Water Quality in Defiance, OH: 18 Violations — Grade D
Grade D · Score 52/100 · 5 water systems · 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
Federal EPA data for Defiance, OH shows 18 water compliance events in the record — the table below identifies system names and violation types.
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 | |
|---|---|---|---|---|---|
| 43512 | D | 52 | 18 | 16 | View report → |
Violation Trend
EPA violations recorded for water systems serving Defiance.
Water Quality Overview
Defiance, Ohio receives a water quality grade of D with an overall score of 52 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Defiance have accumulated 18 EPA violations, including 16 health-based violations. These violations are tracked across 1 ZIP codes serving approximately 19,405 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 0.0025 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 78% of homes built before 1986, Defiance 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.
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 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 19,405 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 |
|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 0.06 mg/L | 16 | 1 | Yes |
| 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 |
|---|---|---|
| 2021 | 1 | 1 |
| 2022 | 14 | 14 |
Violations have increased from 1 in 2021 to 14 in 2022. This trend warrants monitoring.
EPA Enforcement History
The EPA and state regulators have taken 9 enforcement actions against water systems serving Defiance. Recent actions:
| Date | Action Type |
|---|---|
| 2025-06-24 | State Order Extension |
| 2024-11-01 | State Order Extension |
| 2024-07-31 | State Informal Action |
| 2023-01-18 | State Filed Suit |
| 2023-01-11 | State Order Extension |
| 2022-12-05 | State Informal Action |
| 2022-11-07 | State Informal Action |
| 2022-11-07 | State Informal Enforcement |
| 2022-10-13 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-06-24.
Defiance vs. Nearby Ohio Cities
How Defiance's water quality compares to similar cities in Ohio:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Defiance | D | 18 | 5 | 19,405 |
| Springboro | C | 0 | 1 | 19,263 |
| Pickerington | C | 0 | 1 | 19,141 |
| Curtice | C | 0 | 1 | 19,950 |
Common Questions About Defiance Water
These are the most common questions residents search for about water quality in Defiance, Ohio:
Is Defiance water hard or soft? Water hardness varies by source. Defiance's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Defiance tap water? Defiance's water receives a grade of D (52/100). There are 16 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. Ohio Average
Understanding how Defiance compares to the broader Ohio 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 43512. 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.