Water Quality in Stockton, CA: 180 Violations — Grade C
Grade C · Score 62/100 · 5 water systems · Updated 2026-05-03
Stockton'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
Water systems in Stockton, CA have accumulated 180 EPA violations across the full compliance record — a dataset that captures reportable health-based exceedances, monitoring lapses, and enforcement actions filed with the federal Safe Drinking Water Information System.
Water Quality Map: Stockton, CA
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Stockton
Water quality varies across Stockton's 20 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 95203 | B | 72 | 9 | 6 | View report → |
| 95204 | B | 72 | 9 | 6 | View report → |
| 95206 | B | 72 | 9 | 6 | View report → |
| 95207 | B | 72 | 9 | 6 | View report → |
| 95212 | B | 72 | 9 | 6 | View report → |
| 95215 | B | 72 | 9 | 6 | View report → |
| 95219 | B | 72 | 9 | 6 | View report → |
| 95201 | B | 77 | 9 | 6 | View report → |
| 95202 | B | 77 | 9 | 6 | View report → |
| 95205 | B | 77 | 9 | 6 | View report → |
| 95208 | B | 77 | 9 | 6 | View report → |
| 95209 | B | 77 | 9 | 6 | View report → |
| 95210 | B | 77 | 9 | 6 | View report → |
| 95211 | B | 77 | 9 | 6 | View report → |
| 95213 | B | 77 | 9 | 6 | View report → |
Violation Trend
EPA violations recorded for water systems serving Stockton.
Water Quality Overview
Stockton, California receives a water quality grade of C with an overall score of 62 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Stockton have accumulated 180 EPA violations, including 120 health-based violations. These violations are tracked across 20 ZIP codes serving approximately 208,486 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Stockton'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 Stockton water systems is 0.0028 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 66% of homes built before 1986, Stockton 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
Stockton is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Stockton
Stockton is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 208,486 people across 20 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 140 enforcement actions against water systems serving Stockton. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Stockton
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 Stockton Water Systems
The following contaminants have been detected or caused violations across Stockton's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 0.06 mg/L | 100 | 20 | Yes |
| Stage 2 DBP Rule | Treatment Technique | N/A | 40 | 20 | Yes |
| Stage 1 DBP Rule | Treatment Technique | N/A | 20 | 20 | No |
| Lead | Inorganic | 0.015 mg/L | 20 | 20 | 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 Stockton:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2022 | 20 | 20 |
| 2023 | 80 | 80 |
| 2024 | 20 | 20 |
Violation counts have remained stable over the observed period.
EPA Enforcement History
The EPA and state regulators have taken 7 enforcement actions against water systems serving Stockton. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-16 | State Order Extension |
| 2025-03-04 | State Filed Suit |
| 2025-01-06 | State Order Extension |
| 2024-06-18 | State Order Extension |
| 2023-10-19 | State Filed Suit |
| 2023-04-27 | State Filed Suit |
| 2023-01-25 | State Filed Suit |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-16.
Stockton vs. Nearby California Cities
How Stockton's water quality compares to similar cities in California:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Stockton | C | 180 | 5 | 208,486 |
| San Gabriel | C | 0 | 2 | 208,233 |
| Rancho Santa Margarita | A | 1 | 3 | 207,973 |
| Oxnard | C | 21 | 5 | 209,147 |
Water Quality by ZIP Code in Stockton
Water quality varies across Stockton's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 95203 | 72 | B | 9 | 6 |
| 95204 | 72 | B | 9 | 6 |
| 95206 | 72 | B | 9 | 6 |
| 95207 | 72 | B | 9 | 6 |
| 95212 | 72 | B | 9 | 6 |
| 95215 | 72 | B | 9 | 6 |
| 95219 | 72 | B | 9 | 6 |
| 95201 | 77 | B | 9 | 6 |
| 95202 | 77 | B | 9 | 6 |
| 95205 | 77 | B | 9 | 6 |
| 95297 | 77 | B | 9 | 6 |
| 95296 | 77 | B | 9 | 6 |
| 95269 | 77 | B | 9 | 6 |
| 95267 | 77 | B | 9 | 6 |
| 95214 | 77 | B | 9 | 6 |
Common Questions About Stockton Water
These are the most common questions residents search for about water quality in Stockton, California:
Is Stockton water hard or soft? Water hardness varies by source. Stockton's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Stockton tap water? Stockton's water receives a grade of C (62/100). There are 120 health-based violations — consider filtration.
What is the best water filter for Stockton? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Stockton vs. California Average
Understanding how Stockton compares to the broader California 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 Stockton.
ZIP Codes in Stockton
Stockton spans 20 ZIP codes. The ZIP with the lowest water quality score is 95201. 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.