Maricopa County Water Quality: 4,612 Violations (AZ)
63 water systems · 131 ZIP codes · Home Safety Score 66/100 (C) · 127 of 199 tracked ZIP records scored · Updated
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified:
Violation Trend
EPA violations across water systems in Maricopa County.
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Find the Right Filter →Water Quality Overview
Maricopa County has 63 community water systems across 131 directly mapped ZIP records. The systems report serving approximately 4,506,819 people. The available records contain 4,612 EPA violations, including 116 health-based violations.
Health-based violations account for 3% of all violations in Maricopa County. These violations indicate contaminant levels that may pose direct risks to human health.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 116 | 2.5% |
| Monitoring/Reporting | 4,496 | 97.5% |
| Total | 4,612 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report.
Cities with Most Violations
| Rank | City | Violations | Health-Based | ZIP Codes | Population |
|---|---|---|---|---|---|
| 1 | Gilbert | 1,182 | 5 | 6 | 272,707 |
| 2 | Mesa | 863 | 0 | 13 | 550,266 |
| 3 | Chandler | 683 | 6 | 6 | 297,943 |
| 4 | Surprise | 304 | 10 | 5 | 154,234 |
| 5 | Queen Creek | 215 | 0 | 1 | 87,201 |
| 6 | Higley | 174 | 0 | 1 | 0 |
| 7 | Phoenix | 166 | 49 | 43 | 1,454,993 |
| 8 | Goodyear | 148 | 5 | 2 | 103,149 |
| 9 | Buckeye | 144 | 4 | 2 | 112,401 |
| 10 | Glendale | 93 | 7 | 9 | 311,041 |
Violation Trend
Year-by-year EPA violations across water systems in Maricopa County:
| Year | Total | Health-Based |
|---|---|---|
| 2021 | 5 | 5 |
| 2022 | 20 | 20 |
| 2023 | 7 | 7 |
| 2024 | 163 | 163 |
| 2025 | 40 | 40 |
Most Common Contaminants
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Barium | Inorganic | 278 | 42 | Yes |
| Lead | Inorganic | 221 | 43 | Yes |
| E. coli | Microbiological | 199 | 103 | No |
| Chlorite | Disinfection Byproducts | 155 | 59 | No |
| Fecal Coliform | Microbiological | 128 | 76 | Yes |
| Revised Total Coliform Rule | Microbiological | 105 | 32 | No |
| Dichloroacetic Acid | Disinfection Byproducts | 99 | 34 | No |
| Stage 1 DBP Rule | Treatment Technique | 96 | 42 | Yes |
| PFOA | PFAS | 85 | 28 | No |
| PFNA | PFAS | 85 | 28 | No |
Water Data and the Home Safety Score
This page reports EPA water-system facts without converting the broader Home Safety Score into a drinking-water grade. The county Home Safety grade (C) is a separate multi-source index that also requires PFAS screening, radon, and annual air-quality evidence. Check each ZIP report for the versioned score and its component coverage.
Water Systems in Maricopa County
Maricopa County is served by 63 community water systems, averaging 0.3 systems per ZIP code. Each system is independently regulated and tested by the EPA. Larger systems serving more people typically have more extensive monitoring requirements.
Water systems in Maricopa County source water from a mix of surface water (rivers, reservoirs) and groundwater (wells, aquifers). Source type affects which contaminants are most likely to be detected.
How to Check Your Water in Maricopa County
Enter your ZIP code on ZipCheckup for detailed water-system data including contaminant levels and violation history; the Home Safety Score is shown separately with its model version
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400) can detect contaminants not covered by routine testing
Consider filtration — NSF-certified filters can address specific contaminants found in your area
Check for lead — homes built before 1986 should test for lead regardless of utility compliance
EPA Enforcement
The EPA and state regulators have taken 1,284 enforcement actions against water systems in Maricopa County. Enforcement actions range from compliance assistance and administrative orders to formal penalties. Systems under enforcement are required to remediate violations and may face ongoing monitoring requirements.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Source publication schedules vary. See the page source and verification fields for available timing evidence.
Water Quality by ZIP Code in Maricopa County
Water quality varies across Maricopa County's 131 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | City | Violations | Health | |
|---|---|---|---|---|
| 85298 | Gilbert | 278 | 4 | View → |
| 85249 | Chandler | 269 | 4 | View → |
| 85142 | Queen Creek | 215 | 0 | View → |
| 85212 | Mesa | 203 | 0 | View → |
| 85209 | Mesa | 200 | 0 | View → |
| 85206 | Mesa | 200 | 0 | View → |
| 85234 | Gilbert | 200 | 0 | View → |
| 85296 | Gilbert | 182 | 1 | View → |
| 85233 | Gilbert | 174 | 0 | View → |
| 85236 | Higley | 174 | 0 | View → |
| 85295 | Gilbert | 174 | 0 | View → |
| 85297 | Gilbert | 174 | 0 | View → |
| 85248 | Chandler | 94 | 2 | View → |
| 85395 | Goodyear | 91 | 3 | View → |
| 85225 | Chandler | 83 | 0 | View → |
| 85286 | Chandler | 83 | 0 | View → |
| 85340 | Litchfield Park | 79 | 7 | View → |
| 85224 | Chandler | 77 | 0 | View → |
| 85226 | Chandler | 77 | 0 | View → |
| 85378 | Surprise | 77 | 2 | View → |
What are EPA health violations?
Health-based violations mean a contaminant was detected above the EPA's Maximum Contaminant Level (MCL) - the legal limit designed to protect human health. Maricopa County has 116 such violations. Not all violations cause illness, but repeated exceedances increase risk, especially for children and immunocompromised individuals.
Water facts and the Home Safety Score
The score shown here is the broader Home Safety Score, not a water-quality grade. Model 4.0.0 combines EPA SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, PFAS screening, radon zones, and annual air-quality evidence. Maricopa County has a score of 66/100 (Grade C) across 127 scored of 199 tracked ZIP records.
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Find the Right Filter →Frequently Asked Questions
Is the tap water safe in Maricopa County, Arizona?
Maricopa County has 63 community water systems with 4,612 recorded EPA violations, including 116 health-based. Water quality varies by ZIP code - check your specific location for detailed results.
How many water violations does Maricopa County have?
Maricopa County has 4,612 total EPA violations across 131 directly mapped ZIP records. 116 are health-based.
Which city in Maricopa County has the most water violations?
Gilbert has the most violations in Maricopa County with 1182 recorded EPA violations across 6 ZIP codes.
What contaminants are found in Maricopa County water?
Maricopa County water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. Check your ZIP code for contaminant-specific data.
How can I test my water in Maricopa County?
Contact your local water utility for free or low-cost testing. You can also use a certified home test kit ($20-$50) or hire a certified lab ($150-$400).