California Water Quality Report: 7,292 Violations Across 2,630 ZIPs
2,286 water systems · 2,630 ZIP codes · 7,292 violations · Updated 2026-05-31
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified: 2026-05-31
City Water Quality Map: California
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Violation Trend
EPA violations across all water systems in California.
Cities with Most Violations in California
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | San Diego | C | 1,053 | 5 | 1,422,927 | Details → |
| 2 | Long Beach | A | 513 | 2 | 466,792 | Details → |
| 3 | San Francisco | C | 420 | 4 | 3,643 | Details → |
| 4 | Fresno | B | 290 | 5 | 615,595 | Details → |
| 5 | Sacramento | C | 204 | 5 | 1,005,113 | Details → |
| 6 | Los Angeles | B | 190 | 5 | 4,028,484 | Details → |
| 7 | Stockton | C | 180 | 5 | 208,486 | Details → |
| 8 | Lancaster | D | 144 | 5 | 6,172 | Details → |
| 9 | Pasadena | B | 130 | 4 | 191,916 | Details → |
| 10 | Bakersfield | B | 120 | 5 | 286,339 | Details → |
Cities with Best Water Quality in California
| # | City | Grade | Score | Systems | Population |
|---|---|---|---|---|---|
| 1 | Cutten | A | 99/100 | 1 | 19,807 |
| 2 | Herlong | A | 99/100 | 1 | 2,114 |
| 3 | Camp Meeker | A | 98/100 | 1 | 1,171 |
| 4 | Chula Vista | A | 97/100 | 1 | 191,282 |
| 5 | Orange | A | 97/100 | 3 | 124,234 |
| 6 | El Verano | A | 97/100 | 2 | 23,187 |
| 7 | Crescent City | A | 97/100 | 5 | 20,917 |
| 8 | Shasta Lake | A | 96/100 | 1 | 10,657 |
| 9 | La Mesa | A | 95/100 | 1 | 277,668 |
| 10 | Laguna Hills | A | 95/100 | 4 | 170,959 |
Most Common Contaminants in California
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | 1,748 | 763 | Yes |
| Barium | Inorganic | 582 | 77 | Yes |
| Lead | Inorganic | 562 | 279 | Yes |
| Stage 1 DBP Rule | Treatment Technique | 456 | 395 | No |
| Contaminant 0700 | Other | 368 | 68 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 317 | 118 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 300 | 159 | Yes |
| Combined Radium | Radionuclides | 240 | 28 | Yes |
| Total Coliform | Microbiological | 220 | 138 | No |
| Surface Water Treatment Rule | Treatment Technique | 150 | 120 | No |
Water Quality Overview
California has 2,286 community water systems serving approximately 131,869,617 people across 2,630 ZIP codes. These systems have accumulated 7,292 EPA violations, including 3,328 health-based violations.
Health-based violations account for 46% of all violations in California. These violations indicate contaminant levels that may pose direct risks to human health, as opposed to monitoring or reporting failures.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 3,328 | 45.6% |
| Monitoring/Reporting | 3,964 | 54.4% |
| Total | 7,292 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report — these do not necessarily mean unsafe water, but they mean the water was not properly verified.
Cities with Most Violations
The following cities in California have the highest number of EPA violations:
| Rank | City | Grade | Violations | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | San Diego | C | 1,053 | 5 | 1,422,927 |
| 2 | Long Beach | A | 513 | 2 | 466,792 |
| 3 | San Francisco | C | 420 | 4 | 3,643 |
| 4 | Fresno | B | 290 | 5 | 615,595 |
| 5 | Sacramento | C | 204 | 5 | 1,005,113 |
| 6 | Los Angeles | B | 190 | 5 | 4,028,484 |
| 7 | Stockton | C | 180 | 5 | 208,486 |
| 8 | Lancaster | D | 144 | 5 | 6,172 |
| 9 | Pasadena | B | 130 | 4 | 191,916 |
| 10 | Bakersfield | B | 120 | 5 | 286,339 |
Violation counts are cumulative across all water systems serving each city. Higher counts may reflect larger systems with more monitoring requirements, not necessarily worse water quality.
Cities with Best Water Quality
These California cities maintain Grade A water with zero violations:
| Rank | City | Grade | Score | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Cutten | A | 99/100 | 1 | 19,807 |
| 2 | Herlong | A | 99/100 | 1 | 2,114 |
| 3 | Camp Meeker | A | 98/100 | 1 | 1,171 |
| 4 | Chula Vista | A | 97/100 | 1 | 191,282 |
| 5 | Orange | A | 97/100 | 3 | 124,234 |
| 6 | El Verano | A | 97/100 | 2 | 23,187 |
| 7 | Crescent City | A | 97/100 | 5 | 20,917 |
| 8 | Shasta Lake | A | 96/100 | 1 | 10,657 |
| 9 | La Mesa | A | 95/100 | 1 | 277,668 |
| 10 | Laguna Hills | A | 95/100 | 4 | 170,959 |
Violation Trend Over Time
Year-by-year EPA violations recorded across all water systems in California:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 356 | 356 |
| 2022 | 1,106 | 1,100 |
| 2023 | 1,106 | 1,106 |
| 2024 | 2,125 | 2,125 |
| 2025 | 606 | 606 |
Violations have increased from 356 in 2021 to 606 in 2025. This trend warrants monitoring and may reflect expanded testing requirements rather than worsening quality.
Most Common Contaminants
The following contaminants have caused the most violations across California water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | 1,748 | 763 | Yes |
| Barium | Inorganic | 582 | 77 | Yes |
| Lead | Inorganic | 562 | 279 | Yes |
| Stage 1 DBP Rule | Treatment Technique | 456 | 395 | No |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 317 | 118 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 300 | 159 | Yes |
| Combined Radium | Radionuclides | 240 | 28 | Yes |
| Total Coliform | Microbiological | 220 | 138 | No |
| Surface Water Treatment Rule | Treatment Technique | 150 | 120 | No |
| E. coli | Microbiological | 146 | 130 | Yes |
How to Check Your Water in California
Enter your ZIP code on ZipCheckup for detailed water system data including contaminant levels, violation history, and safety scores
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)
Consider filtration — NSF-certified filters can address specific contaminants found in your area
EPA Enforcement
The EPA and state regulators have taken 7,384 enforcement actions against water systems in California. Enforcement actions range from compliance assistance to formal orders and penalties.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Updated daily.
What are EPA 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. California has 3,328 such violations across its water systems. Not all violations cause illness, but repeated exceedances increase risk, especially for children and immunocompromised individuals.
Understanding water quality grades
ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grade A means few or no violations; Grade F indicates persistent or serious issues. Grades are calculated per ZIP code and aggregated at the city, county, and state level.
Wondering about your tap water?
Water quality varies by ZIP code. Enter yours to see contaminant data, violations, and filtration recommendations specific to your area.
Check Your ZIP Code Water Quality →Frequently Asked Questions
Is the tap water safe to drink in California?
California has 2,286 community water systems with 7,292 recorded EPA violations, including 3,328 health-based. Water quality varies by city and ZIP code — check your specific location for detailed results.
How many water violations does California have?
California has 7,292 total EPA violations across 2,630 ZIP codes. 3,328 are health-based violations that indicate contaminant levels potentially harmful to human health. The remainder are monitoring or reporting violations.
Which city in California has the worst water quality?
San Diego, CA has the most EPA violations among major cities in California with 1053 recorded violations. Check individual ZIP codes for the most accurate picture of your local water quality.
Which city in California has the best water quality?
Cutten, CA ranks among the best for water quality in California with a grade of A. Multiple cities in California maintain strong EPA compliance records.
What contaminants are found in California drinking water?
California water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. The most common violations vary by region — check your ZIP code for contaminant-specific data.