Water Quality in Defiance, MO: 38 Violations — Grade D
Grade D · Score 53/100 · 1 water system · Updated 2026-05-03
Defiance's water has significant violations. Water testing and filtration are recommended.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
EPA monitoring has flagged 38 reportable events for water systems in Defiance, MO.
Water Quality by ZIP Code in Defiance
Water quality varies across Defiance's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 63341 | D | 53 | 38 | 22 | View report → |
Violation Trend
EPA violations recorded for water systems serving Defiance.
Water Quality Overview
Defiance, Missouri receives a water quality grade of D with an overall score of 53 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 1 water system serving Defiance have accumulated 38 EPA violations, including 22 health-based violations. These violations are tracked across 1 ZIP codes serving approximately 110 people.
What Grade D Means
A grade of D indicates significant compliance issues. Defiance's water systems have accumulated violations that suggest ongoing water quality challenges. Residents should check their specific ZIP code report and consider water testing or filtration.
Lead Levels
The average 90th percentile lead level across Defiance water systems is 0.0021 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
Radon Risk
Defiance is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Defiance
Defiance is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 110 people across 1 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 Defiance. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Defiance
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
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 Defiance Water Systems
The following contaminants have been detected or caused violations across Defiance's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Gross Beta | Radionuclides | 50 pCi/L | 17 | 1 | Yes |
| Lead and Copper Rule | Treatment Technique | N/A | 12 | 1 | No |
| Stage 2 DBP Rule | Treatment Technique | N/A | 1 | 1 | No |
| Surface Water Treatment 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 Defiance:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2022 | 4 | 4 |
| 2023 | 6 | 6 |
| 2024 | 4 | 4 |
| 2025 | 1 | 1 |
Violations have decreased from 4 in 2022 to 1 in 2025, indicating improving compliance.
EPA Enforcement History
The EPA and state regulators have taken 10 enforcement actions against water systems serving Defiance. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-03 | State Filed Judgment |
| 2025-09-03 | State Informal Enforcement |
| 2025-09-01 | State Order Extension |
| 2025-08-14 | State Informal Action |
| 2025-08-14 | State Order Extension |
| 2025-06-11 | State Order Extension |
| 2025-05-19 | State Filed Judgment |
| 2025-05-19 | State Informal Enforcement |
| 2025-04-10 | State Order Extension |
| 2025-03-13 | State Filed Judgment |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-03.
Defiance vs. Nearby Missouri Cities
How Defiance's water quality compares to similar cities in Missouri:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Defiance | D | 38 | 1 | 110 |
| Catawissa | C | 0 | 1 | 110 |
| Lonedell | C | 0 | 1 | 110 |
| New Melle | D | 0 | 1 | 110 |
Common Questions About Defiance Water
These are the most common questions residents search for about water quality in Defiance, Missouri:
Is Defiance water hard or soft? Water hardness varies by source. Defiance's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink Defiance tap water? Defiance's water receives a grade of D (53/100). There are 22 health-based violations — consider filtration.
What is the best water filter for Defiance? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Defiance vs. Missouri Average
Understanding how Defiance compares to the broader Missouri 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 Defiance.
ZIP Codes in Defiance
Defiance spans 1 ZIP code. The ZIP with the lowest water quality score is 63341. Each ZIP code has its own water quality profile based on the specific water system serving that area. 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
Updated daily.