2026 Rankings

Worst ZIP Codes for Lead in Water in California — 2026

Last updated: June 4, 2026

1,899 ZIP codes ranked by Lead (mg/L) #1: ZIP 95363 (Patterson, CA) — 600.0 ppb
Lead Violations Lowest Score Safest Flood Risk Energy Cost Radon PFAS Reliability EJ Index Homebuyer Risk CO & Gas Safest Gas Remediation Burden Unresolved Violations (by Utility) Water Equity (by Utility)

Out of 1,899 ZIP codes with data in California, these are the highest-ranked areas for lead (mg/l). See also: National Worst ZIP Codes for Lead in Water | All California Rankings

Statistic Value
ZIP codes ranked 1,899
Highest value 600.0 ppb
Median value 2.7 ppb
State California

Top 100 Worst ZIP Codes

Rank ZIP Code City State Lead (mg/L) Safety Score
1 95363 Patterson CA 600.0 ppb 90/100
2 95914 Bangor CA 490.0 ppb 66/100
3 95923 Canyon Dam CA 490.0 ppb 66/100
4 95965 Oroville CA 490.0 ppb 86/100
5 95966 Oroville CA 490.0 ppb 86/100
6 95968 Palermo CA 490.0 ppb 65/100
7 93263 Shafter CA 360.0 ppb 79/100
8 91754 Monterey Park CA 250.0 ppb 74/100
9 91755 Monterey Park CA 250.0 ppb 79/100
10 91756 Monterey Park CA 250.0 ppb 79/100
11 93402 Los Osos CA 250.0 ppb 78/100
12 93412 Los Osos CA 250.0 ppb 83/100
13 95970 Princeton CA 250.0 ppb 95/100
14 91701 Rancho Cucamonga CA 200.0 ppb 77/100
15 91729 Rancho Cucamonga CA 200.0 ppb 82/100
16 91730 Rancho Cucamonga CA 200.0 ppb 77/100
17 91737 Rancho Cucamonga CA 200.0 ppb 82/100
18 91739 Rancho Cucamonga CA 200.0 ppb 82/100
19 95676 Robbins CA 200.0 ppb 73/100
20 95991 Yuba City CA 200.0 ppb 83/100
21 95992 Yuba City CA 200.0 ppb 93/100
22 95993 Yuba City CA 200.0 ppb 88/100
23 95632 Galt CA 170.0 ppb 78/100
24 94577 San Leandro CA 160.0 ppb 58/100
25 94578 San Leandro CA 160.0 ppb 58/100
26 94579 San Leandro CA 160.0 ppb 53/100
27 94548 Knightsen CA 153.0 ppb 63/100
28 94561 Oakley CA 153.0 ppb 53/100
29 94558 Napa CA 102.5 ppb 53/100
30 94559 Napa CA 102.5 ppb 53/100
31 94581 Napa CA 102.5 ppb 64/100
32 91962 Pine Valley CA 99.4 ppb 45/100
33 95665 Pine Grove CA 87.9 ppb 45/100
34 95720 Kyburz CA 79.9 ppb 50/100
35 93504 California City CA 74.0 ppb 79/100
36 93505 California City CA 74.0 ppb 79/100
37 93523 Edwards CA 74.0 ppb 63/100
38 93524 Edwards CA 74.0 ppb 53/100
39 93558 Red Mountain CA 74.0 ppb 53/100
40 93560 Rosamond CA 66.0 ppb 28/100
41 95046 San Martin CA 60.0 ppb 46/100
42 95913 Artois CA 60.0 ppb 95/100
43 95943 Glenn CA 60.0 ppb 73/100
44 95988 Willows CA 60.0 ppb 60/100
45 95436 Forestville CA 50.0 ppb 64/100
46 93452 San Simeon CA 45.0 ppb 48/100
47 96041 Hayfork CA 44.1 ppb 66/100
48 96025 Dunsmuir CA 42.2 ppb 57/100
49 95986 Washington CA 41.4 ppb 54/100
50 95757 Elk Grove CA 38.5 ppb 60/100
51 95758 Elk Grove CA 38.5 ppb 70/100
52 91931 Guatay CA 35.0 ppb 33/100
53 95380 Turlock CA 32.0 ppb 65/100
54 95381 Turlock CA 32.0 ppb 66/100
55 95382 Turlock CA 32.0 ppb 70/100
56 91750 La Verne CA 28.0 ppb 69/100
57 92341 Green Valley Lake CA 24.9 ppb 54/100
58 95454 Laytonville CA 23.0 ppb 66/100
59 92564 Murrieta CA 22.0 ppb 42/100
60 95415 Boonville CA 22.0 ppb 70/100
61 93243 Lebec CA 21.0 ppb 58/100
62 95490 Willits CA 20.0 ppb 59/100
63 91906 Campo CA 19.0 ppb 82/100
64 93237 Kaweah CA 19.0 ppb 53/100
65 93262 Sequoia National Park CA 19.0 ppb 53/100
66 93271 Three Rivers CA 19.0 ppb 70/100
67 94951 Penngrove CA 18.5 ppb 68/100
68 92327 Daggett CA 17.0 ppb 17/100
69 92339 Forest Falls CA 16.0 ppb 45/100
70 93247 Lindsay CA 16.0 ppb 28/100
71 95677 Rocklin CA 16.0 ppb 49/100
72 95765 Rocklin CA 16.0 ppb 45/100
73 91316 Encino CA 15.0 ppb 23/100
74 91416 Encino CA 15.0 ppb 17/100
75 91426 Encino CA 15.0 ppb 17/100
76 91436 Encino CA 15.0 ppb 18/100
77 92328 Death Valley CA 15.0 ppb 82/100
78 93208 Camp Nelson CA 15.0 ppb 53/100
79 93265 Springville CA 15.0 ppb 65/100
80 93637 Madera CA 15.0 ppb 74/100
81 93638 Madera CA 15.0 ppb 79/100
82 93639 Madera CA 15.0 ppb 78/100
83 94130 San Francisco CA 15.0 ppb 53/100
84 96019 Shasta Lake CA 15.0 ppb 90/100
85 96079 Shasta Lake CA 15.0 ppb 99/100
86 96089 Shasta Lake CA 15.0 ppb 99/100
87 93627 Helm CA 14.0 ppb 48/100
88 92322 Cedarpines Park CA 13.0 ppb 82/100
89 93267 Strathmore CA 13.0 ppb 39/100
90 93287 Woody CA 13.0 ppb 32/100
91 94945 Novato CA 13.0 ppb 61/100
92 94947 Novato CA 13.0 ppb 56/100
93 94948 Novato CA 13.0 ppb 68/100
94 94949 Novato CA 13.0 ppb 66/100
95 94998 Novato CA 13.0 ppb 68/100
96 95383 Twain Harte CA 12.6 ppb 60/100
97 91903 Alpine CA 12.4 ppb 69/100
98 95724 Norden CA 12.2 ppb 59/100
99 95364 Pinecrest CA 12.1 ppb 55/100
100 92333 Fawnskin CA 12.0 ppb 65/100

Methodology

Lead rankings are based on the 90th percentile lead testing value (PB90) reported by water systems under the Lead and Copper Rule. When CCR data is unavailable, EPA SDWIS lead sampling data is used. The EPA action level for lead is 15 ppb (0.015 mg/L). There is no safe level of lead exposure.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-06-04.

Frequently Asked Questions

What is a dangerous lead level in water?

The EPA action level is 15 parts per billion (ppb). The American Academy of Pediatrics recommends no more than 1 ppb for school drinking water. There is no safe level of lead exposure for children.

How is lead measured in water?

Water systems collect samples from homes with known lead service lines or lead solder. The 90th percentile value (PB90) means 90% of samples tested below that level. If PB90 exceeds 15 ppb, the system must take corrective action.

Explore More Rankings

How this ranking is calculated, data sources, and limitations: Rankings Methodology →

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Disclaimer: Rankings are based on EPA, FEMA, and federal agency data. They reflect historical patterns and risk indicators, not necessarily current conditions. For the most current information, contact your local water utility or request a Consumer Confidence Report.

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