Water Quality in Flagstaff, AZ: 120 Violations — Grade C
Grade C · Score 65/100 · 5 water systems · Updated 2026-05-03
Flagstaff'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
The compliance record maintained by the EPA for Flagstaff, AZ documents 120 water violations — each tied to a specific public water system and assigned a violation category in the federal Safe Drinking Water dataset.
Water Quality Map: Flagstaff, AZ
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Flagstaff
Water quality varies across Flagstaff's 6 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 86004 | C | 59 | 20 | 0 | View report → |
| 86001 | C | 64 | 20 | 0 | View report → |
| 86002 | C | 65 | 20 | 0 | View report → |
| 86003 | C | 65 | 20 | 0 | View report → |
| 86011 | C | 65 | 20 | 0 | View report → |
| 86005 | C | 69 | 20 | 0 | View report → |
Violation Trend
EPA violations recorded for water systems serving Flagstaff.
Water Quality Overview
Flagstaff, Arizona receives a water quality grade of C with an overall score of 65 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Flagstaff have accumulated 120 EPA violations (all monitoring/reporting type). These violations are tracked across 6 ZIP codes serving approximately 92,709 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Flagstaff'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 Flagstaff water systems is 0.0029 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
Radon Risk
Flagstaff is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Flagstaff
Flagstaff is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 92,709 people across 6 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 60 enforcement actions against water systems serving Flagstaff. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Flagstaff
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 Flagstaff Water Systems
The following contaminants have been detected or caused violations across Flagstaff's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Chlorite | Disinfection Byproducts | 1 mg/L | 18 | 6 | No |
| E. coli | Microbiological | N/A | 12 | 6 | No |
| Stage 1 DBP Rule | Treatment Technique | N/A | 12 | 6 | No |
| Radium-228 | Radionuclides | 5 pCi/L | 6 | 6 | No |
| Surface Water Treatment Rule | Treatment Technique | N/A | 6 | 6 | No |
| Fecal Coliform | Microbiological | N/A | 6 | 6 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 6 | 6 | No |
| Total Organic Carbon | Disinfection Byproducts | N/A | 6 | 6 | No |
| Dichloroacetic Acid | Disinfection Byproducts | 0.06 mg/L | 6 | 6 | No |
| Revised Total Coliform Rule | Microbiological | N/A | 6 | 6 | No |
| Total Coliform | Microbiological | N/A | 6 | 6 | 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 Flagstaff:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2023 | 6 | 6 |
| 2024 | 12 | 12 |
Violations have increased from 6 in 2023 to 12 in 2024. This trend warrants monitoring.
EPA Enforcement History
The EPA and state regulators have taken 10 enforcement actions against water systems serving Flagstaff. Recent actions:
| Date | Action Type |
|---|---|
| 2025-08-12 | State Informal Action |
| 2025-08-12 | State Order Extension |
| 2025-07-31 | State Informal Action |
| 2025-07-31 | State Order Extension |
| 2025-07-22 | State Order Extension |
| 2025-04-30 | State Informal Action |
| 2025-04-30 | State Order Extension |
| 2025-01-30 | State Order Extension |
| 2025-01-30 | State Informal Action |
| 2025-01-03 | State Informal Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-08-12.
Flagstaff vs. Nearby Arizona Cities
How Flagstaff's water quality compares to similar cities in Arizona:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Flagstaff | C | 120 | 5 | 92,709 |
| Queen Creek | B | 105 | 3 | 97,812 |
| San Tan Valley | C | 62 | 4 | 98,772 |
| Maricopa | C | 288 | 5 | 101,115 |
Water Quality by ZIP Code in Flagstaff
Water quality varies across Flagstaff's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 86004 | 59 | C | 20 | 0 |
| 86001 | 64 | C | 20 | 0 |
| 86002 | 65 | C | 20 | 0 |
| 86003 | 65 | C | 20 | 0 |
| 86011 | 65 | C | 20 | 0 |
| 86005 | 69 | C | 20 | 0 |
Common Questions About Flagstaff Water
These are the most common questions residents search for about water quality in Flagstaff, Arizona:
Is Flagstaff water hard or soft? Water hardness varies by source. Flagstaff's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Flagstaff tap water? Flagstaff's water receives a grade of C (65/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Flagstaff? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Flagstaff vs. Arizona Average
Understanding how Flagstaff compares to the broader Arizona 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 Flagstaff.
ZIP Codes in Flagstaff
Flagstaff spans 6 ZIP codes. The ZIP with the lowest water quality score is 86001. 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.