City of Stockton
EPA ID: CA3910012 · 191,302 people served · 25 ZIP codes
Unlike fully compliant utilities, City of Stockton has 11 outstanding EPA violations for approximately 191,302 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Stable · Risk tier: High · 95% chance of violation in next 12 months
Violations went from 2 (2021) to 8 (2025). Violation counts have remained relatively steady.
Service Area Map
Coverage area for City of Stockton Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The City of Stockton serves a community with a median household income of $73,292 and an estimated 520,521 residents across its service area. Approximately 65% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: 55% of the population in this service area is classified as disadvantaged under EPA's EJScreen criteria. Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
City of Stockton's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in San Joaquin County, California rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How City of Stockton compares to EPA limits
What This Means For You
Lead at 3 mg/L (action level) exceeds the EPA maximum of 0.015 mg/L (action level). Brain damage in children, kidney & blood pressure in adults. Consider reverse osmosis filtration.
Haloacetic Acids (HAA5) at 5 mg/L exceeds the EPA maximum of 0.06 mg/L. Cancer risk; reproductive & developmental effects. Consider granular activated carbon (GAC) filtration.
Barium at 8 mg/L exceeds the EPA maximum of 2 mg/L.
Stage 2 DBP Rule at 2 mg/L exceeds the EPA maximum of mg/L.
Stage 1 DBP Rule at 1 mg/L exceeds the EPA maximum of mg/L.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 31 detections recorded. 19 exceed federal EPA limits (4 ppt for PFOA/PFOS). 3 exceed state limits.
Lead was detected in this water system. reverse osmosis filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
Similar-sized systems in California
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
City of Stockton (EPA ID: CA3910012) is a community water system in California that serves approximately 191,302 people from surface water sources.
This system provides water to 25 ZIP codes across 5 communities.
Average Home Safety Score: B (74/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 1, 2025 | Lead | Health-based | Unresolved |
| April 1, 2025 | Lead | Health-based | Unresolved |
| January 1, 2025 | Barium | Health-based | Unresolved |
| October 17, 2024 | Stage 2 DBP Rule | Health-based | Unresolved |
| October 17, 2024 | Stage 2 DBP Rule | Monitoring | Unresolved |
| October 1, 2024 | Barium | Health-based | Unresolved |
| July 1, 2024 | Barium | Health-based | Unresolved |
| April 1, 2024 | Barium | Health-based | Unresolved |
| January 1, 2024 | Lead | Monitoring | Resolved |
| January 1, 2024 | Barium | Health-based | Unresolved |
| October 1, 2023 | Barium | Health-based | Unresolved |
| July 1, 2023 | Barium | Health-based | Unresolved |
| April 1, 2023 | Haloacetic Acids (HAA5) | Health-based | Resolved |
| April 1, 2023 | Barium | Health-based | Unresolved |
| January 1, 2023 | Haloacetic Acids (HAA5) | Health-based | Resolved |
| January 1, 2023 | Lead | Health-based | Unresolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Barium | Inorganic | 8 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 5 | Yes |
| Lead | Inorganic | 3 | Yes |
| Stage 2 DBP Rule | Treatment Failure | 2 | Yes |
| Stage 1 DBP Rule | Treatment Failure | 1 | No |
Health Risk Details
Haloacetic Acids (HAA5) (EPA limit: 0.06 mg/L)
Cancer risk; reproductive & developmental effects At-risk groups: pregnant women, infants, long-term consumers of chlorinated municipal water.
Removal methods: granular activated carbon (GAC), carbon block filter, reverse osmosis. Find the right filter →
Lead (EPA limit: 0.015 mg/L (action level))
Brain damage in children, kidney & blood pressure in adults At-risk groups: infants, children under 6, pregnant women.
Removal methods: reverse osmosis, distillation, certified carbon block filter (NSF/ANSI 53). Find the right filter →
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 95201 | 0.0028 mg/L | No | N/A |
| 95205 | 0.0028 mg/L | No | N/A |
| 95206 | 0.0028 mg/L | No | N/A |
| 95207 | 0.0028 mg/L | No | N/A |
| 95208 | 0.0028 mg/L | No | N/A |
| 95209 | 0.0028 mg/L | No | N/A |
| 95210 | 0.0028 mg/L | No | N/A |
| 95212 | 0.0028 mg/L | No | N/A |
| 95213 | 0.0028 mg/L | No | N/A |
| 95214 | 0.0028 mg/L | No | N/A |
| 95219 | 0.0028 mg/L | No | N/A |
| 95267 | 0.0028 mg/L | No | N/A |
| 95269 | 0.0028 mg/L | No | N/A |
| 95296 | 0.0028 mg/L | No | N/A |
| 95297 | 0.0028 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 11 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 14 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 95201 — Stockton
- 95202 — Stockton
- 95203 — Stockton
- 95204 — Stockton
- 95205 — Stockton
- 95206 — Stockton
- 95207 — Stockton
- 95208 — Stockton
- 95209 — Stockton
- 95210 — Stockton
- 95211 — Stockton
- 95212 — Stockton
- 95213 — Stockton
- 95214 — Stockton
- 95215 — Stockton
- 95219 — Stockton
- 95231 — French Camp
- 95234 — Holt
- 95240 — Lodi
- 95242 — Lodi
- 95267 — Stockton
- 95269 — Stockton
- 95296 — Stockton
- 95297 — Stockton
- 95336 — Manteca
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of Stockton (CA3910012) on EPA.gov.
Frequently Asked Questions
Is City of Stockton water safe to drink?
City of Stockton has recorded 11 health-based violations in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does City of Stockton serve?
City of Stockton serves approximately 191,302 people across 25 ZIP codes in California.
Where does City of Stockton get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
- #26 / 100 Highest Exposure Burden (U.S.)
- #10 / 48 Most Unresolved Health Violations (California)
- #3 / 50 Highest Exposure Burden (California)
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of Stockton (EPA ID: CA3910012) — request the latest Consumer Confidence Report or ask about specific contaminants.