167 community water systems serving approximately 1,220,327 people across 97 ZIP codes. These systems have accumulated 155 EPA violations, including 14 health-based violations.
Health-based violations account for 9% of all violations in Delaware. These violations indicate contaminant levels that may pose direct risks to human health, as opposed to monitoring or reporting failures.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 14 | 9.0% |
| Monitoring/Reporting | 141 | 91.0% |
| Total | 155 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report — these do not necessarily mean unsafe water, but they mean the water was not properly verified.
Cities with Most Violations
The following cities in Delaware have the highest number of EPA violations:
| Rank | City | Grade | Violations | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Newark | B | 55 | 5 | 305,797 |
| 2 | Wilmington | B | 26 | 2 | 208,471 |
| 3 | Dover | A | 15 | 5 | 202,583 |
| 4 | Smyrna | A | 7 | 5 | 28,611 |
| 5 | Georgetown | A | 4 | 5 | 8,995 |
| 6 | Harrington | A | 4 | 5 | 3,839 |
| 7 | Viola | A | 4 | 1 | 50 |
| 8 | Millville | A | 3 | 2 | 51,115 |
| 9 | Fenwick Island | B | 3 | 4 | 12,264 |
| 10 | Selbyville | B | 3 | 4 | 5,811 |
Violation counts are cumulative across all water systems serving each city. Higher counts may reflect larger systems with more monitoring requirements, not necessarily worse water quality.
Cities with Best Water Quality
These Delaware cities maintain Grade A water with zero violations:
| Rank | City | Grade | Score | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Dover Afb | A | 99/100 | 1 | 11,000 |
| 2 | Bridgeville | A | 95/100 | 4 | 8,152 |
| 3 | Delmar | A | 95/100 | 4 | 2,756 |
| 4 | Frankford | A | 90/100 | 5 | 32,216 |
| 5 | Clayton | A | 87/100 | 1 | 7,014 |
| 6 | Milford | A | 85/100 | 4 | 13,907 |
| 7 | Frederica | A | 85/100 | 2 | 1,811 |
Violation Trend Over Time
Year-by-year EPA violations recorded across all water systems in Delaware:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2022 | 2 | 2 |
| 2023 | 15 | 15 |
| 2024 | 4 | 4 |
| 2025 | 2 | 2 |
Most Common Contaminants
The following contaminants have caused the most violations across Delaware water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Surface Water Treatment Rule | Treatment Technique | 74 | 26 | No |
| Stage 1 DBP Rule | Treatment Technique | 29 | 24 | No |
| Lead and Copper Rule | Treatment Technique | 1 | 1 | No |
| Lead | Inorganic | 1 | 1 | Yes |
How to Check Your Water in Delaware
Enter your ZIP code on ZipCheckup for detailed water system data including contaminant levels, violation history, and safety scores
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400)
Consider filtration — NSF-certified filters can address specific contaminants found in your area
EPA Enforcement
The EPA and state regulators have taken 316 enforcement actions against water systems in Delaware. Enforcement actions range from compliance assistance to formal orders and penalties.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Updated daily.
What are EPA violations?
Health-based violations mean a contaminant was detected above the EPA's Maximum Contaminant Level (MCL) — the legal limit designed to protect human health. Delaware has 14 such violations across its water systems. Not all violations cause illness, but repeated exceedances increase risk, especially for children and immunocompromised individuals.
Understanding water quality grades
ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grade A means few or no violations; Grade F indicates persistent or serious issues. Grades are calculated per ZIP code and aggregated at the city, county, and state level.
Wondering about your tap water?
Water quality varies by ZIP code. Enter yours to see contaminant data, violations, and filtration recommendations specific to your area.
Check Your ZIP Code Water Quality →Frequently Asked Questions
Is the tap water safe to drink in Delaware?
Delaware has 167 community water systems with 155 recorded EPA violations, including 14 health-based. Water quality varies by city and ZIP code — check your specific location for detailed results.
How many water violations does Delaware have?
Delaware has 155 total EPA violations across 97 ZIP codes. 14 are health-based violations that indicate contaminant levels potentially harmful to human health. The remainder are monitoring or reporting violations.
Which city in Delaware has the worst water quality?
Newark, DE has the most EPA violations among major cities in Delaware with 55 recorded violations. Check individual ZIP codes for the most accurate picture of your local water quality.
Which city in Delaware has the best water quality?
Dover Afb, DE ranks among the best for water quality in Delaware with a grade of A. Multiple cities in Delaware maintain strong EPA compliance records.
What contaminants are found in Delaware drinking water?
Delaware water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. The most common violations vary by region — check your ZIP code for contaminant-specific data.