Worst Infrastructure: California

Out of 2,335 ZIP codes with infrastructure data in California, these areas face the highest estimated risk of water pipe failure based on infrastructure age, funding gaps, and violation history.

Statistic	Value
ZIP codes ranked	2,335
Highest risk	63%
Median risk	34%
Average risk	34%
State	California

Top 100 Highest Risk ZIP Codes

Rank	ZIP Code	City	State	Pipe Failure Risk	Risk Level	Safety Score
1	93943	Monterey	CA	63%	Very High	73/100
2	95720	Kyburz	CA	63%	Very High	50/100
3	95950	Grimes	CA	62%	Very High	58/100
4	91125	Pasadena	CA	61%	Very High	81/100
5	93741	Fresno	CA	60%	High	73/100
6	91104	Pasadena	CA	59%	High	81/100
7	93106	Santa Barbara	CA	58%	High	64/100
8	93563	Valyermo	CA	58%	High	78/100
9	91316	Encino	CA	57%	High	23/100
10	94116	San Francisco	CA	57%	High	54/100
11	90073	Los Angeles	CA	56%	High	78/100
12	91436	Encino	CA	56%	High	18/100
13	94108	San Francisco	CA	56%	High	59/100
14	94117	San Francisco	CA	56%	High	53/100
15	94122	San Francisco	CA	56%	High	59/100
16	94127	San Francisco	CA	56%	High	59/100
17	95018	Felton	CA	56%	High	55/100
18	92102	San Diego	CA	55%	High	60/100
19	94021	Loma Mar	CA	55%	High	83/100
20	94112	San Francisco	CA	55%	High	54/100
21	94114	San Francisco	CA	55%	High	59/100
22	94118	San Francisco	CA	55%	High	59/100
23	94123	San Francisco	CA	55%	High	59/100
24	95202	Stockton	CA	55%	High	77/100
25	95690	Walnut Grove	CA	55%	High	75/100
26	91103	Pasadena	CA	54%	High	76/100
27	91107	Pasadena	CA	54%	High	76/100
28	92106	San Diego	CA	54%	High	60/100
29	92107	San Diego	CA	54%	High	60/100
30	92116	San Diego	CA	54%	High	60/100
31	93247	Lindsay	CA	54%	High	28/100
32	93923	Carmel	CA	54%	High	68/100
33	94104	San Francisco	CA	54%	High	59/100
34	94110	San Francisco	CA	54%	High	59/100
35	94121	San Francisco	CA	54%	High	59/100
36	94129	San Francisco	CA	54%	High	53/100
37	94512	Birds Landing	CA	54%	High	73/100
38	95204	Stockton	CA	54%	High	72/100
39	95325	Hornitos	CA	54%	High	53/100
40	95486	Villa Grande	CA	54%	High	65/100
41	95613	Coloma	CA	54%	High	55/100
42	90806	Long Beach	CA	53%	High	70/100
43	90807	Long Beach	CA	53%	High	70/100
44	90810	Long Beach	CA	53%	High	70/100
45	90814	Long Beach	CA	53%	High	70/100
46	91962	Pine Valley	CA	53%	High	45/100
47	92104	San Diego	CA	53%	High	65/100
48	92311	Barstow	CA	53%	High	45/100
49	93240	Lake Isabella	CA	53%	High	59/100
50	94109	San Francisco	CA	53%	High	59/100
51	94133	San Francisco	CA	53%	High	59/100
52	95203	Stockton	CA	53%	High	72/100
53	95231	French Camp	CA	53%	High	62/100
54	95930	Clipper Mills	CA	53%	High	98/100
55	90803	Long Beach	CA	52%	High	65/100
56	90808	Long Beach	CA	52%	High	70/100
57	91105	Pasadena	CA	52%	High	76/100
58	92103	San Diego	CA	52%	High	60/100
59	92105	San Diego	CA	52%	High	60/100
60	92115	San Diego	CA	52%	High	60/100
61	92117	San Diego	CA	52%	High	60/100
62	92119	San Diego	CA	52%	High	65/100
63	92339	Forest Falls	CA	52%	High	45/100
64	92356	Lucerne Valley	CA	52%	High	69/100
65	93244	Lemon Cove	CA	52%	High	41/100
66	93534	Lancaster	CA	52%	High	48/100
67	93728	Fresno	CA	52%	High	70/100
68	94020	La Honda	CA	52%	High	74/100
69	94115	San Francisco	CA	52%	High	59/100
70	94130	San Francisco	CA	52%	High	53/100
71	94132	San Francisco	CA	52%	High	59/100
72	94559	Napa	CA	52%	High	53/100
73	95419	Camp Meeker	CA	52%	High	98/100
74	96155	South Lake Tahoe	CA	52%	High	80/100
75	90805	Long Beach	CA	51%	High	65/100
76	91106	Pasadena	CA	51%	High	81/100
77	92061	Pauma Valley	CA	51%	High	91/100
78	92109	San Diego	CA	51%	High	55/100
79	92111	San Diego	CA	51%	High	65/100
80	92113	San Diego	CA	51%	High	55/100
81	92114	San Diego	CA	51%	High	60/100
82	93283	Weldon	CA	51%	High	55/100
83	93666	Sultana	CA	51%	High	64/100
84	94508	Angwin	CA	51%	High	86/100
85	94556	Moraga	CA	51%	High	66/100
86	94569	Port Costa	CA	51%	High	73/100
87	95006	Boulder Creek	CA	51%	High	65/100
88	96111	Floriston	CA	51%	High	83/100
89	90062	Los Angeles	CA	50%	High	79/100
90	91108	San Marino	CA	50%	High	76/100
91	92333	Fawnskin	CA	50%	High	65/100
92	93001	Ventura	CA	50%	High	48/100
93	93433	Grover Beach	CA	50%	High	58/100
94	93535	Lancaster	CA	50%	High	43/100
95	94060	Pescadero	CA	50%	High	63/100
96	94131	San Francisco	CA	50%	High	59/100
97	94134	San Francisco	CA	50%	High	53/100
98	94602	Oakland	CA	50%	High	74/100
99	94707	Berkeley	CA	50%	High	63/100
100	95565	Scotia	CA	50%	High	86/100

Methodology

Infrastructure risk rankings combine four data sources, each weighted equally (25%): (1) EPA Drinking Water Infrastructure Needs Survey (DWINS 2023) — state-level 20-year funding gap per capita for pipe replacement, treatment, and storage; (2) Census ACS housing vintage — percentage of homes built before 1980, when lead solder and galvanized pipes were common; (3) EPA SDWIS violation and enforcement data — system-level compliance history; (4) Lead and Copper Rule indicators — service line material inventories and 90th percentile lead testing results. The combined score is normalized to a 0-100% probability scale.

Data sources: EPA DWINS 2023, Census ACS, EPA SDWIS, Lead and Copper Rule data. Last updated: 2026-06-04.

Frequently Asked Questions

What does pipe failure probability mean?

Pipe failure probability estimates the likelihood of water main breaks, lead contamination from corroded pipes, or service disruptions based on infrastructure age, state funding gaps, violation history, and lead indicators. It is not a prediction of imminent failure, but a risk assessment based on known factors.

How is infrastructure risk calculated?

The risk score combines four equally weighted factors: state-level infrastructure funding gap per capita (from EPA DWINS 2023), housing vintage (Census ACS pre-1980 housing percentage), water system violation and enforcement history (EPA SDWIS), and lead exposure indicators (service line probability and testing results).

What can homeowners do about aging infrastructure?

Test your tap water annually, especially for lead. Check if your home has a lead service line through your water utility. Consider a whole-house water filter (NSF/ANSI 53 certified). Review your water system Consumer Confidence Report for violation history.

Does high risk mean my water is unsafe right now?

Not necessarily. Infrastructure risk indicates long-term vulnerability, not current contamination. However, areas with aging pipes and high violation counts have a statistically higher chance of water quality issues. Regular testing is the best way to verify your water safety.

Worst Infrastructure: California — 2026 Rankings