Idaho Tap Water Quality Report

227 cities analyzed • 1,204,044 people served

Updated March 2026 • Data from EWG & EPA SDWIS

227

Cities Analyzed

3.4

Avg Above Guidelines

1,204,044

Total Population Served

Best Water Quality

Cascade (0 above guidelines)

Most Concerns

Boise (16 above guidelines)

Most Common Contaminants in Idaho

Contaminant	Found In	% of Cities
Nitrate carcinogen	161 of 227	71%
Uranium carcinogen	122 of 227	54%
Total trihalomethanes (TTHMs) carcinogen	103 of 227	45%
Radium, combined (-226 and -228)	102 of 227	45%
Haloacetic acids (HAA5) carcinogen	70 of 227	31%
Barium	67 of 227	30%
Arsenic carcinogen	66 of 227	29%
Fluoride	66 of 227	29%
Nitrate and nitrite carcinogen	44 of 227	19%
Manganese	23 of 227	10%

City-by-City Water Quality Rankings

Ranked by number of contaminants above EWG health guidelines (most to fewest).

#	City	Detected	Above Guidelines	Above Legal	People Served
1	Boise	35	16	0	250,799
2	Twin Falls	19	15	0	50,197
3	Mountain Home	24	15	0	14,000
4	Meridian	30	13	0	138,620
5	Idaho Falls	22	13	0	69,450
6	Kuna	21	13	0	32,038
7	Nampa	22	12	0	100,200
8	Garden City	28	12	0	12,500
9	Weiser	13	11	0	5,630
10	Mountain Home Afb	18	10	0	7,500
11	Marsing	11	10	0	1,300
12	Glenns Ferry	10	10	0	0
13	Chubbuck	16	9	0	15,842
14	Idaho City	19	9	0	478
15	Coeur D Alene	15	8	0	54,115
16	Burley	13	8	0	10,345
17	Pocatello	16	7	0	57,092
18	Jerome	7	7	0	11,500
19	Horseshoe Bend	7	7	0	750
20	Donnelly	9	7	0	237
21	Hollister	7	7	0	220
22	Yellow Pine	7	7	0	72
23	Juliaetta	13	7	0	0
24	Rexburg	16	6	0	39,409
25	Star	12	6	0	14,000
26	Blackfoot	12	6	0	11,922
27	Mccall	7	6	0	3,871
28	Bonners Ferry	9	6	0	3,367
29	Challis	7	6	0	900
30	Troy	7	6	0	850
31	Melba	6	6	0	576
32	Atlanta	8	6	0	91
33	Paso Robles	6	6	0	50
34	Greenleaf	9	6	0	0
35	Kimberley	8	6	0	0
36	Filer	9	6	0	0
37	Castleford	6	6	0	0
38	Murtaugh	7	6	0	0
39	Hansen	7	6	0	0
40	Caldwell	13	5	0	65,000
41	Post Falls	9	5	0	17,422
42	Ammon	13	5	0	17,338
43	Rathdrum	8	5	0	8,108
44	Hailey	5	5	0	8,000
45	Shelley	10	5	0	4,409
46	St Maries	7	5	0	4,038
47	Spirit Lake	7	5	0	2,650
48	Dalton Gardens	5	5	0	2,528
49	Priest River	6	5	0	1,773
50	Driggs	7	5	0	1,300
51	Genesee	9	5	0	1,044
52	Minidoka	8	5	0	120
53	Anderson	5	5	0	81
54	Spokane Valley	6	5	0	50
55	Dayton	6	5	0	0
56	Craigmont	7	5	0	0
57	Lewiston	11	4	0	20,000
58	Emmett	6	4	0	6,700
59	Hauser	4	4	0	1,350
60	Athol	4	4	0	1,104
61	Hagerman	4	4	0	981
62	Coeur D'alene	4	4	0	875
63	Oakley	4	4	0	821
64	Inkom	7	4	0	792
65	Moyie Springs	5	4	0	775
66	Old Town	5	4	0	623
67	Lava Hot Springs	8	4	0	442
68	Orange	7	4	0	108
69	Los Altos	4	4	1	98
70	Kimberly	6	4	0	70
71	Gooding	4	4	0	60
72	Spokane	4	4	0	58
73	Swan Valley	7	4	0	54
74	Buhl	4	4	0	54
75	Picabo	4	4	0	50
76	Wendell	6	4	0	0
77	Ashton	4	4	0	0
78	Kendrick	6	4	0	0
79	Shoshone	4	4	0	0
80	Bellevue	4	4	0	0
81	Peck	4	4	0	0
82	Winchester	8	4	0	0
83	Weston	4	4	0	0
84	Albion	5	4	0	0
85	Moscow	10	3	0	26,000
86	Hayden	3	3	0	9,375
87	Middleton	10	3	0	8,645
88	Rigby	7	3	0	5,400
89	Eagle	6	3	0	4,989
90	Iona	5	3	0	2,717
91	Wilder	5	3	0	1,579
92	Sugar City	6	3	0	1,567
93	Sun Valley	6	3	0	1,500
94	Ucon	3	3	0	1,161
95	Teton	3	3	0	735
96	Ririe	5	3	0	656
97	Downey	3	3	0	625
98	Mackay	6	3	0	566
99	Riggins	7	3	0	434
100	Cottonwood	6	3	0	425
101	Eden	3	3	0	411
102	Moreland	3	3	0	364
103	Newdale	3	3	0	340
104	Sagle	4	3	0	318
105	Declo	3	3	0	300
106	Elk City	4	3	0	220
107	Elk River	5	3	0	165
108	Lenore	3	3	0	100
109	King Hill	4	3	1	87
110	Laketown	3	3	0	64
111	Gannett	4	3	0	60
112	Arco	3	3	0	59
113	Hazelton	3	3	0	55
114	Richfield	5	3	0	0
115	Ferdinand	6	3	0	0
116	Ahsahka	3	3	0	0
117	Bliss	3	3	0	0
118	Rogerson	3	3	0	0
119	Roberts	3	3	0	0
120	Avery	4	3	0	0
121	Lapwai	5	3	0	0
122	Tetonia	4	3	0	0
123	Orem	6	3	0	0
124	Sandpoint	3	2	0	12,003
125	Preston	3	2	0	5,591
126	St Anthony	3	2	0	3,606
127	Salmon	2	2	1	3,158
128	Montpelier	3	2	0	2,772
129	Wallace	2	2	0	2,388
130	Malad	2	2	0	2,200
131	Parma	3	2	0	2,147
132	Aberdeen	2	2	0	2,088
133	Orofino	2	2	0	2,000
134	Plummer	4	2	0	1,028
135	Fish Haven	4	2	0	1,000
136	Mccammon	5	2	0	800
137	Dover	4	2	0	600
138	Worley	3	2	0	591
139	Notus	2	2	0	539
140	Firth	2	2	0	511
141	Georgetown	2	2	0	476
142	Hope	4	2	0	445
143	Stites	4	2	0	253
144	Soda Springs	2	2	0	250
145	Harrison	3	2	0	195
146	Ribgy	5	2	0	193
147	Fernwood	2	2	0	150
148	Kamiah	3	2	0	150
149	Port Orchard	2	2	0	129
150	Grand View	2	2	0	100
151	Grangeville	2	2	0	89
152	Viola	2	2	0	78
153	Franklin	2	2	0	75
154	Ponderay	3	2	0	70
155	Rockland	2	2	0	60
156	Priest Lake	3	2	0	50
157	Coolin	3	2	0	48
158	Springfield	2	2	0	35
159	Atomic City	5	2	0	35
160	Pierce	2	2	0	25
161	Clark Fork	2	2	0	0
162	Culdesac	2	2	0	0
163	Carey	3	2	0	0
164	Dietrich	2	2	0	0
165	Clifton	4	2	0	0
166	Bancroft	2	2	0	0
167	Cataldo	2	2	0	0
168	Bayview	3	2	0	0
169	Bovill	4	2	0	0
170	Homedale	1	1	0	2,600
171	New Meadows	1	1	0	800
172	Kingston	1	1	0	570
173	Arimo	2	1	0	368
174	Parker	1	1	0	322
175	Garden Valley	2	1	0	305
176	Bennington	2	1	0	250
177	American Falls	2	1	0	200
178	Moore	1	1	0	196
179	Provo	3	1	0	175
180	Blanchard	1	1	0	155
181	Richland	1	1	0	120
182	Rupert	2	1	0	100
183	Seattle	1	1	0	90
184	Kellogg	1	1	0	85
185	Harvard	3	1	0	82
186	Clearwater	3	1	0	80
187	Calder	1	1	0	80
188	Pinehurst	3	1	0	80
189	Murphy	1	1	0	75
190	Williamsburg	1	1	0	75
191	St Paul	2	1	0	70
192	Fruitland	3	1	0	70
193	Wellton	1	1	0	65
194	San Diego	1	1	0	60
195	Howe	1	1	0	55
196	Bountiful	1	1	0	50
197	Princeton	1	1	0	40
198	Fenn	1	1	0	30
199	Medimont	4	1	0	27
200	Indian Valley	1	1	0	26
201	Paul	2	1	0	0
202	Dubois	1	1	0	0
203	Weippe	1	1	0	0
204	Nezperce	1	1	0	0
205	Deary	5	1	0	0
206	Council	1	1	0	0
207	Reubens	1	1	0	0
208	Kooskia	2	1	0	0
209	Cascade	1	0	0	1,000
210	Potlatch	1	0	0	812
211	Paris	1	0	0	479
212	New Plymouth	5	0	0	475
213	Ketchum	1	0	0	450
214	Fairfield	1	0	0	441
215	Monteview	0	0	0	358
216	Jackson	0	0	0	210
217	St. Charles	0	0	0	191
218	Tensed	0	0	0	123
219	White Bird	4	0	0	106
220	Heyburn	0	0	0	100
221	Grace	0	0	0	90
222	Victor	0	0	0	90
223	Bruneau	1	0	0	88
224	Clarkia	1	0	0	53
225	Murray	1	0	0	35
226	Bloomington	1	0	0	0
227	Cambridge	1	0	0	0

Recommended Filtration for Idaho

Based on the most common contaminants found across Idaho (Nitrate, Uranium, Total trihalomethanes (TTHMs)), we recommend a reverse osmosis system or high-quality carbon block filter to remove disinfection byproducts and their precursors.

Echo RO System

Removes up to 99.9% of contaminants. The gold standard for drinking water in Idaho homes.

View RO Systems

Echo Whole-Home Filter

Protect every tap in your home from chlorine, VOCs, and disinfection byproducts.

View Whole-Home Filters

Echo Hydrogen Water Flask

Once your water is clean, supercharge it with molecular hydrogen for antioxidant and anti-inflammatory benefits.

Shop Hydrogen Flask

Frequently Asked Questions

Is Idaho tap water safe to drink?

Water quality varies significantly across Idaho. Of the 227 cities analyzed, the average city has 3.4 contaminants above EWG health guidelines. The best water quality was found in Cascade. We recommend checking your specific city's report for detailed information.

What city has the best water in Idaho?

Based on our analysis, Cascade has the fewest contaminants above EWG health guidelines in Idaho, with 0 above guideline levels.

What city has the worst water in Idaho?

Based on our analysis, Boise has the most contaminants above EWG health guidelines in Idaho, with 16 above guideline levels.

What's the best water filter for Idaho residents?

For most Idaho households, we recommend a reverse osmosis (RO) system for drinking water and a whole-home filter for showers and baths. The specific recommendation depends on your city's contaminant profile — check your city's report for personalized guidance.

National Water Quality Reports

Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)

Last updated: March 2026

Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.

Idaho Water Quality Report (2026)