Least Reliable Water Systems in Arizona — 2026

Out of 556 ZIP codes with data in Arizona, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Arizona Rankings

Statistic	Value
ZIP codes ranked	556
Lowest value	10/100
Median value	45/100
State	Arizona

100 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Reliability Score	Safety Score
1	85632	San Simon	AZ	10/100	58/100
2	85272	Stanfield	AZ	20/100	50/100
3	85325	Bouse	AZ	20/100	63/100
4	85328	Cibola	AZ	20/100	58/100
5	85228	Coolidge	AZ	23/100	79/100
6	85138	Maricopa	AZ	25/100	58/100
7	85139	Maricopa	AZ	25/100	58/100
8	85238	Maricopa	AZ	25/100	50/100
9	85239	Maricopa	AZ	25/100	58/100
10	85324	Black Canyon City	AZ	25/100	58/100
11	85348	Salome	AZ	25/100	65/100
12	85352	Tacna	AZ	25/100	58/100
13	85356	Wellton	AZ	25/100	53/100
14	85367	Yuma	AZ	25/100	64/100
15	85533	Clifton	AZ	25/100	49/100
16	85602	Benson	AZ	25/100	74/100
17	85707	Tucson	AZ	25/100	50/100
18	85708	Tucson	AZ	25/100	50/100
19	85737	Tucson	AZ	25/100	53/100
20	86023	Grand Canyon	AZ	25/100	60/100
21	86046	Williams	AZ	25/100	74/100
22	86327	Dewey	AZ	25/100	58/100
23	85141	Picacho	AZ	26/100	79/100
24	85241	Picacho	AZ	26/100	80/100
25	85934	Pinedale	AZ	27/100	82/100
26	86015	Bellemont	AZ	27/100	78/100
27	85132	Florence	AZ	28/100	79/100
28	85137	Kearny	AZ	28/100	70/100
29	85223	Arizona City	AZ	28/100	48/100
30	85232	Florence	AZ	28/100	78/100
31	85237	Kearny	AZ	28/100	65/100
32	85279	Florence	AZ	28/100	78/100
33	85534	Duncan	AZ	28/100	74/100
34	85540	Morenci	AZ	28/100	67/100
35	85546	Safford	AZ	28/100	68/100
36	85548	Safford	AZ	28/100	68/100
37	85621	Nogales	AZ	28/100	63/100
38	85628	Nogales	AZ	28/100	68/100
39	85662	Nogales	AZ	28/100	71/100
40	86025	Holbrook	AZ	28/100	76/100
41	86343	Crown King	AZ	29/100	77/100
42	86438	Yucca	AZ	29/100	81/100
43	86512	Sanders	AZ	29/100	77/100
44	85301	Glendale	AZ	30/100	67/100
45	85302	Glendale	AZ	30/100	67/100
46	85303	Glendale	AZ	30/100	72/100
47	85304	Glendale	AZ	30/100	67/100
48	85305	Glendale	AZ	30/100	69/100
49	85306	Glendale	AZ	30/100	67/100
50	85307	Glendale	AZ	30/100	69/100
51	85308	Glendale	AZ	30/100	67/100
52	85310	Glendale	AZ	30/100	72/100
53	85311	Glendale	AZ	30/100	69/100
54	85312	Glendale	AZ	30/100	69/100
55	85318	Glendale	AZ	30/100	69/100
56	85364	Yuma	AZ	30/100	54/100
57	85365	Yuma	AZ	30/100	64/100
58	85366	Yuma	AZ	30/100	59/100
59	85369	Yuma	AZ	30/100	59/100
60	85610	Elfrida	AZ	30/100	66/100
61	85701	Tucson	AZ	30/100	58/100
62	85702	Tucson	AZ	30/100	50/100
63	85703	Tucson	AZ	30/100	50/100
64	85704	Tucson	AZ	30/100	58/100
65	85705	Tucson	AZ	30/100	53/100
66	85706	Tucson	AZ	30/100	58/100
67	85709	Tucson	AZ	30/100	50/100
68	85710	Tucson	AZ	30/100	53/100
69	85711	Tucson	AZ	30/100	58/100
70	85712	Tucson	AZ	30/100	53/100
71	85713	Tucson	AZ	30/100	58/100
72	85714	Tucson	AZ	30/100	58/100
73	85715	Tucson	AZ	30/100	53/100
74	85716	Tucson	AZ	30/100	53/100
75	85717	Tucson	AZ	30/100	50/100
76	85718	Tucson	AZ	30/100	53/100
77	85719	Tucson	AZ	30/100	53/100
78	85720	Tucson	AZ	30/100	50/100
79	85721	Tucson	AZ	30/100	50/100
80	85722	Tucson	AZ	30/100	50/100
81	85723	Tucson	AZ	30/100	50/100
82	85724	Tucson	AZ	30/100	50/100
83	85725	Tucson	AZ	30/100	50/100
84	85726	Tucson	AZ	30/100	50/100
85	85728	Tucson	AZ	30/100	50/100
86	85730	Tucson	AZ	30/100	58/100
87	85731	Tucson	AZ	30/100	50/100
88	85732	Tucson	AZ	30/100	50/100
89	85733	Tucson	AZ	30/100	50/100
90	85734	Tucson	AZ	30/100	50/100
91	85735	Tucson	AZ	30/100	53/100
92	85736	Tucson	AZ	30/100	50/100
93	85740	Tucson	AZ	30/100	50/100
94	85741	Tucson	AZ	30/100	58/100
95	85742	Tucson	AZ	30/100	53/100
96	85743	Tucson	AZ	30/100	58/100
97	85744	Tucson	AZ	30/100	50/100
98	85745	Tucson	AZ	30/100	53/100
99	85746	Tucson	AZ	30/100	58/100
100	85747	Tucson	AZ	30/100	53/100

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: 2026-06-04.

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.