Well water in Teton County, Idaho
In Teton County, 9% of 32 tested well samples exceeded the EPA limit for total coliform (0 MPN/100mL), based on public data from Idaho statewide ground water quality monitoring (IDWR EDMS) and USGS Water Quality Portal.
143 individual samples from 67 wells, 1979 to 2025. Data refreshed September 9, 2026.
What individual samples found
Each row summarizes every public sample for that contaminant inside Teton County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Total coliform 2013 to 2021 | 32 | 9% | 9% | 0 | 659 | 0 MPN/100mL EPA limit | |
| E. coli 1991 to 2008 | 143 | 3% | 3% | 0 | 5 | 0 MPN/100mL EPA limit | |
| Arsenic 1991 to 2025 | 91 | 34% | 0% | 0 | 9.1 | 10 ug/L EPA limit | |
| Fluoride 1979 to 2025 | 89 | 45% | 0% | 0 | 0.46 | 4 mg/L EPA limit | |
| Nitrate 1979 to 2025 | 82 | 95% | 0% | 0.61 | 8.04 | 10 mg/L EPA limit | |
| Nitrite 1991 to 2021 | 58 | 9% | 0% | 0 | 0.013 | 1 mg/L EPA limit | |
| Copper 1991 to 2020 | 46 | 70% | 0% | 0.001 | 0.1 | 1.3 mg/L EPA limit | |
| Uranium 2016 to 2025 | 30 | 67% | 0% | 0.682 | 20 | 30 ug/L EPA limit | |
| Lead 1991 to 2006 | 24 | 13% | 0% | 0 | 2 | 15 ug/L EPA limit | |
| Sodium 1991 to 2025 | 112 | 100% | no limit | 2 | 29 | 20 mg/L health guideline | |
| Chloride 1991 to 2025 | 112 | 99% | no limit | 1.52 | 71.5 | 250 mg/L nuisance level | |
| Iron 1991 to 2025 | 79 | 16% | no limit | 0 | 440 | 300 ug/L nuisance level | |
| Manganese 1991 to 2025 | 75 | 19% | no limit | 0 | 14 | 300 ug/L health guideline | |
| Radon 1992 to 1995 | 12 | 100% | no limit | 740 | 2,670 | 2,000 pCi/L health guideline |
Get the free Teton County well report
One email with the numbers above, what they mean for a home in Teton County, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
The contaminants most often above their limit here are total coliform (9% of 32 samples) and e. coli (3% of 143 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride is widespread in local groundwater. It is mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Teton County
- Total coliform9% of 32 local samples were above the limit.
- E. coli3% of 143 local samples were above the limit.
- RadonMedian local reading is 740 pCi/L.
- NitrateRecommended for every private well, especially near farms or septic systems.
- ChlorideDetected in 99% of local samples.
- CopperDetected in 70% of local samples.
Treatment that fits the local profile
- Total coliform
- Inspect and repair the well cap and casing, then shock chlorinate and retest; UV disinfection whole-house; Chlorination system
- E. coli
- Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Chloride
- Point-of-use reverse osmosis; Distillation
Get your Teton County water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Teton County.
Common questions
Is there arsenic in well water in Teton County?
Arsenic was detected in 34% of 91 public well samples in Teton County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How high is radon in well water in Teton County?
The median radon level across 12 public samples in Teton County was 740 pCi/L, with a high of 2,670 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Teton County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Sources
- Idaho statewide ground water quality monitoring (IDWR EDMS): 872 samples in Teton County. Ground water quality results from the Idaho Department of Water Resources statewide monitoring program and partner agencies (ISDA, IDEQ, INL), EDMS bulk download. Retrieved September 9, 2026.
- USGS Water Quality Portal: 113 samples in Teton County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.