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Community Water System · PWS DE0000663

Wilmington Water Department

Wilmington, Delaware 19801 - drinking water served from surface water sources to 107,976 people, tracked in EPA SDWIS and UCMR5.

107,976
People served
30
EPA violations
13
Health-based
6 PFAS
UCMR5 result

The verdict

EPA records 30 drinking-water violations at Wilmington Water Department, 43% of them health-based - above the Delaware per-system average, and UCMR5 testing detected 6 PFAS compounds.

30
Total EPA violations on record
43%
Health-based (MCL / treatment failure)
107,976
People served by this system
6
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Wilmington Water Department

Wilmington Water Department is a local-owned community water system that delivers drinking water to 107,976 residents in Wilmington, Delaware (New Castle County) through 37,915 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 30 total violations for this system , of which 13 (43%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 13 monitoring and reporting violations are on file. The most recent violation on record dates to 2023.

The most frequently cited contaminant at this system is Surface Water Treatment Rule, recorded in 7 violations (TT, health-based). Under EPA's UCMR5 PFAS monitoring program, 6 PFAS compounds were detected in samples collected from this system, with a maximum reported concentration of 32.2 ppt (parts per trillion). PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.

Across Delaware, EPA tracks 460 public water systems serving 1,083,630 people, with 9,105 cumulative violations and 4,582 health-based violations on record. About 75% of systems in the state carry at least one violation, and state-wide the average per system is 19.8 violations. Statewide, 25 of 35 UCMR5-tested systems have reported PFAS detections (71.4%).

Wilmington Water Department's 30 violations sit above the Delaware average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

PFAS Detected

6 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

Population Served
107,976
Total Violations
30
Health-Based Violations
13
Water Source
Surface Water

System Details

System Type
Community
Owner Type
Local
Connections
37,915
County
New Castle
School/Daycare
No
MCL Violations
4
Monitoring Violations
13
Treatment Tech Violations
9

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Surface Water Treatment Rule TT 7 2004
Cryptosporidium MR 4 2015
Coliform (TCR) MCL 4 2013
Long Term 2 Enhanced Surface Water Treatment Rule MR 4 2015
Consumer Confidence Rule Other 3 2015
Revised Total Coliform Rule MON 3 2023
Coliform (TCR) MR 2 2001
Long Term 2 Enhanced Surface Water Treatment Rule TT 2 2017

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 40 of 232 samples detected PFAS.

Contaminant Date Result MRL Status
NMeFOSAA 8/9/2023 <6.00 ppt 6.00 ppt Not Detected
PFUnA 8/9/2023 <2.00 ppt 2.00 ppt Not Detected
PFHxA 8/9/2023 7.70 ppt 3.00 ppt Detected
PFDoA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFDA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFOA 8/9/2023 6.80 ppt 4.00 ppt Detected
11Cl-PF3OUdS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFOS 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFBS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFTA 8/9/2023 <8.00 ppt 8.00 ppt Not Detected
PFHxS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
9Cl-PF3ONS 8/9/2023 <2.00 ppt 2.00 ppt Not Detected
NEtFOSAA 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFTrDA 8/9/2023 <7.00 ppt 7.00 ppt Not Detected
6:2 FTS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
ADONA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFNA 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFBA 8/9/2023 10.20 ppt 5.00 ppt Detected
PFHpA 8/9/2023 3.70 ppt 3.00 ppt Detected
4:2 FTS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
8:2 FTS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFMPA 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFMBA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFEESA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
NFDHA 8/9/2023 <20.00 ppt 20.00 ppt Not Detected
PFPeS 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFHpS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFPeA 8/9/2023 8.20 ppt 3.00 ppt Detected
PFDA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFOA 8/9/2023 6.70 ppt 4.00 ppt Detected
PFOS 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFNA 8/9/2023 <4.00 ppt 4.00 ppt Not Detected
PFHxS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFHpA 8/9/2023 4.00 ppt 3.00 ppt Detected
PFBS 8/9/2023 3.30 ppt 3.00 ppt Detected
NMeFOSAA 8/9/2023 <6.00 ppt 6.00 ppt Not Detected
NEtFOSAA 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFDoA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFTA 8/9/2023 <8.00 ppt 8.00 ppt Not Detected
6:2 FTS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
PFTrDA 8/9/2023 <7.00 ppt 7.00 ppt Not Detected
PFHxA 8/9/2023 7.70 ppt 3.00 ppt Detected
PFUnA 8/9/2023 <2.00 ppt 2.00 ppt Not Detected
11Cl-PF3OUdS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected
9Cl-PF3ONS 8/9/2023 <2.00 ppt 2.00 ppt Not Detected
ADONA 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
PFBA 8/9/2023 10.50 ppt 5.00 ppt Detected
4:2 FTS 8/9/2023 <3.00 ppt 3.00 ppt Not Detected
8:2 FTS 8/9/2023 <5.00 ppt 5.00 ppt Not Detected

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Wilmington Water Department.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID DE0000663 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Delaware Drinking Water Authority

Delaware's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find DE regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2023 Revised Total Coliform Rule MON 3 SDWIS / DE0000663 / 8000
2017 Long Term 2 Enhanced Surface Water Treatment Rule TT 2 SDWIS / DE0000663 / 0800
2015 Cryptosporidium MR 4 SDWIS / DE0000663 / 3015
2015 Long Term 2 Enhanced Surface Water Treatment Rule MR 4 SDWIS / DE0000663 / 0800
2015 Consumer Confidence Rule Other 3 SDWIS / DE0000663 / 7000
2013 Coliform (TCR) MCL 4 SDWIS / DE0000663 / 3100
2004 Surface Water Treatment Rule TT 7 SDWIS / DE0000663 / 0200
2001 Coliform (TCR) MR 2 SDWIS / DE0000663 / 3100

How Wilmington Water Department Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Wilmington Water Department Delaware avg Federal benchmark
Total violations 30 19.8 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 13 10 Indicates a contaminant exceeded a federal MCL
PFAS detection 6 compounds 71.4% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 107,976 2,356 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 460 regulated public water systems in Delaware.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Wilmington Water Department water safe to drink? ▼
Wilmington Water Department (PWS ID: DE0000663) has 30 recorded violations in the EPA SDWIS database. PFAS contamination has been detected in UCMR5 testing, with 6 PFAS compounds found. This system serves 107,976 people using Surface Water sources.
How many people does Wilmington Water Department serve? ▼
Wilmington Water Department serves 107,976 people in Wilmington, Delaware. It is a Local-owned system using Surface Water water sources with 37,915 service connections.
What type of violations does Wilmington Water Department have? ▼
Wilmington Water Department has 30 total violations: 13 health-based violations (MCL exceedances or treatment failures), 13 monitoring/reporting violations, and 9 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Wilmington Water Department water? ▼
Yes. UCMR5 testing detected 6 PFAS compounds in Wilmington Water Department's water supply: PFHxA, PFOA, PFBA, PFHpA, PFPeA, and others. PFAS are persistent "forever chemicals" that do not break down in the environment.
What water source does Wilmington Water Department use? ▼
Wilmington Water Department uses Surface Water as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. PFAS data from EPA UCMR5 monitoring program (2023-2025). This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.