Least Reliable Water Systems in Idaho — 2026

Out of 324 ZIP codes with data in Idaho, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Idaho Rankings

Statistic	Value
ZIP codes ranked	324
Lowest value	10/100
Median value	55/100
State	Idaho

100 Lowest-Ranked ZIP Codes

Rank	ZIP Code	City	State	Reliability Score	Safety Score
1	83633	King Hill	ID	10/100	33/100
2	83619	Fruitland	ID	15/100	58/100
3	83655	New Plymouth	ID	18/100	67/100
4	83541	Lenore	ID	19/100	84/100
5	83631	Idaho City	ID	19/100	64/100
6	83876	Worley	ID	21/100	59/100
7	83520	Ahsahka	ID	22/100	62/100
8	83546	Pierce	ID	22/100	41/100
9	83624	Grand View	ID	22/100	79/100
10	83263	Preston	ID	24/100	81/100
11	83271	Rockland	ID	24/100	81/100
12	83316	Buhl	ID	24/100	77/100
13	83318	Burley	ID	24/100	77/100
14	83336	Heyburn	ID	24/100	78/100
15	83211	American Falls	ID	25/100	55/100
16	83535	Juliaetta	ID	25/100	12/100
17	83610	Cambridge	ID	25/100	88/100
18	83638	Mccall	ID	25/100	58/100
19	83677	Yellow Pine	ID	25/100	52/100
20	83834	Harvard	ID	25/100	41/100
21	83874	Murray	ID	25/100	59/100
22	83327	Fairfield	ID	27/100	61/100
23	83353	Sun Valley	ID	27/100	64/100
24	83501	Lewiston	ID	27/100	94/100
25	83346	Oakley	ID	28/100	78/100
26	83313	Bellevue	ID	29/100	62/100
27	83350	Rupert	ID	30/100	73/100
28	83524	Culdesac	ID	30/100	91/100
29	83536	Kamiah	ID	30/100	59/100
30	83605	Caldwell	ID	30/100	65/100
31	83607	Caldwell	ID	30/100	65/100
32	83616	Eagle	ID	30/100	68/100
33	83629	Horseshoe Bend	ID	30/100	50/100
34	83836	Hope	ID	30/100	58/100
35	83639	Marsing	ID	31/100	79/100
36	83344	Murtaugh	ID	32/100	55/100
37	83438	Parker	ID	32/100	65/100
38	83845	Moyie Springs	ID	32/100	61/100
39	83864	Sandpoint	ID	32/100	64/100
40	83660	Parma	ID	33/100	69/100
41	83237	Franklin	ID	34/100	81/100
42	83328	Filer	ID	34/100	81/100
43	83647	Mountain Home	ID	34/100	65/100
44	83314	Bliss	ID	35/100	60/100
45	83467	Salmon	ID	35/100	52/100
46	83632	Indian Valley	ID	35/100	60/100
47	83656	Notus	ID	35/100	75/100
48	83702	Boise	ID	36/100	69/100
49	83703	Boise	ID	36/100	74/100
50	83704	Boise	ID	36/100	72/100
51	83705	Boise	ID	36/100	72/100
52	83706	Boise	ID	36/100	69/100
53	83709	Boise	ID	36/100	74/100
54	83712	Boise	ID	36/100	74/100
55	83713	Boise	ID	36/100	72/100
56	83716	Boise	ID	36/100	55/100
57	83338	Jerome	ID	37/100	82/100
58	83440	Rexburg	ID	37/100	82/100
59	83401	Idaho Falls	ID	38/100	73/100
60	83402	Idaho Falls	ID	38/100	73/100
61	83404	Idaho Falls	ID	38/100	73/100
62	83406	Idaho Falls	ID	38/100	73/100
63	83525	Elk City	ID	38/100	38/100
64	83226	Challis	ID	40/100	51/100
65	83340	Ketchum	ID	40/100	44/100
66	83348	Picabo	ID	40/100	62/100
67	83552	Stites	ID	40/100	66/100
68	83623	Glenns Ferry	ID	40/100	56/100

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.