Water Quality in Nogales, AZ: 123 Violations — Grade C
Grade C · Score 67/100 · 5 water systems · Updated 2026-05-03
Nogales'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
Local water systems serving Nogales, AZ carry 123 EPA violations on record in the federal compliance database — documented events spanning categories from maximum contaminant level exceedances to monitoring requirements tracked by the national Safe Drinking Water program.
Water Quality by ZIP Code in Nogales
Water quality varies across Nogales's 3 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 85621 | C | 63 | 41 | 4 | View report → |
| 85628 | C | 68 | 41 | 4 | View report → |
| 85662 | B | 71 | 41 | 4 | View report → |
Violation Trend
EPA violations recorded for water systems serving Nogales.
Water Quality Overview
Nogales, Arizona receives a water quality grade of C with an overall score of 67 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Nogales have accumulated 123 EPA violations, including 12 health-based violations. These violations are tracked across 3 ZIP codes serving approximately 25,023 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Nogales'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 Nogales water systems is 0.0010 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 71% of homes built before 1986, Nogales 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
Nogales is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Nogales
Nogales is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 25,023 people across 3 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 30 enforcement actions against water systems serving Nogales. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Nogales
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 Nogales Water Systems
The following contaminants have been detected or caused violations across Nogales's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Revised Total Coliform Rule | Microbiological | N/A | 18 | 3 | No |
| Lead and Copper Rule | Treatment Technique | N/A | 18 | 3 | No |
| Barium | Inorganic | 2 mg/L | 15 | 3 | No |
| Stage 1 DBP Rule | Treatment Technique | N/A | 15 | 3 | No |
| Stage 2 DBP Rule | Treatment Technique | N/A | 12 | 3 | Yes |
| Lead | Inorganic | 0.015 mg/L | 9 | 3 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 9 | 3 | No |
| Surface Water Treatment Rule | Treatment Technique | N/A | 9 | 3 | No |
| Total Organic Carbon | Disinfection Byproducts | N/A | 6 | 3 | No |
| Total Coliform | Microbiological | N/A | 3 | 3 | 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 Nogales:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 3 | 3 |
| 2024 | 12 | 12 |
| 2025 | 3 | 3 |
Violation counts have remained stable over the observed period.
EPA Enforcement History
The EPA and state regulators have taken 9 enforcement actions against water systems serving Nogales. Recent actions:
| Date | Action Type |
|---|---|
| 2025-10-17 | EPA Formal Action |
| 2025-09-10 | State Order Extension |
| 2025-07-31 | State Informal Action |
| 2025-07-31 | State Order Extension |
| 2025-07-15 | State Order Extension |
| 2025-07-10 | State Informal Action |
| 2025-07-07 | State Informal Action |
| 2025-07-07 | State Order Extension |
| 2025-05-27 | State Informal Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-10-17.
Nogales vs. Nearby Arizona Cities
How Nogales's water quality compares to similar cities in Arizona:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Nogales | C | 123 | 5 | 25,023 |
| Catalina | B | 8 | 5 | 24,699 |
| Sun City West | B | 4 | 1 | 25,796 |
| Fort Mcdowell | D | 0 | 1 | 26,026 |
Water Quality by ZIP Code in Nogales
Water quality varies across Nogales's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
Common Questions About Nogales Water
These are the most common questions residents search for about water quality in Nogales, Arizona:
Is Nogales water hard or soft? Water hardness varies by source. Nogales's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Nogales tap water? Nogales's water receives a grade of C (67/100). There are 12 health-based violations — consider filtration.
What is the best water filter for Nogales? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Nogales vs. Arizona Average
Understanding how Nogales 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 Nogales.
ZIP Codes in Nogales
Nogales spans 3 ZIP codes. The ZIP with the lowest water quality score is 85621. 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.