Water Quality in Delaware, OK: 122 Violations Recorded for Mapped Water Systems
4 water systems · 1 directly mapped ZIP records
Available EPA records report 122 violations across 1 directly mapped ZIP records with known counts for Delaware. This is compliance evidence, not a property-level tap-water verdict.
Data: EPA Safe Drinking Water Information System (SDWIS)
Water Quality by ZIP Code in Delaware
This table shows typed EPA water evidence only. Missing violation counts are displayed as N/A, not zero.
| ZIP Code | Violations | Health | |
|---|---|---|---|
| 74027 | 122 | 49 | View report → |
Violation Trend
EPA violations recorded for water systems serving Delaware.
| Year | Total violations | Health-based |
|---|---|---|
| 2021 | 3 | 3 |
| 2022 | 8 | 8 |
| 2023 | 9 | 9 |
| 2024 | 8 | 8 |
| 2025 | 2 | 2 |
Water Quality Overview
Delaware, Oklahoma has directly mapped EPA water-system data for 1 ZIP codes. This page reports typed compliance facts and does not relabel the multi-source Home Safety Score as a drinking-water grade.
The available EPA records report 122 violations, including 49 health-based violations across 1 directly mapped ZIP record with reported counts.
Lead Levels
The average of the reported 90th-percentile lead results across the ZIP codes of Delaware is 0.0021 mg/L; the EPA action level of 0.015 mg/L applies to a water system's own 90th-percentile result and is not a safety threshold (EPA's health goal for lead is zero). No exceedances appear among the 1 ZIP records with known lead status.
With 57% of homes built before 1986, Delaware 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.
Water Systems Serving Delaware
Delaware is served by 4 community water systems regulated under the Safe Drinking Water Act. About 848 people live in the area (1 ZIP code, Census); this is not the systems' reported service population.
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
EPA records list 10 enforcement actions against water systems serving Delaware. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Delaware
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels and violation history
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
Contaminants Detected in Delaware Water Systems
The following contaminants have been detected or caused violations across Delaware's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 0.06 mg/L | 57 | 1 | Yes |
| Lead and Copper Rule | Treatment Technique | N/A | 23 | 1 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 17 | 1 | Yes |
| Stage 1 DBP Rule | Treatment Technique | N/A | 17 | 1 | No |
| Stage 2 DBP Rule | Treatment Technique | N/A | 4 | 1 | Yes |
| Surface Water Treatment Rule | Treatment Technique | N/A | 4 | 1 | No |
The standard column shows the EPA Maximum Contaminant Level (MCL) except for lead and copper, whose value is an action level that triggers corrective steps and is not an MCL. Health-based violations are MCL, MRDL and treatment-technique violations.
Violation Trend Over Time
Year-by-year EPA violations recorded for water systems serving Delaware:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 3 | 3 |
| 2022 | 8 | 8 |
| 2023 | 9 | 9 |
| 2024 | 8 | 8 |
| 2025 | 2 | 2 |
Violations have decreased from 3 in 2021 to 2 in 2025, indicating improving compliance.
EPA Enforcement History
The EPA and state regulators have taken 9 enforcement actions against water systems serving Delaware. Recent actions:
| Date | Action Type |
|---|---|
| 2026-02-19 | State Informal Action |
| 2026-02-19 | State Informal Enforcement |
| 2026-01-07 | State Order Extension |
| 2025-09-18 | State Order Extension |
| 2025-09-10 | State Order Extension |
| 2025-09-09 | State Informal Action |
| 2025-09-03 | State Order Extension |
| 2025-08-13 | State Informal Action |
| 2025-08-13 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2026-02-19.
Delaware vs. Nearby Oklahoma Cities
How Delaware's water quality compares to similar cities in Oklahoma:
| City | Direct EPA ZIPs | Violations | Systems | Population |
|---|---|---|---|---|
| Delaware | 1 | 122 | 4 | 848 |
| Osage | 0 | N/A | 0 | 853 |
| Mulhall | 1 | 13 | 5 | 857 |
| Ketchum | 1 | 101 | 5 | 833 |
Common Questions About Delaware Water
These are the most common questions residents search for about water quality in Delaware, Oklahoma:
Is Delaware water hard or soft? Water hardness varies by source. Delaware's 4 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Delaware tap water? City-level EPA records cannot determine safety at a specific tap. The measured subset contains 49 health-based violations; check the affected utility record and consider certified testing.
What is the best water filter for Delaware? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Delaware vs. Oklahoma Average
Understanding how Delaware compares to the broader Oklahoma 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 Delaware.
ZIP Codes in Delaware
Delaware spans 1 ZIP code. EPA water-system coverage is available for 1 directly mapped ZIP code. 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
Source reporting periods vary. See each cited source for its publication schedule.