Total coliform in Idaho well water
In Idaho, 16% of 2,178 tested private well samples exceeded the EPA limit for total coliform (0 MPN/100mL).
Coliform bacteria live in soil and on plants as well as in sewage. Their presence means surface water or soil is getting into the well through the cap, casing or a nearby defect. Most coliforms are harmless, but they mean disease-causing organisms can get in the same way.
Check your total coliform number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes total coliform.
By county, from individual samples
Public monitoring samples against the EPA limit (0 MPN/100mL); counties with at least 30 samples.
| County | Samples | Detected | Above EPA limit | Median | Highest |
|---|---|---|---|---|---|
| Lincoln | 55 | 67% | 67% | 3 | 2,420 MPN/100mL |
| Nez Perce | 37 | 35% | 35% | 0 | 106 MPN/100mL |
| Fremont | 65 | 28% | 28% | 0 | 201 MPN/100mL |
| Minidoka | 44 | 25% | 25% | 0 | 2,420 MPN/100mL |
| Ada | 169 | 22% | 22% | 0 | 435 MPN/100mL |
| Owyhee | 120 | 18% | 18% | 0 | 579 MPN/100mL |
| Elmore | 73 | 18% | 18% | 0 | 1120 MPN/100mL |
| Jefferson | 63 | 16% | 16% | 0 | 8.6 MPN/100mL |
| Washington | 118 | 15% | 15% | 0 | 219 MPN/100mL |
| Payette | 329 | 15% | 15% | 0 | 150 MPN/100mL |
| Gem | 127 | 13% | 13% | 0 | 1046 MPN/100mL |
| Canyon | 604 | 12% | 12% | 0 | 727 MPN/100mL |
| Teton | 32 | 9% | 9% | 0 | 659 MPN/100mL |
| Twin Falls | 106 | 18% | 2% | 0 | 16 MPN/100mL |
| Kootenai | 48 | 0% | 0% | 0 | 0 MPN/100mL |
- Shoshone CCD, Lincoln County67% of 55
- Lewiston CCD, Nez Perce County37% of 35
- Kuna CCD, Ada County29% of 38
- Grand View CCD, Owyhee County27% of 44
- Ashton CCD, Fremont County27% of 37
- Nampa CCD, Canyon County24% of 116
- Wilder CCD, Canyon County23% of 30
- Boise City CCD, Ada County21% of 80
- Eagle CCD, Ada County21% of 43
- Payette CCD, Payette County17% of 30
- New Plymouth CCD, Payette County15% of 207
- Weiser CCD, Washington County15% of 118
- Melba CCD, Canyon County15% of 48
- Parma CCD, Canyon County14% of 86
- Mountain Home CCD, Elmore County14% of 58
- Mud Lake-Hamer CCD, Jefferson County14% of 51
- Emmett Bench CCD, Gem County12% of 122
- Fruitland CCD, Payette County12% of 92
- Caldwell CCD, Canyon County11% of 37
- Marsing CCD, Owyhee County11% of 47
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. total coliform counts and shares are listed on each county and town page with their sources.