Well water in Butte County, Idaho

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Testing recommended

tested well samples in Butte County exceeded the EPA limit for E. coli (0 MPN/100mL), based on public data from USGS Water Quality Portal and Idaho statewide ground water quality monitoring (IDWR EDMS).

45,958 test results across 15 contaminants from at least 416 wells, 1949 to 2026; chloride has the most at 12,559. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 1,087 people in Butte County get their drinking water from a private well, per USGS 2015 county water use. That is about 43% of residents.

Separately, the USGS national arsenic model estimates that 4% of the 1,087 people on private wells in Butte County draw water above 10 ug/L (the model's range is 3% to 5%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Butte 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	Above limit	Samples	Detected	Median	Highest	Limit
E. coli 1991 to 2011	5%	38	5%	0	190	0 MPN/100mL EPA limit
Nitrate 1949 to 2026	5%	12,282	99%	1.5	585	10 mg/L EPA limit
Radium (226 + 228) 1989 to 1992	1%	163	44%	0	21	5 pCi/L EPA limit
Lead 1962 to 2026	<1%	2,123	34%	0	130	15 ug/L EPA limit
Fluoride 1949 to 2026	<1%	1,542	94%	0.2	98	4 mg/L EPA limit
Arsenic 1950 to 2026	<1%	1,859	84%	1.9	19	10 ug/L EPA limit
Uranium 1957 to 2026	<1%	458	99%	1.78	81,600	30 ug/L EPA limit
Copper 1962 to 2026	<1%	1,586	46%	0	12.9	1.3 mg/L EPA limit
Nitrite 1991 to 2010	0%	40	8%	0	0.01	1 mg/L EPA limit
Chloride 1949 to 2026	no limit	12,559	100%	18.7	1,500	250 mg/L nuisance level
Sodium 1949 to 2026	no limit	9,318	100%	11.7	1,300	20 mg/L health guideline
Manganese 1950 to 2026	no limit	1,973	56%	0	38,700	300 ug/L health guideline
Iron 1949 to 2026	no limit	1,957	77%	40	851,000	300 ug/L nuisance level
Radon 1989 to 1995	no limit	59	100%	170	1,200	2,000 pCi/L health guideline

Sampled fewer than 10 times, too few to summarize: Total coliform (1).

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	7%4,421 samples	4%2,990 samples	3%3,050 samples	5%1,821 samples
Lead	2%927 samples	<1%507 samples	<1%401 samples	<1%288 samples
Arsenic	0%585 samples	<1%554 samples	<1%426 samples	<1%294 samples
Copper	0%417 samples	0%486 samples	<1%405 samples	0%278 samples
Fluoride	<1%1,158 samples	0%222 samples	<1%119 samples	0%43 samples
Uranium	0%88 samples	<1%180 samples	0%128 samples	0%62 samples

Nitrate, lead, arsenic, copper, fluoride, uranium have held within a few points between the two most recent periods with enough samples.

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are e. coli (5% of 38 samples), nitrate (5% of 12,282 samples), and radium (226 + 228) (1% of 163 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, Manganese, and Iron are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Butte County

1
E. coli
5% of 38 local samples were above the limit.
2
Nitrate
5% of 12,282 local samples were above the limit.
3
Radium (226 + 228)
1% of 163 local samples were above the limit.
4
Lead
<1% of 2,123 local samples were above the limit.
5
Fluoride
<1% of 1,542 local samples were above the limit.
6
Arsenic
<1% of 1,859 local samples were above the limit.
7
Uranium
<1% of 458 local samples were above the limit.

Test your Butte County well for E. coli, nitrate and radium (226 + 228)

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Idaho: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Butte County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Butte County

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Idaho

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Wells, Idaho DEQ
Drinking Water Testing and Certification, Idaho Department of Health and Welfare

Treatment that fits the local profile

E. coli

Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

Radium (226 + 228)

Water softener (cation exchange); Point-of-use reverse osmosis

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

Fluoride

Point-of-use reverse osmosis; Activated alumina; Distillation

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For E. coli

UV disinfection system

whole-house, at the point of entry, about $900

Fix the well cap and casing first; UV keeps bacteria from returning.

For E. coli

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

For nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For nitrate

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For lead

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

Free, no obligation

Get on the list for a free in-home water test in Butte County

No water treatment company serves Butte County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Butte County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Butte County?

Arsenic was detected in 84% of 1,859 public well samples in Butte County, and <1% 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 Butte County?

The median radon level across 59 public samples in Butte County was 170 pCi/L, with a high of 1,200 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Butte 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.

Counties near Butte County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the Idaho dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 45,451 samples in Butte 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.
Idaho statewide ground water quality monitoring (IDWR EDMS): 507 samples in Butte 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 national arsenic model (Ayotte 2017): estimated share of 1,087 people on private wells in Butte County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 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.