Community Water System · PWS DE0000663
Wilmington Water Department
Operator location Wilmington, Delaware - 43% of 30 violations are health-based (upper-third health share (> 23%)); surface water source; 107,976 served per SDWIS.
- 107,976
- People served (this PWS)
- 30
- EPA violations (this PWS)
- 13
- Health-based (this PWS)
- 6 PFAS
- UCMR5 (this PWS)
Wilmington Water Department standing, mid SDWIS violation third
43% of 30 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 43% is upper-third health share (> 23%). UCMR5: upper-third PFAS panel (> 4 compounds). Population rank #440 of 29,740 among systems serving 500+.
The verdict
Wilmington Water Department lands in the middle third by violation volume (30), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (107,976; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 43% - most of this ledger is MCL or treatment-technique exceedance. UCMR5 detected 6 PFAS compounds (upper-third PFAS panel (> 4 compounds)).
- #440 of 29,740
- Population · /systems
- #2 of 117
- Population · DE
- 30
- Total EPA violations on record
- 43%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
6 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
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 |
Violation Count vs. the National Corpus
Wilmington Water Department has 30 recorded EPA violations, 42% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 57% carry more. 43% of this system's own violations are health-based (13 of 30), and it ranks #440 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
30 Lower than most fewer violations than 57% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
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 |
Health-based violations on Wilmington Water Department
13 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for DE0000663.
Sources: EPA SDWIS
Nationwide peers
30 violations · 107,976 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Wilmington Water Department
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Delaware compares on the same EPA violation measures. Delaware systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.