Water Quality in Cincinnati, OH: 71 Violations — Grade C
Grade C · Score 66/100 · 5 water systems · Updated 2026-05-03
Cincinnati's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
SDWIS records for Cincinnati, OH show 71 EPA violations documented for the local water supply — these span the full range of reportable events from health-based exceedances to monitoring and reporting lapses registered with the federal program.
Water Quality Map: Cincinnati, OH
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Cincinnati
Water quality varies across Cincinnati's 71 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 45226 | C | 55 | 1 | 0 | View report → |
| 45202 | C | 60 | 1 | 0 | View report → |
| 45223 | C | 60 | 1 | 0 | View report → |
| 45227 | C | 60 | 1 | 0 | View report → |
| 45230 | C | 60 | 1 | 0 | View report → |
| 45231 | C | 60 | 1 | 0 | View report → |
| 45237 | C | 60 | 1 | 0 | View report → |
| 45239 | C | 60 | 1 | 0 | View report → |
| 45241 | C | 60 | 1 | 0 | View report → |
| 45244 | C | 60 | 1 | 0 | View report → |
| 45203 | C | 65 | 1 | 0 | View report → |
| 45204 | C | 65 | 1 | 0 | View report → |
| 45208 | C | 65 | 1 | 0 | View report → |
| 45215 | C | 65 | 1 | 0 | View report → |
| 45216 | C | 65 | 1 | 0 | View report → |
Water Quality Overview
Cincinnati, Ohio receives a water quality grade of C with an overall score of 66 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Cincinnati have accumulated 71 EPA violations (all monitoring/reporting type). These violations are tracked across 71 ZIP codes serving approximately 775,555 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Cincinnati's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Cincinnati water systems is 0.0020 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 79% of homes built before 1986, Cincinnati 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
Cincinnati is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Cincinnati
Cincinnati is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 775,555 people across 71 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 426 enforcement actions against water systems serving Cincinnati. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Cincinnati
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 Cincinnati Water Systems
The following contaminants have been detected or caused violations across Cincinnati's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Surface Water Treatment Rule | Treatment Technique | N/A | 71 | 71 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 5 enforcement actions against water systems serving Cincinnati. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-15 | State Order Extension |
| 2025-09-13 | State Order Extension |
| 2025-09-04 | State Informal Action |
| 2025-06-24 | State Order Extension |
| 2023-09-28 | State Informal Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-15.
Cincinnati vs. Nearby Ohio Cities
How Cincinnati's water quality compares to similar cities in Ohio:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Cincinnati | C | 71 | 5 | 775,555 |
| Camp Dennison | D | 0 | 1 | 750,200 |
| Mount Saint Joseph | D | 0 | 1 | 750,200 |
| Ross | D | 0 | 1 | 750,200 |
Water Quality by ZIP Code in Cincinnati
Water quality varies across Cincinnati's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 45226 | 55 | C | 1 | 0 |
| 45202 | 60 | C | 1 | 0 |
| 45223 | 60 | C | 1 | 0 |
| 45227 | 60 | C | 1 | 0 |
| 45230 | 60 | C | 1 | 0 |
| 45231 | 60 | C | 1 | 0 |
| 45237 | 60 | C | 1 | 0 |
| 45239 | 60 | C | 1 | 0 |
| 45241 | 60 | C | 1 | 0 |
| 45244 | 60 | C | 1 | 0 |
| 45245 | 83 | B | 1 | 0 |
| 45255 | 70 | B | 1 | 0 |
| 45252 | 70 | B | 1 | 0 |
| 45251 | 70 | B | 1 | 0 |
| 45249 | 70 | B | 1 | 0 |
Water quality scores in Cincinnati range from 55 to 83 — a spread of 28 points. This variation means your specific ZIP code matters significantly.
Common Questions About Cincinnati Water
These are the most common questions residents search for about water quality in Cincinnati, Ohio:
Is Cincinnati water hard or soft? Water hardness varies by source. Cincinnati's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Cincinnati tap water? Cincinnati's water receives a grade of C (66/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Cincinnati? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Cincinnati vs. Ohio Average
Understanding how Cincinnati 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 Cincinnati.
ZIP Codes in Cincinnati
Cincinnati spans 71 ZIP codes. The ZIP with the lowest water quality score is 45201. 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.