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	96757	Kualapuu	HI	50/100	86/100
3	96763	Lanai City	HI	50/100	85/100
4	96857	Schofield Barracks	HI	50/100	86/100
5	96744	Kaneohe	HI	60/100	82/100
6	96725	Holualoa	HI	62/100	86/100
7	96720	Hilo	HI	70/100	70/100
8	96729	Hoolehua	HI	73/100	88/100
9	96748	Kaunakakai	HI	73/100	90/100
10	96701	Aiea	HI	75/100	82/100
11	96704	Captain Cook	HI	75/100	73/100
12	96706	Ewa Beach	HI	75/100	60/100
13	96707	Kapolei	HI	75/100	73/100
14	96708	Haiku	HI	75/100	70/100
15	96740	Kailua Kona	HI	75/100	72/100
16	96746	Kapaa	HI	75/100	55/100
17	96750	Kealakekua	HI	75/100	73/100
18	96751	Kealia	HI	75/100	88/100
19	96753	Kihei	HI	75/100	72/100
20	96756	Koloa	HI	75/100	72/100
21	96773	Ninole	HI	75/100	88/100
22	96774	Ookala	HI	75/100	88/100
23	96779	Paia	HI	75/100	73/100
24	96782	Pearl City	HI	75/100	82/100
25	96797	Waipahu	HI	75/100	87/100
26	96853	J B P H H	HI	75/100	66/100
27	96703	Anahola	HI	80/100	77/100
28	96705	Eleele	HI	80/100	66/100
29	96710	Hakalau	HI	80/100	66/100
30	96712	Haleiwa	HI	80/100	55/100
31	96713	Hana	HI	80/100	87/100
32	96714	Hanalei	HI	80/100	72/100
33	96716	Hanapepe	HI	80/100	65/100
34	96717	Hauula	HI	80/100	60/100
35	96719	Hawi	HI	80/100	66/100
36	96722	Princeville	HI	80/100	82/100
37	96727	Honokaa	HI	80/100	73/100
38	96728	Honomu	HI	80/100	88/100
39	96730	Kaaawa	HI	80/100	60/100
40	96731	Kahuku	HI	80/100	87/100
41	96732	Kahului	HI	80/100	65/100
42	96734	Kailua	HI	80/100	55/100
43	96737	Ocean View	HI	80/100	66/100
44	96738	Waikoloa	HI	80/100	87/100
45	96741	Kalaheo	HI	80/100	87/100
46	96743	Kamuela	HI	80/100	71/100
47	96747	Kaumakani	HI	80/100	87/100
48	96749	Keaau	HI	80/100	73/100
49	96752	Kekaha	HI	80/100	77/100
50	96754	Kilauea	HI	80/100	82/100
51	96755	Kapaau	HI	80/100	66/100
52	96759	Kunia	HI	80/100	88/100
53	96760	Kurtistown	HI	80/100	73/100
54	96761	Lahaina	HI	80/100	85/100
55	96762	Laie	HI	80/100	77/100
56	96764	Laupahoehoe	HI	80/100	88/100
57	96765	Lawai	HI	80/100	73/100
58	96769	Makaweli	HI	80/100	73/100
59	96772	Naalehu	HI	80/100	66/100
60	96776	Paauilo	HI	80/100	88/100
61	96777	Pahala	HI	80/100	87/100
62	96778	Pahoa	HI	80/100	82/100
63	96780	Papaaloa	HI	80/100	73/100
64	96781	Papaikou	HI	80/100	88/100
65	96783	Pepeekeo	HI	80/100	88/100
66	96786	Wahiawa	HI	80/100	87/100
67	96789	Mililani	HI	80/100	73/100
68	96790	Kula	HI	80/100	95/100
69	96791	Waialua	HI	80/100	60/100
70	96792	Waianae	HI	80/100	55/100
71	96796	Waimea	HI	80/100	65/100
72	96813	Honolulu	HI	80/100	82/100
73	96814	Honolulu	HI	80/100	87/100
74	96815	Honolulu	HI	80/100	77/100
75	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.