Water Quality in Wilmington, DE: 26 Violations — Grade B
Grade B · Score 80/100 · 2 water systems · Updated 2026-05-03
Wilmington's water is mostly safe. Minor violations exist but are primarily monitoring-related.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Water systems in Wilmington, DE have accumulated 26 EPA violations across the full compliance record — a dataset that captures reportable health-based exceedances, monitoring lapses, and enforcement actions filed with the federal Safe Drinking Water Information System.
Water Quality Map: Wilmington, DE
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Wilmington
Water quality varies across Wilmington's 26 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 19804 | C | 68 | 1 | 0 | View report → |
| 19801 | B | 73 | 1 | 0 | View report → |
| 19802 | B | 73 | 1 | 0 | View report → |
| 19803 | B | 73 | 1 | 0 | View report → |
| 19805 | B | 73 | 1 | 0 | View report → |
| 19808 | B | 73 | 1 | 0 | View report → |
| 19810 | B | 73 | 1 | 0 | View report → |
| 19806 | B | 78 | 1 | 0 | View report → |
| 19809 | B | 78 | 1 | 0 | View report → |
| 19850 | B | 83 | 1 | 0 | View report → |
| 19880 | B | 83 | 1 | 0 | View report → |
| 19884 | B | 83 | 1 | 0 | View report → |
| 19885 | B | 83 | 1 | 0 | View report → |
| 19886 | B | 83 | 1 | 0 | View report → |
| 19887 | B | 83 | 1 | 0 | View report → |
Water Quality Overview
Wilmington, Delaware receives a water quality grade of B with an overall score of 80 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 2 water systems serving Wilmington have accumulated 26 EPA violations (all monitoring/reporting type). These violations are tracked across 26 ZIP codes serving approximately 208,471 people.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, Wilmington's water systems meet the vast majority of federal requirements. Minor violations may exist but typically relate to monitoring or reporting rather than health-based standards.
Lead Levels
The average 90th percentile lead level across Wilmington water systems is 0.0022 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 83% of homes built before 1986, Wilmington has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Wilmington is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Wilmington
Wilmington is served by 2 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 208,471 people across 26 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 78 enforcement actions against water systems serving Wilmington. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Wilmington
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
EPA Enforcement History
The EPA and state regulators have taken 3 enforcement actions against water systems serving Wilmington. Recent actions:
| Date | Action Type |
|---|---|
| 2023-10-09 | State Order Extension |
| 2023-09-10 | State Filed Judgment |
| 2023-09-10 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2023-10-09.
Wilmington vs. Nearby Delaware Cities
How Wilmington's water quality compares to similar cities in Delaware:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Wilmington | B | 26 | 2 | 208,471 |
| Dover | A | 15 | 5 | 202,583 |
| Newark | B | 55 | 5 | 305,797 |
| Claymont | C | 0 | 1 | 107,976 |
Water Quality by ZIP Code in Wilmington
Water quality varies across Wilmington's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 19804 | 68 | C | 1 | 0 |
| 19801 | 73 | B | 1 | 0 |
| 19802 | 73 | B | 1 | 0 |
| 19803 | 73 | B | 1 | 0 |
| 19805 | 73 | B | 1 | 0 |
| 19808 | 73 | B | 1 | 0 |
| 19810 | 73 | B | 1 | 0 |
| 19806 | 78 | B | 1 | 0 |
| 19809 | 78 | B | 1 | 0 |
| 19850 | 83 | B | 1 | 0 |
| 19807 | 90 | A | 1 | 0 |
| 19899 | 83 | B | 1 | 0 |
| 19898 | 83 | B | 1 | 0 |
| 19897 | 83 | B | 1 | 0 |
| 19896 | 83 | B | 1 | 0 |
Water quality scores in Wilmington range from 68 to 90 — a spread of 22 points. This variation means your specific ZIP code matters significantly.
Common Questions About Wilmington Water
These are the most common questions residents search for about water quality in Wilmington, Delaware:
Is Wilmington water hard or soft? Water hardness varies by source. Wilmington's 2 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Wilmington tap water? Wilmington's water receives a grade of B (80/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Wilmington? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Wilmington vs. Delaware Average
Understanding how Wilmington compares to the broader Delaware average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Wilmington.
ZIP Codes in Wilmington
Wilmington spans 26 ZIP codes. The ZIP with the lowest water quality score is 19801. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.
Frequently Asked Questions
Your Water is Safe — Here's How to Keep It That Way
Grade B is excellent news. Here's what proactive homeowners do to maintain water quality:
Annual Water Testing
EPA recommends annual testing even with clean water. Home test kits: $20-$50. Catches changes before they become problems.
Maintenance Filtration
A basic carbon filter removes chlorine taste and catches emerging contaminants like PFAS that aren't yet fully regulated.
Plumbing Check
Even safe city water picks up lead from home pipes. If your home was built before 1986, a one-time pipe inspection is recommended.