Idaho Water Quality
Drinking water data for all 44 counties.
Avg Water Score
32.6
State Grade
F
Counties with Data
44
of 44 total
All Idaho Counties
| County | Water Score |
|---|---|
| Adams County | 86.0 |
| Custer County | 86.0 |
| Oneida County | 86.0 |
| Shoshone County | 86.0 |
| Washington County | 86.0 |
| Nez Perce County | 61.5 |
| Ada County | 55.6 |
| Bannock County | 53.8 |
| Twin Falls County | 52.8 |
| Gem County | 51.2 |
| Bear Lake County | 48.5 |
| Minidoka County | 48.4 |
| Jerome County | 47.6 |
| Bonneville County | 44.7 |
| Gooding County | 38.3 |
| Caribou County | 36.7 |
| Lincoln County | 35.8 |
| Teton County | 35.7 |
| Kootenai County | 35.5 |
| Canyon County | 31.8 |
| Benewah County | 27.4 |
| Bingham County | 25.9 |
| Owyhee County | 19.8 |
| Bonner County | 19.7 |
| Butte County | 18.7 |
| Blaine County | 18.1 |
| Madison County | 17.5 |
| Jefferson County | 17.4 |
| Payette County | 16.4 |
| Latah County | 16.2 |
| Cassia County | 15.9 |
| Clearwater County | 15.9 |
| Elmore County | 14.8 |
| Camas County | 13.4 |
| Power County | 12.2 |
| Lemhi County | 9.2 |
| Lewis County | 9.1 |
| Clark County | 8.7 |
| Franklin County | 8.0 |
| Valley County | 6.3 |
| Boise County | 5.7 |
| Idaho County | 3.7 |
| Fremont County | 3.3 |
| Boundary County | 3.1 |
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Frequently Asked Questions
Which county in Idaho has the best water quality?
Adams County has the highest water quality score in Idaho at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Idaho has the most water violations?
Boundary County has among the lowest water quality scores in Idaho at 3.1/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Idaho?
Idaho has an average water quality score of 32.6/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in Idaho water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.
Data Source
Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.
Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.