Idaho Water Quality — 139 Cities Tested

Analysis

Idaho water quality overview

Idaho's drinking water quality is fair overall, with an average score of 68.2 out of 100 across 139 cities tested. The median score is 73.3, serving a total population of 1,562,349 residents. 40% of cities scored a D or F, pointing to significant water quality challenges in parts of the state. PFAS "forever chemicals" were detected in 37 of 139 cities tested (27%). 3 cities exceed the 2024 EPA maximum contaminant levels. 3 cities have lead levels exceeding the EPA action level of 15 ppb, often indicating aging infrastructure with lead service lines or lead solder. The state relies on a mix of water sources: 118 cities use groundwater while 21 draw from surface water such as rivers, lakes, and reservoirs.

Key Concerns

Issues to watch in Idaho

37 cities

PFAS Detected

27% of tested cities have PFAS in their water supply.

3 cities

Lead Exceedances

Lead levels above the EPA action level of 15 ppb (90th percentile).

134 cities

Health Violations

35,478 total violations recorded, 133 with unresolved issues.

17 cities

Failing Systems

Received a grade of F, indicating serious water quality issues.

Contaminant Data

Explore contaminants in Idaho

Lead in Idaho → Ranked by 90th percentile level (ppb) PFAS in Idaho → Ranked by compounds detected Copper in Idaho → Ranked by 90th percentile level (mg/L)

More contaminants tested in Idaho

HAA5 → Chromium-6 → Arsenic → Nitrate → Strontium → 1,4-Dioxane → Manganese → Vanadium → Chlorate → Molybdenum → Cobalt → Lithium →

State context

9

Superfund sites in Idaho

EPA National Priorities List

31.4%

of Idaho residents on fluoridated water

CDC, 2020

5,040,020

lbs released to surface water

Top 10 TRI facilities, 2023

14.8%

of Idaho domestic wells exceed EPA arsenic limit

USGS, 10,302 samples · 10 µg/L MCL

Domestic well chemistry

Private-well water in Idaho

Based on USGS Powell Domestic-Well Database — 6,194 private wells sampled across Idaho. These wells are not regulated by the EPA; if you draw your tap from a private well, the public-system grade above does not apply to you.

2.3 µg/L

Median arsenic in domestic wells

P90 14.3 µg/L · max 950.0 µg/L

3 µg/L

Median manganese in domestic wells

6.2% exceed 300 µg/L aesthetic limit

Industrial pollution

Top industrial water polluters in Idaho

Industrial polluters nearby

The 10 facilities reporting the most pounds released to surface water in Idaho, 2023.

Total reported releases to surface water: 5,040,020 lbs

Facility	Top chemical	To surface water (lbs/yr)
MCCAIN FOODS USA INC. Food · MCCAIN FOODS USA INC BURLEY, ID83318	Nitrate compounds (water dissociable; reportable only when in aqueous solution)	4,938,764
CLEARWATER PAPER CORP-PPD & CPD IDAHO Paper · CLEARWATER PAPER CORP LEWISTON, ID83501	Methanol	66,488
THOMPSON CREEK MINING CO Metal Mining · THOMPSON CREEK METALS CO CLAYTON, ID83227	Nitrate compounds (water dissociable; reportable only when in aqueous solution)	29,253
US EPA FUND-LEAD SUPERFUND SITE/BUNKER HILL CTP Other · US ENVIRONMENTAL PROTECTION AGENCY KELLOGG, ID83837	Manganese compounds	3,718
HECLA LTD LUCKY FRIDAY MINE UNIT Metal Mining · HECLA MINING CO MULLAN, ID83846	Manganese And Manganese Compounds	860

+ 5 more facilities

Source: EPA Toxic Release Inventory (TRI) 2023

Test your own tap

Get your Idaho water tested

City-level data shows the source and infrastructure picture — but lead and other home-plumbing issues only show up at your tap. Find a state-certified lab, see what to test for, and what it costs.

Grade Distribution

How Idaho cities scored

A: 44 B: 29 C: 10 D: 39 F: 17

Best Cities

Worst Cities

City Map

Water quality across Idaho

Each dot is a city, colored by its water quality grade. Size reflects population served. Click any city to view its full water report.

All Cities

139 cities in Idaho

Full rankings →

#	City	Grade	Score	Population	Violations
1	Shoshone	A+	96.4	1K	8
2	Firth	A+	96.1	511	10
3	Kooskia	A	94.5	607	9
4	Star	A	94.2	14K	26
5	Wendell	A	93.9	3K	40
6	Council	A	93.8	900	32
7	Teton	A	93.5	735	52
8	Aberdeen	A	93.3	2K	20
9	Dalton Gardens	A	93.1	3K	19
10	Malad	A	92.9	2K	21
11	Greenleaf	A	92.9	846	44
12	Paul	A	92.6	1K	14
13	Mackay	A	92.2	566	31
14	Downey	A	92.1	625	71
15	Deary	A	92	529	20
16	Uconn	A	91.9	680	10
17	Craigmont	A	91.5	501	54
18	Weippe	A	91.4	527	14
19	Wilder	A	91.3	4K	31
20	Hauser	A	91.2	1K	37
21	Dubois	A	90.8	511	17
22	Sugar City	A	90.1	3K	43
23	Bayview	A	90.1	1K	31
24	Hagerman	A	90.1	1K	47
25	Carey	A-	89.8	993	36
26	Mccammon	A-	89.8	800	25
27	Glenns Ferry	A-	89.3	1K	33
28	Wallace	A-	88.9	3K	14
29	Riggins	A-	88.9	554	62
30	Weiser	A-	88.7	6K	41
31	Pinehurst	A-	88.7	2K	81
32	Clark Fork	A-	88.5	730	22
33	Kingston	A-	88.4	1K	46
34	Genesee	A-	88.3	1K	59
35	Hope	A-	88.3	537	50
36	Richfield	A-	88	501	38
37	Fish Haven	A-	87.8	750	49
38	Ririe	A-	87.5	656	37
39	Roberts	A-	87.2	680	61
40	Iona	A-	87.1	3K	72
41	Blanchard	A-	87.1	1K	65
42	Montpelier	A-	86.7	3K	21
43	Ashton	A-	86	1K	57
44	Arco	A-	85.4	1K	65
45	Paris	B+	84.4	535	15
46	Coolin	B+	84.3	632	50
47	Ovid	B+	84.1	658	76
48	Old Town	B+	82.9	545	46
49	Gooding	B+	82.8	4K	118
50	Cascade	B+	82.6	1K	20
51	Melba	B+	82.3	636	122
52	Cottonwood	B+	82.2	2K	102
53	Kimberly	B+	81.9	5K	91
54	Homedale	B+	81.2	3K	76
55	Inkom	B+	80.6	844	48
56	Payette	B	79.8	8K	186
57	Dayton	B	79.5	560	48
58	New Meadows	B	79.1	1K	125
59	Priest River	B	78.3	2K	143
60	Hansen	B	77.1	1K	11
61	Challis	B	76.9	1K	134
62	Potlatch	B	76.8	1K	48
63	Donnelly	B	76	816	114
64	Fernwood	B	75.9	645	162
65	Moyie Springs	B	75.8	1K	126
66	Hazelton	B	75.7	954	199
67	Dover	B-	74.6	865	11
68	Grace	B-	73.5	1K	151
69	Victor	B-	73.4	2K	110
70	St Maries	B-	73.3	5K	129
71	Idaho City	B-	71.9	641	160
72	Filer	B-	70.8	3K	84
73	Grangeville	B-	70.5	3K	100
74	Kellogg	C+	68.6	6K	204
75	Troy	C+	67.7	900	218
76	Soda Springs	C+	66.7	3K	144
77	Chubbuck	C+	66.2	16K	93
78	Franklin	C+	66.2	6K	120
79	Notus	C	62.9	1K	312
80	Hailey	C	61.1	9K	108
81	Garden City	C-	59.8	13K	270
82	Horseshoe Bend	C-	57.6	801	184
83	Moscow	C-	55	35K	130
84	Twin Falls	D+	52.5	56K	313
85	Ucon	D+	52	1K	193
86	Middleton	D+	51.6	14K	310
87	Rupert	D+	51.2	6K	121
88	Ammon	D+	50.2	17K	329
89	Athol	D+	50	4K	341
90	Driggs	D+	50	4K	240
91	Spirit Lake	D+	50	4K	239
92	New Plymouth	D+	50	2K	456
93	Marsing	D+	50	1K	297
94	Lapwai	D+	50	1K	850
95	Orofino	D	49.8	5K	174
96	Juliaetta	D	49.7	624	56
97	Jerome	D	49.2	14K	226
98	Rigby	D	49.2	7K	305
99	Ketchum	D	49.2	5K	325
100	Sun Valley	D	49	4K	192
101	Fort Hall	D	48.8	3K	504
102	Kuna	D	48.2	33K	617
103	Mountain Home	D	48.2	16K	944
104	Shelley	D	48.2	5K	280
105	Sagle	D	48	2K	311
106	Fruitland	D	47.8	7K	349
107	Mountain Home Afb	D	47.5	8K	232
108	Buhl	D	47.2	5K	209
109	St Anthony	D	47.2	4K	206
110	Heyburn	D	47.1	3K	169
111	Bonners Ferry	D	47	10K	1001
112	Bellevue	D	47	3K	120
113	Kamiah	D	47	2K	408
114	Idaho Falls	D	46.6	97K	1042
115	Oakley	D	46.5	1K	154
116	Post Falls	D	46	42K	486
117	Garden Valley	D	46	1K	518
118	Rathdrum	D	45.5	25K	704
119	Emmett	D	45.2	7K	386
120	Hayden	D	45	22K	369
121	Burley	F	45	11K	362
122	Coeur D'Alene	D	45	5K	446
123	Salmon	D	45	4K	314
124	Lewiston	F	44.2	36K	522
125	Coeur D Alene	F	44	57K	629
126	Sandpoint	F	44	18K	909
127	Mccall	F	44	5K	161
128	Plummer	F	44	2K	1001
129	Eagle	F	43.2	13K	583
130	American Falls	F	43.2	5K	232
131	Rexburg	F	43.1	42K	848
132	Meridian	F	42.9	149K	327
133	Pocatello	F	42.5	60K	1261
134	Blackfoot	F	42.5	13K	575
135	Nampa	F	41.8	105K	2009
136	Preston	F	41	13K	943
137	Caldwell	F	38.5	78K	1720
138	Worley	F	36	1K	138
139	Boise	F	33.6	286K	2299

Counties

Browse Idaho counties

Ada 6 cities · avg 53.6 Adams 2 cities · avg 86.4 Bannock 5 cities · avg 74.2 Bear Lake 3 cities · avg 86.3 Benewah 3 cities · avg 64.4 Bingham 4 cities · avg 70 Blaine 5 cities · avg 59.2 Boise 3 cities · avg 58.5 Bonner 9 cities · avg 75.1 Bonneville 5 cities · avg 65.6 Boundary 2 cities · avg 61.4 Butte 1 city · avg 85.4 Cache 1 city · avg 66.2 Canyon 7 cities · avg 65.9 Caribou 2 cities · avg 70.1 Cassia 2 cities · avg 45.8 Clark 1 city · avg 90.8 Clearwater 2 cities · avg 70.6 Custer 2 cities · avg 84.6 Elmore 3 cities · avg 61.7 Franklin 2 cities · avg 60.3 Fremont 3 cities · avg 75.6 Gem 1 city · avg 45.2 Gooding 3 cities · avg 88.9 Idaho 4 cities · avg 84 Jefferson 3 cities · avg 74.6 Jerome 2 cities · avg 62.5 Kootenai 11 cities · avg 57.8 Latah 6 cities · avg 71.6 Lemhi 1 city · avg 45 Lewis 2 cities · avg 69.3 Lincoln 2 cities · avg 92.2 Madison 2 cities · avg 66.6 Minidoka 3 cities · avg 63.6 Nez Perce 2 cities · avg 47.1 Oneida 1 city · avg 92.9 Owyhee 2 cities · avg 65.6 Payette 3 cities · avg 59.2 Power 1 city · avg 43.2 Rich 1 city · avg 84.1 Shoshone 4 cities · avg 83.7 Teton 2 cities · avg 61.7 Twin Falls 5 cities · avg 65.9 Valley 3 cities · avg 67.5 Washington 1 city · avg 88.7

ZIP Codes

Browse Idaho by ZIP code

Look up water quality by ZIP code to find the systems serving your area.

View all Idaho ZIP codes →

FAQ

Frequently asked questions about Idaho's water

Is Idaho's tap water safe to drink?

Idaho's water quality varies by city. The statewide average grade is C+ (68.2/100). 53% of cities scored an A or B, while 40% received a D or F. Check your specific city for detailed results.

Which Idaho cities have the best water quality?

The top-rated cities are Shoshone (A+), Firth (A+), Kooskia (A). These cities scored highest based on violation history, lead levels, PFAS contamination, and regulatory compliance.

Which Idaho cities have the worst water quality?

The lowest-rated cities are Boise (F), Worley (F), Caldwell (F). We recommend residents in these areas consider water filtration and review their city's specific contaminant data.

How many Idaho cities have PFAS in their water?

37 out of 139 cities tested positive for PFAS "forever chemicals" (27%). 3 cities exceed the 2024 EPA maximum contaminant levels. Reverse osmosis or activated carbon filters can help reduce PFAS exposure.

Do any Idaho cities have dangerous lead levels?

3 cities exceed the EPA lead action level of 15 ppb. Lead contamination typically comes from aging pipes and lead service lines rather than the water source itself. An NSF 53-certified filter can effectively remove lead from tap water.

Idaho Water Quality Report