STATE REPORT CA 2 ALERTS 3328 HEALTH VIOLATIONS

California Water: 7.3K Violations — 2630 ZIPs

2630 ZIP codes · 1809 water systems · UPC plumbing code · Updated 2026-06-03

Data: EPA SDWIS, NWS, State plumbing boards, Rewiring America Last verified: 2026-06-03

2630
ZIP Codes
1809
Water Systems
1452
ZIPs with Violations
2
Active Alerts
UPC
Plumbing Code
B · 73
Avg Safety Score
40
ZIPs Exceeding Lead Limit
3%
High Radon Risk (Zone 1)
#15
of 51 States
63%
ZIPs Rated A or B
55%
ZIPs with Violations
B
California average: 73/100 — ranked #15 of 51 states. 6 points above the national average (67). 63% of ZIP codes scored A or B.

Statewide monitoring data places California in the above-average tier for public drinking water safety.

Score Distribution

How California's 2630 ZIP codes are distributed across safety grades.

386
A
1274
B
649
C
300
D
21
F
85-10070-8455-6940-540-39

Home Safety Scores by State

Loading map…
F (0-49) D (50-64) C (65-74) B (75-84) A (85+)

Data: EPA SDWIS, FEMA NFIP, EPA Radon, USGS Earthquake Hazards, NIFC Wildfire • 2026-06-03

Top 10 Safest ZIP Codes in California

Highest Home Safety Scores in the state.

#ZIP CodeCityCountyScoreGrade
1 91909 Chula VistaSan Diego 99 A
2 91912 Chula VistaSan Diego 99 A
3 91913 Chula VistaSan Diego 99 A
4 91914 Chula VistaSan Diego 99 A
5 91921 Chula VistaSan Diego 99 A
6 91934 JacumbaSan Diego 99 A
7 91943 La MesaSan Diego 99 A
8 91944 La MesaSan Diego 99 A
9 92013 CarlsbadSan Diego 99 A
10 92018 CarlsbadSan Diego 99 A

10 Lowest-Scoring ZIP Codes in California

#ZIP CodeCityCountyScoreGradeViolations
1 92327 DaggettSan Bernardino 17 F 21
2 91426 EncinoLos Angeles 17 F 18
3 91416 EncinoLos Angeles 17 F 18
4 91436 EncinoLos Angeles 18 F 18
5 91316 EncinoLos Angeles 23 F 18
6 93560 RosamondKern 28 F 30
7 93247 LindsayTulare 28 F 22
8 93287 WoodyKern 32 F 7
9 91931 GuataySan Diego 33 F 14
10 93669 WishonMadera 35 F 6

County Rankings

Water quality breakdown by county. 58 counties with data in California.

Loading county map…
F (0-49) D (50-64) C (65-74) B (75-84) A (85+)

County-level aggregation of ZIP code safety scores • EPA SDWIS, FEMA NFIP, EPA Radon, USGS, NIFC

CountyAvg ScoreGradeZIPsBest ZIPWorst ZIP
Los Angeles 72 B 459 90220 (83) 91426 (17)
Inyo 59 C 42 93546 (83) 91604 (50)
Kern 65 C 102 93206 (83) 93560 (28)
Orange 87 A 143 92654 (99) 92626 (52)
Butte 78 B 29 95930 (98) 95968 (65)
Ventura 58 C 45 93021 (70) 92101 (35)
San Bernardino 70 B 114 91709 (83) 92327 (17)
Riverside 73 B 101 92230 (83) 92562 (37)
San Joaquin 78 B 55 95230 (99) 94960 (55)
San Diego 72 B 187 91909 (99) 91931 (33)
Imperial 80 B 22 92283 (93) 92257 (65)
Madera 60 C 16 93636 (79) 93669 (35)
Lassen 75 B 18 96113 (99) 92624 (60)
Lake 75 B 21 95443 (93) 95458 (60)
Santa Barbara 63 C 41 93014 (70) 93429 (53)
Tulare 63 C 36 93603 (82) 93247 (28)
Kings 75 B 9 93232 (97) 93239 (51)
Fresno 70 B 102 93625 (83) 93627 (48)
San Luis Obispo 71 B 34 93412 (83) 93452 (48)
Monterey 71 B 36 93922 (83) 95012 (53)
Mono 68 C 6 93517 (79) 96133 (53)
Del Norte 84 B 9 95532 (99) 95564 (66)
Merced 77 B 22 95324 (95) 93620 (55)
San Mateo 72 B 35 94005 (83) 94070 (50)
Santa Clara 78 B 104 94023 (83) 95046 (46)
Sacramento 80 B 133 95611 (99) 95757 (60)
San Francisco 55 C 59 94102 (59) 94188 (53)
Alameda 69 C 75 94540 (83) 95042 (53)
Napa 71 B 13 94550 (95) 94559 (53)
Contra Costa 68 C 35 94516 (81) 94575 (45)
Solano 79 B 18 94592 (99) 94533 (65)
Sonoma 80 B 63 95406 (99) 95462 (50)
Marin 74 B 33 94966 (95) 94941 (55)
Santa Cruz 64 C 22 95077 (83) 95060 (48)
Mendocino 74 B 29 95445 (95) 95490 (59)
San Benito 67 C 5 95075 (75) 95023 (60)
Calaveras 63 C 16 95247 (77) 95257 (53)
Amador 62 C 18 95640 (81) 95665 (45)
Tuolumne 64 C 16 95310 (83) 95375 (53)
Mariposa 58 C 6 95338 (81) 95389 (53)
Stanislaus 84 B 26 95352 (99) 95367 (62)
Humboldt 82 B 41 95511 (99) 95556 (50)
Trinity 81 B 10 95527 (94) 96041 (66)
Placer 69 C 31 95604 (83) 95765 (45)
Yolo 84 B 19 95937 (95) 95607 (66)
El Dorado 70 B 24 95636 (82) 95720 (50)
Alpine 62 C 5 95646 (83) 95735 (53)
Sutter 85 A 7 95982 (95) 95676 (73)
Glenn 81 B 12 95939 (99) 95988 (60)
Yuba 67 C 13 95692 (83) 95972 (53)
Nevada 68 C 14 95949 (83) 95960 (52)
Sierra 75 B 7 95910 (83) 95944 (53)
Colusa 80 B 5 95912 (90) 95957 (65)
Plumas 66 C 14 96137 (83) 96129 (53)
Shasta 82 B 31 96016 (99) 96096 (66)
Siskiyou 83 B 19 96014 (99) 96025 (57)
Modoc 78 B 9 96015 (99) 96116 (66)
Tehama 81 B 14 96092 (95) 96078 (66)

Most Common Contaminants in California

Contaminant / RuleCategoryZIPs AffectedViolationsHealth Risk
Stage 2 DBP Rule Treatment Technique 763 1748 Yes
Consumer Confidence Report Rule Reporting 459 1641 Yes
Stage 1 DBP Rule Treatment Technique 395 456 No
Lead Inorganic 279 562 Yes
Total Trihalomethanes (TTHM) Disinfection Byproducts 159 300 Yes
Total Coliform Microbiological 138 220 No
E. coli Microbiological 130 146 Yes
Surface Water Treatment Rule Treatment Technique 120 150 No

Overview

We track water quality, weather alerts, plumbing regulations, and energy rebates for 2630 ZIP codes across California, covering 1809 community water systems that serve approximately 34,793,655 people.

1452 of 2630 ZIP codes (55%) have recorded EPA violations. 3328 health-based violations have been documented.

Active Weather Alerts

2 active alerts in California. Severe weather can directly affect tap water quality — flooding, power outages, and infrastructure damage may lead to boil-water advisories.

Alert Severity Areas
Frost Advisory Minor North Central and Southeast Siskiyou County; Northeast Siskiyou and Northwest Modoc Counties; Modoc County; Klamath Basin; Northern and Eastern Klamath County and Western Lake County; Central and Eastern Lake County
Air Quality Alert Unknown Imperial Valley

View all California alerts →

Plumbing Regulations

California follows the California Plumbing Code (based on UPC) (2022 edition).

  • Plumbing code: UPC (2022)
  • Homeowner DIY: Licensed plumber required
  • Water heater permit: Required
  • Annual backflow test: Required
  • Seismic strapping: Required

Full California regulations →

Areas with Most Violations

ZIP Code City Safety Score Violations Health-Based System
93283 Weldon C 48 46 Tradewind Water Assoc.
95326 Hughson B 36 35 City of Hughson,
92311 Barstow D 31 24 Usmc Nebo (barstow)
92312 Barstow F 31 24 Usmc Nebo (barstow)
93560 Rosamond F 30 29 Rosamond Csd
94561 Oakley D 29 29 Diablo Water District
92069 San Marcos C 28 6 Vallecitos Water District
92078 San Marcos B 28 6 Vallecitos Water District
92079 San Marcos C 28 6 Vallecitos Water District
92096 San Marcos C 28 6 Vallecitos Water District

Areas with No Violations

ZIP Code City Safety Score System Population
90069 West Hollywood D LOS ANGELES-CITY, DEPT. OF WATER & POWER 3,875,566
90090 Dodgertown D LOS ANGELES-CITY, DEPT. OF WATER & POWER 3,875,566
90094 Playa Vista D LOS ANGELES-CITY, DEPT. OF WATER & POWER 3,875,566
90201 Bell Gardens B City of Bell Gardens 11,437
90202 Bell D MAYWOOD MUTUAL WATER CO. #2 6,349
90220 Compton B Compton-city, Water Department 74,877
90221 Compton B Compton-city, Water Department 74,877
90222 Compton B Compton-city, Water Department 74,877
90223 Compton B Compton-city, Water Department 74,877
90224 Compton B Compton-city, Water Department 74,877

Home Safety Score

Average Home Safety Score for California: B (73/100)

Lead & Copper

  • Average lead level (90th percentile): 0.0061 mg/L (EPA action level: 0.015 mg/L)
  • 40 ZIP codes exceed the EPA lead action level

Radon Risk

  • High risk (Zone 1): 86 ZIP codes (3%)
  • Moderate risk (Zone 2): 1547 ZIP codes
  • Low risk (Zone 3): 997 ZIP codes

ZIP Code Reports for California

Largest Communities

ZIP Code City Population Safety Grade Violations
90059 Los Angeles 4,474,439 B 2
90045 Los Angeles 4,445,985 B 2
90061 Los Angeles 4,407,472 B 2
90041 Los Angeles 4,381,612 B 2
90248 Gardena 4,360,737 D 0
90047 Los Angeles 4,350,942 C 2
90044 Los Angeles 4,306,224 B 2
90247 Gardena 4,259,489 C 0
90039 Los Angeles 4,217,268 B 2
90040 Los Angeles 4,196,600 B 2
90022 Los Angeles 4,185,163 B 2
90023 Los Angeles 4,185,163 B 2
90032 Los Angeles 4,180,958 B 2
90063 Los Angeles 4,180,958 B 2
91321 Newhall 4,169,656 B 0
90002 Los Angeles 4,158,951 B 2
90001 Los Angeles 4,107,421 B 2
90058 Los Angeles 4,107,421 B 2
91214 La Crescenta 4,100,191 B 0
90003 Los Angeles 4,091,984 B 2

Lowest Safety Scores

ZIP Code City Score Grade Violations
91416 Encino 17 F 18
91426 Encino 17 F 18
92327 Daggett 17 F 21
91436 Encino 18 F 18
91316 Encino 23 F 18

Highest Safety Scores

ZIP Code City Score Grade Violations
91909 Chula Vista 99 A 0
91912 Chula Vista 99 A 0
91913 Chula Vista 99 A 0
91914 Chula Vista 99 A 0
91921 Chula Vista 99 A 0

All 2630 ZIP Codes in California

Data Sources

Updated daily.

Frequently Asked Questions

Is the water safe to drink in California?

California has 1809 community water systems serving 34,793,655 people across 2630 ZIP codes. There are 7,292 recorded violations, including 3328 health-based. 1452 of 2630 ZIP codes have at least one violation.

What plumbing code does California follow?

California follows the UPC plumbing code. A licensed plumber is generally required for plumbing work.

Is lead a concern in California's drinking water?

40 ZIP codes in California have lead levels exceeding the EPA action level of 0.015 mg/L.

What is the radon risk in California?

3% of ZIP codes in California fall in EPA Radon Zone 1 (highest risk).

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