Water Quality in Duncan, OK: 34 Violations - Grade N/A
5 water systems · 1 directly mapped ZIP records
Available EPA records report 34 violations across 1 directly mapped ZIP records with known counts for Duncan. 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 Duncan
This table shows typed EPA water evidence only. Missing violation counts are displayed as N/A, not zero.
| ZIP Code | Violations | Health | |
|---|---|---|---|
| 73533 | 34 | 15 | View report → |
Violation Trend
EPA violations recorded for water systems serving Duncan.
| Year | Total violations | Health-based |
|---|---|---|
| 2021 | 3 | 3 |
| 2022 | 4 | 4 |
| 2023 | 2 | 2 |
| 2024 | 5 | 5 |
Water Quality Overview
Duncan, 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 34 violations, including 15 health-based violations across 1 directly mapped ZIP record with reported counts.
Lead Levels
The average 90th percentile lead level across Duncan water systems is 0.0014 mg/L - within EPA limits. No exceedances appear among the 1 ZIP records with known lead status.
With 77% of homes built before 1986, Duncan 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 Duncan
Duncan is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 27,935 people across 3 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 10 enforcement actions against water systems serving Duncan. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Duncan
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 Duncan Water Systems
The following contaminants have been detected or caused violations across Duncan's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 0.06 mg/L | 10 | 1 | Yes |
| Chlorite | Disinfection Byproducts | 1 mg/L | 6 | 1 | Yes |
| Revised Total Coliform Rule | Microbiological | N/A | 5 | 1 | No |
| Total Coliform | Microbiological | N/A | 3 | 1 | No |
| Stage 2 DBP Rule | Treatment Technique | N/A | 2 | 1 | Yes |
| Arsenic | Inorganic | 0.01 mg/L | 1 | 1 | No |
| Stage 1 DBP Rule | Treatment Technique | N/A | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
Violation Trend Over Time
Year-by-year EPA violations recorded for water systems serving Duncan:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 3 | 3 |
| 2022 | 4 | 4 |
| 2023 | 2 | 2 |
| 2024 | 5 | 5 |
Violations have increased from 3 in 2021 to 5 in 2024. This trend warrants monitoring.
EPA Enforcement History
The EPA and state regulators have taken 6 enforcement actions against water systems serving Duncan. Recent actions:
| Date | Action Type |
|---|---|
| 2026-03-10 | EPA Formal Action |
| 2026-02-24 | State Order Extension |
| 2026-02-19 | State Informal Action |
| 2026-02-19 | State Informal Enforcement |
| 2026-01-27 | State Informal Action |
| 2026-01-27 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2026-03-10.
Duncan vs. Nearby Oklahoma Cities
How Duncan's water quality compares to similar cities in Oklahoma:
| City | Direct EPA ZIPs | Violations | Systems | Population |
|---|---|---|---|---|
| Duncan | 1 | 34 | 5 | 27,935 |
| Mustang | 1 | 24 | 5 | 27,620 |
| Mcalester | 1 | 312 | 5 | 28,687 |
| Durant | 1 | 62 | 4 | 26,548 |
Common Questions About Duncan Water
These are the most common questions residents search for about water quality in Duncan, Oklahoma:
Is Duncan water hard or soft? Water hardness varies by source. Duncan's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Duncan tap water? City-level EPA records cannot determine safety at a specific tap. The measured subset contains 15 health-based violations; check the affected utility record and consider certified testing.
What is the best water filter for Duncan? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Duncan vs. Oklahoma Average
Understanding how Duncan 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 Duncan.
ZIP Codes in Duncan
Duncan spans 3 ZIP codes. 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.