Wilmington Water Department
EPA ID: DE0000663 · 107,976 people served · 29 ZIP codes
A total of 1 EPA violation spanning the past five monitoring years sit on Wilmington Water Department's record — every finding has been officially cleared, and the supplier now holds current compliance status for its service population of approximately 107,976 people, with no outstanding enforcement of any kind.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Wilmington Water Department Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The Wilmington Water Department serves a community with a median household income of $85,988 and an estimated 296,060 residents across its service area. Approximately 80% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Wilmington Water Department's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in New Castle County, Delaware rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 89th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How Wilmington Water Department compares to EPA limits
What This Means For You
Consumer Confidence Report Rule at 1 mg/L exceeds the EPA maximum of mg/L.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 136 detections recorded. 29 exceed federal EPA limits (4 ppt for PFOA/PFOS).
Comparable Water Systems
Similar-sized systems in Delaware
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
WILMINGTON WATER DEPARTMENT (EPA ID: DE0000663) is a community water system in Delaware that serves approximately 107,976 people from surface water sources.
This system provides water to 29 ZIP codes across 4 communities.
Average Home Safety Score: B (79/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| August 1, 2023 | Consumer Confidence Report Rule | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Consumer Confidence Report Rule | Reporting Failure | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 19801 | 0.0022 mg/L | No | N/A |
| 19802 | 0.0022 mg/L | No | N/A |
| 19803 | 0.0022 mg/L | No | N/A |
| 19804 | 0.0022 mg/L | No | N/A |
| 19805 | 0.0022 mg/L | No | N/A |
| 19806 | 0.0022 mg/L | No | N/A |
| 19807 | 0.0022 mg/L | No | N/A |
| 19809 | 0.0022 mg/L | No | N/A |
| 19810 | 0.0022 mg/L | No | N/A |
| 19850 | 0.0022 mg/L | No | N/A |
| 19880 | 0.0022 mg/L | No | N/A |
| 19884 | 0.0022 mg/L | No | N/A |
| 19885 | 0.0022 mg/L | No | N/A |
| 19886 | 0.0022 mg/L | No | N/A |
| 19887 | 0.0022 mg/L | No | N/A |
| 19890 | 0.0022 mg/L | No | N/A |
| 19891 | 0.0022 mg/L | No | N/A |
| 19892 | 0.0022 mg/L | No | N/A |
| 19893 | 0.0022 mg/L | No | N/A |
| 19894 | 0.0022 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 11 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 18 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 19703 — Claymont
- 19720 — New Castle
- 19732 — Rockland
- 19801 — Wilmington
- 19802 — Wilmington
- 19803 — Wilmington
- 19804 — Wilmington
- 19805 — Wilmington
- 19806 — Wilmington
- 19807 — Wilmington
- 19808 — Wilmington
- 19809 — Wilmington
- 19810 — Wilmington
- 19850 — Wilmington
- 19880 — Wilmington
- 19884 — Wilmington
- 19885 — Wilmington
- 19886 — Wilmington
- 19887 — Wilmington
- 19890 — Wilmington
- 19891 — Wilmington
- 19892 — Wilmington
- 19893 — Wilmington
- 19894 — Wilmington
- 19895 — Wilmington
- 19896 — Wilmington
- 19897 — Wilmington
- 19898 — Wilmington
- 19899 — Wilmington
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Wilmington Water Department (DE0000663) on EPA.gov.
Frequently Asked Questions
Is Wilmington Water Department water safe to drink?
Wilmington Water Department has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does Wilmington Water Department serve?
Wilmington Water Department serves approximately 107,976 people across 29 ZIP codes in Delaware.
Where does Wilmington Water Department get its water?
The primary water source is surface water.
Contact Your Water Utility
Public-record contact information for the water utility serving this system. Use these channels to request water quality reports, ask about service, or report issues directly.
Contact information from CITY OF WILMINGTON Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility, does not act as its agent, and does not provide customer support for it. Contact details shown are public-record information from CCR filings. For service issues, contact the utility directly using the information above.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: CITY OF WILMINGTON Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
The Division of Public Health, in conjunction with the Department of Natural Resources and Environmental Control (DNREC), has conducted source water assessments for nearly all community water systems in the state. The assessment may also be viewed at this website: www.delawaresourcewater.org.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Treatment classification and chemical list sourced from CITY OF WILMINGTON Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
PFAS Substances Detected in This System
This water system's Consumer Confidence Report disclosed the following PFAS compounds. Levels are from the utility's most recent reporting cycle.
In April 2024, EPA finalized the first National Primary Drinking Water Regulation for six PFAS. Public water systems have until 2029 to comply. EPA — PFAS regulation overview →
Source: Consumer Confidence Report disclosed by CITY OF WILMINGTON.
ZipCheckup is not affiliated with this water utility. PFAS detection data is sourced from public Consumer Confidence Reports filed by the utility itself.
On October 15, 2024, the City of Wilmington released the initial Water Service Line Inventory. In accordance with the United States Environmental Protection Agency’s (EPA) revised Lead and Copper Rule (LCRR), the City of Wilmington recently submitted to the state of Delaware an initial inventory of the City’s service lines that connect our water mains to our customers’ homes and businesses.
Lead Service Line Replacement Tracker
This water utility's lead service line (LSL) replacement program is tracked from public Consumer Confidence Report filings. Email signup notifies subscribers when the utility files an updated replacement plan or progress milestone.
CITY OF WILMINGTON
ZipCheckup is not affiliated with this water utility. LSL replacement-program data is sourced from public CCR filings published by the utility. Subscription notifications are based on automated parsing of subsequent CCR releases.
Learn more about Lead and Copper Rule replacement requirements →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Aesthetic water quality
These measurements describe the look, taste, and feel of the water this utility delivers. They are not contaminant violations — they sit alongside federal Secondary Maximum Contaminant Levels (SMCLs) which the EPA publishes as non-enforceable guidance.
Aesthetic measurements from CITY OF WILMINGTON Consumer Confidence Report.
Aesthetic measurements are reported by the utility from its annual sampling. EPA Secondary MCLs are advisory thresholds — values outside them indicate aesthetic concerns such as taste or appearance, not health violations. Federal contaminant testing is shown in the sections above.
Hard water detected in CITY OF WILMINGTON
Your utility reported water hardness of 128 ppm CaCO₃ (7.5 grains per gallon) in its most recent Consumer Confidence Report. This is in the moderately hard range and may cause scale buildup, reduced appliance lifespan, and dry skin or hair.
There are three common approaches to treating hard water: salt-based ion-exchange softeners (most effective, require salt refills), salt-free conditioners (lower maintenance, scale prevention only), and reverse osmosis at the kitchen sink (cooking and drinking water only). Aquasana, EcoWater, Pelican, and SpringWell are among the major US brands.
Paid Partner. ZipCheckup earns commission on Aquasana purchases. We do not test water or verify product effectiveness for specific hardness levels — manufacturer claims are theirs alone. Consult a certified water-quality professional for personalized advice.
Hardness data parsed from this utility's most recent Consumer Confidence Report. Severity bands per USGS hard water classification.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Wilmington Water Department (EPA ID: DE0000663) — request the latest Consumer Confidence Report or ask about specific contaminants.