Least Reliable Water Systems in Arizona — 2026

Out of 553 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	553
Lowest value	10/100
Median value	44/100
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	85172	Stanfield	AZ	20/100	50/100
3	85272	Stanfield	AZ	20/100	50/100
4	85325	Bouse	AZ	20/100	63/100
5	85328	Cibola	AZ	20/100	58/100
6	85934	Pinedale	AZ	22/100	82/100
7	85128	Coolidge	AZ	23/100	79/100
8	85228	Coolidge	AZ	23/100	79/100
9	85138	Maricopa	AZ	25/100	58/100
10	85139	Maricopa	AZ	25/100	58/100
11	85238	Maricopa	AZ	25/100	50/100
12	85239	Maricopa	AZ	25/100	58/100
13	85324	Black Canyon City	AZ	25/100	58/100
14	85348	Salome	AZ	25/100	65/100
15	85352	Tacna	AZ	25/100	58/100
16	85356	Wellton	AZ	25/100	53/100
17	85533	Clifton	AZ	25/100	49/100
18	85602	Benson	AZ	25/100	74/100
19	86023	Grand Canyon	AZ	25/100	60/100
20	86046	Williams	AZ	25/100	74/100
21	86301	Prescott	AZ	25/100	36/100
22	86302	Prescott	AZ	25/100	27/100
23	86303	Prescott	AZ	25/100	36/100
24	86304	Prescott	AZ	25/100	27/100
25	86305	Prescott	AZ	25/100	36/100
26	86313	Prescott	AZ	25/100	27/100
27	86327	Dewey	AZ	25/100	58/100
28	85141	Picacho	AZ	26/100	79/100
29	85241	Picacho	AZ	26/100	80/100
30	86015	Bellemont	AZ	27/100	78/100
31	85123	Arizona City	AZ	28/100	56/100
32	85132	Florence	AZ	28/100	79/100
33	85137	Kearny	AZ	28/100	70/100
34	85223	Arizona City	AZ	28/100	48/100
35	85232	Florence	AZ	28/100	78/100
36	85237	Kearny	AZ	28/100	65/100
37	85279	Florence	AZ	28/100	78/100
38	85534	Duncan	AZ	28/100	74/100
39	85540	Morenci	AZ	28/100	67/100
40	85546	Safford	AZ	28/100	68/100
41	85548	Safford	AZ	28/100	68/100
42	85621	Nogales	AZ	28/100	63/100
43	85628	Nogales	AZ	28/100	68/100
44	85662	Nogales	AZ	28/100	71/100
45	85928	Heber	AZ	28/100	73/100
46	86025	Holbrook	AZ	28/100	76/100
47	86343	Crown King	AZ	29/100	77/100
48	86438	Yucca	AZ	29/100	81/100
49	86512	Sanders	AZ	29/100	77/100
50	85001	Phoenix	AZ	30/100	58/100
51	85002	Phoenix	AZ	30/100	50/100
52	85003	Phoenix	AZ	30/100	58/100
53	85004	Phoenix	AZ	30/100	58/100
54	85005	Phoenix	AZ	30/100	58/100
55	85006	Phoenix	AZ	30/100	58/100
56	85007	Phoenix	AZ	30/100	53/100
57	85008	Phoenix	AZ	30/100	48/100
58	85009	Phoenix	AZ	30/100	53/100
59	85010	Phoenix	AZ	30/100	50/100
60	85011	Phoenix	AZ	30/100	50/100
61	85012	Phoenix	AZ	30/100	53/100
62	85013	Phoenix	AZ	30/100	48/100
63	85014	Phoenix	AZ	30/100	48/100
64	85015	Phoenix	AZ	30/100	48/100
65	85016	Phoenix	AZ	30/100	48/100
66	85017	Phoenix	AZ	30/100	53/100
67	85018	Phoenix	AZ	30/100	48/100
68	85019	Phoenix	AZ	30/100	53/100
69	85020	Phoenix	AZ	30/100	48/100
70	85021	Phoenix	AZ	30/100	48/100
71	85022	Phoenix	AZ	30/100	53/100
72	85023	Phoenix	AZ	30/100	53/100
73	85024	Phoenix	AZ	30/100	50/100
74	85025	Phoenix	AZ	30/100	50/100
75	85026	Phoenix	AZ	30/100	50/100
76	85027	Phoenix	AZ	30/100	58/100
77	85028	Phoenix	AZ	30/100	58/100
78	85029	Phoenix	AZ	30/100	53/100
79	85030	Phoenix	AZ	30/100	58/100
80	85031	Phoenix	AZ	30/100	48/100
81	85032	Phoenix	AZ	30/100	53/100
82	85033	Phoenix	AZ	30/100	53/100
83	85034	Phoenix	AZ	30/100	53/100
84	85035	Phoenix	AZ	30/100	58/100
85	85036	Phoenix	AZ	30/100	58/100
86	85037	Phoenix	AZ	30/100	58/100
87	85038	Phoenix	AZ	30/100	50/100
88	85039	Phoenix	AZ	30/100	50/100
89	85040	Phoenix	AZ	30/100	58/100
90	85041	Phoenix	AZ	30/100	53/100
91	85042	Phoenix	AZ	30/100	58/100
92	85043	Phoenix	AZ	30/100	58/100
93	85044	Phoenix	AZ	30/100	58/100
94	85045	Phoenix	AZ	30/100	50/100
95	85046	Phoenix	AZ	30/100	50/100
96	85048	Phoenix	AZ	30/100	58/100
97	85050	Phoenix	AZ	30/100	58/100
98	85051	Phoenix	AZ	30/100	53/100
99	85053	Phoenix	AZ	30/100	50/100
100	85054	Phoenix	AZ	30/100	58/100

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.