Idaho drinking water quality
Idaho has 2,020 active public water systems serving 1.8 million people. 1,310 of them, 65%, had at least one EPA violation in the past three years, 705 have an unresolved violation today, and 90 are designated serious violators by the EPA.
Active systems
2,020
in 44 counties
People served
1.8M
771 community systems serve 1.6M
Violations, past 3 years
1,310
65% of active systems
Serious violators
90
71 systems carry a health flag
Largest counties
All 44 counties| County | People served | Systems | With violations |
|---|---|---|---|
| Ada | 516,682 | 86 | 46 |
| Canyon | 219,459 | 142 | 105 |
| Kootenai | 181,138 | 193 | 106 |
| Bonneville | 138,851 | 134 | 82 |
| Bannock | 83,300 | 49 | 42 |
| Twin Falls | 76,266 | 56 | 44 |
| Madison | 50,546 | 33 | 21 |
| Latah | 41,383 | 35 | 23 |
| Bonner | 40,140 | 152 | 83 |
| Nez Perce | 39,959 | 25 | 14 |
Largest community water systems
All 2,020 systems| System | Serves | Status |
|---|---|---|
| Veolia Water Idaho Ada County |
264,978 | |
| Meridian Water Dept Ada County |
152,070 | |
| Nampa City of Canyon County |
100,200 | |
| Caldwell City of Canyon County |
78,740 | |
| Idaho Falls City of Bonneville County |
69,450 | |
| Pocatello City of Bannock County |
58,231 | |
| Twin Falls City of Twin Falls County |
56,121 | |
| Coeur D Alene City of Kootenai County |
54,115 | |
| Rexburg City of Madison County |
40,695 | |
| Kuna City of Ada County |
32,038 |
About the Idaho data
Retrieved from EPA ECHO on Oct 11, 2026. EPA records for Idaho systems do not include town names, so searches here match on ZIP code, street address, or county.