Least Reliable Water Systems in Hawaii — 2026

Out of 137 ZIP codes with data in Hawaii, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Hawaii Rankings

Statistic	Value
ZIP codes ranked	137
Lowest value	35/100
Median value	80/100
State	Hawaii

100 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Reliability Score	Safety Score
1	96770	Maunaloa	HI	35/100	80/100
2	96742	Kalaupapa	HI	45/100	86/100
3	96757	Kualapuu	HI	50/100	86/100
4	96763	Lanai City	HI	50/100	85/100
5	96857	Schofield Barracks	HI	50/100	86/100
6	96744	Kaneohe	HI	60/100	82/100
7	96725	Holualoa	HI	62/100	86/100
8	96720	Hilo	HI	70/100	70/100
9	96721	Hilo	HI	70/100	86/100
10	96729	Hoolehua	HI	73/100	88/100
11	96748	Kaunakakai	HI	73/100	90/100
12	96701	Aiea	HI	75/100	82/100
13	96704	Captain Cook	HI	75/100	73/100
14	96706	Ewa Beach	HI	75/100	60/100
15	96707	Kapolei	HI	75/100	73/100
16	96708	Haiku	HI	75/100	70/100
17	96709	Kapolei	HI	75/100	66/100
18	96726	Honaunau	HI	75/100	66/100
19	96739	Keauhou	HI	75/100	66/100
20	96740	Kailua Kona	HI	75/100	72/100
21	96745	Kailua Kona	HI	75/100	82/100
22	96746	Kapaa	HI	75/100	55/100
23	96750	Kealakekua	HI	75/100	73/100
24	96751	Kealia	HI	75/100	88/100
25	96753	Kihei	HI	75/100	72/100
26	96756	Koloa	HI	75/100	72/100
27	96773	Ninole	HI	75/100	88/100
28	96774	Ookala	HI	75/100	88/100
29	96779	Paia	HI	75/100	73/100
30	96782	Pearl City	HI	75/100	82/100
31	96784	Puunene	HI	75/100	88/100
32	96788	Pukalani	HI	75/100	88/100
33	96797	Waipahu	HI	75/100	87/100
34	96853	J B P H H	HI	75/100	66/100
35	96859	Tripler Army Medical Center	HI	75/100	66/100
36	96861	Camp H M Smith	HI	75/100	66/100
37	96703	Anahola	HI	80/100	77/100
38	96705	Eleele	HI	80/100	66/100
39	96710	Hakalau	HI	80/100	66/100
40	96712	Haleiwa	HI	80/100	55/100
41	96713	Hana	HI	80/100	87/100
42	96714	Hanalei	HI	80/100	72/100
43	96716	Hanapepe	HI	80/100	65/100
44	96717	Hauula	HI	80/100	60/100
45	96718	Hawaii National Park	HI	80/100	86/100
46	96719	Hawi	HI	80/100	66/100
47	96722	Princeville	HI	80/100	82/100
48	96727	Honokaa	HI	80/100	73/100
49	96728	Honomu	HI	80/100	88/100
50	96730	Kaaawa	HI	80/100	60/100
51	96731	Kahuku	HI	80/100	87/100
52	96732	Kahului	HI	80/100	65/100
53	96733	Kahului	HI	80/100	70/100
54	96734	Kailua	HI	80/100	55/100
55	96737	Ocean View	HI	80/100	66/100
56	96738	Waikoloa	HI	80/100	87/100
57	96741	Kalaheo	HI	80/100	87/100
58	96743	Kamuela	HI	80/100	71/100
59	96747	Kaumakani	HI	80/100	87/100
60	96749	Keaau	HI	80/100	73/100
61	96752	Kekaha	HI	80/100	77/100
62	96754	Kilauea	HI	80/100	82/100
63	96755	Kapaau	HI	80/100	66/100
64	96759	Kunia	HI	80/100	88/100
65	96760	Kurtistown	HI	80/100	73/100
66	96761	Lahaina	HI	80/100	85/100
67	96762	Laie	HI	80/100	77/100
68	96764	Laupahoehoe	HI	80/100	88/100
69	96765	Lawai	HI	80/100	73/100
70	96767	Lahaina	HI	80/100	95/100
71	96769	Makaweli	HI	80/100	73/100
72	96772	Naalehu	HI	80/100	66/100
73	96776	Paauilo	HI	80/100	88/100
74	96777	Pahala	HI	80/100	87/100
75	96778	Pahoa	HI	80/100	82/100
76	96780	Papaaloa	HI	80/100	73/100
77	96781	Papaikou	HI	80/100	88/100
78	96783	Pepeekeo	HI	80/100	88/100
79	96786	Wahiawa	HI	80/100	87/100
80	96789	Mililani	HI	80/100	73/100
81	96790	Kula	HI	80/100	95/100
82	96791	Waialua	HI	80/100	60/100
83	96792	Waianae	HI	80/100	55/100
84	96796	Waimea	HI	80/100	65/100
85	96801	Honolulu	HI	80/100	87/100
86	96802	Honolulu	HI	80/100	88/100
87	96803	Honolulu	HI	80/100	87/100
88	96804	Honolulu	HI	80/100	87/100
89	96805	Honolulu	HI	80/100	88/100
90	96806	Honolulu	HI	80/100	88/100
91	96807	Honolulu	HI	80/100	88/100
92	96808	Honolulu	HI	80/100	88/100
93	96809	Honolulu	HI	80/100	88/100
94	96810	Honolulu	HI	80/100	87/100
95	96811	Honolulu	HI	80/100	87/100
96	96812	Honolulu	HI	80/100	88/100
97	96813	Honolulu	HI	80/100	82/100
98	96814	Honolulu	HI	80/100	87/100
99	96815	Honolulu	HI	80/100	77/100
100	96816	Honolulu	HI	80/100	77/100

Methodology

Water system reliability scores (0-100) combine violation frequency, violation recency, resolution rate, and system size. Systems with repeated health-based violations and unresolved issues score lowest. The reliability score focuses specifically on the water utility performance, distinct from the broader Home Safety Score.

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: 2026-04-13.

Frequently Asked Questions

What does a low water reliability score mean?

A low reliability score (below 50) indicates a water system with frequent violations, poor resolution rates, or recurring compliance issues. These systems may have aging infrastructure, inadequate treatment, or management challenges.

How is reliability different from safety score?

The reliability score focuses specifically on the water utility performance (violations, resolution, compliance). The Home Safety Score is broader, also including lead risk, radon, and flood data. A ZIP code can have a reliable water system but still have high radon or flood risk.