Water Quality in Mason City, IL: 1 Violation — Grade C
Grade C · Score 60/100 · 1 water system · Updated 2026-05-03
Mason City'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
Mason City in IL has 1 EPA water violation documented — the compliance history below covers what was flagged and which local systems are associated with each finding.
Water Quality by ZIP Code in Mason City
Water quality varies across Mason City's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 62664 | C | 60 | 1 | 0 | View report → |
Water Quality Overview
Mason City, Illinois receives a water quality grade of C with an overall score of 60 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 1 water system serving Mason City have accumulated 1 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 2,558 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Mason City'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
Lead testing data for Mason City is currently being collected. The EPA requires all community water systems to test for lead under the Lead and Copper Rule.
With 87% of homes built before 1986, Mason City 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
Mason City 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 Mason City
Mason City is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 2,558 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 2 enforcement actions against water systems serving Mason City. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Mason City
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 Mason City Water Systems
The following contaminants have been detected or caused violations across Mason City's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 2 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.
EPA Enforcement History
The EPA and state regulators have taken 2 enforcement actions against water systems serving Mason City. Recent actions:
| Date | Action Type |
|---|---|
| 2025-07-03 | State Informal Action |
| 2025-07-03 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-07-03.
Mason City vs. Nearby Illinois Cities
How Mason City's water quality compares to similar cities in Illinois:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Mason City | C | 1 | 1 | 2,558 |
| Galva | C | 1 | 2 | 2,529 |
| Kenilworth | B | 1 | 1 | 2,514 |
| Carthage | C | 3 | 1 | 2,510 |
Common Questions About Mason City Water
These are the most common questions residents search for about water quality in Mason City, Illinois:
Is Mason City water hard or soft? Water hardness varies by source. Mason City's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink Mason City tap water? Mason City's water receives a grade of C (60/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Mason City? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Mason City vs. Illinois Average
Understanding how Mason City compares to the broader Illinois 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 Mason City.
ZIP Codes in Mason City
Mason City spans 1 ZIP code. The ZIP with the lowest water quality score is 62664. 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.