Well water in St. Joseph County, Indiana

Name: Private well water quality in St. Joseph County, Indiana
Creator: Well Water Nerd
License: Public domain (US federal government data)

1in8

Testing recommended

tested well samples in St. Joseph County exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal.

1,331 test results across 13 contaminants from at least 425 wells, 1934 to 2013; chloride has the most at 465. Data refreshed September 15, 2026.

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

An estimated 76,774 people in St. Joseph County get their drinking water from a private well, per USGS 2015 county water use. That is about 29% of residents.

Separately, the USGS national arsenic model estimates that 7% of the 76,774 people on private wells in St. Joseph County draw water above 10 ug/L (the model's range is 5% to 9%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside St. Joseph 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
Arsenic 1992 to 2013	12%	33	45%	0	20	10 ug/L EPA limit
Nitrate 1954 to 2013	6%	108	83%	0.548	18	10 mg/L EPA limit
Fluoride 1954 to 2013	0%	62	65%	0.1	0.7	4 mg/L EPA limit
Copper 1992 to 2013	0%	33	0%	0	0	1.3 mg/L EPA limit
Lead 1992 to 2013	0%	33	6%	0	10	15 ug/L EPA limit
Chloride 1934 to 2013	no limit	465	99%	12	240	250 mg/L nuisance level
Iron 1951 to 2013	no limit	457	89%	200	7,500	300 ug/L nuisance level
Sodium 1954 to 2013	no limit	73	100%	6.5	140	20 mg/L health guideline
Manganese 1954 to 2013	no limit	62	79%	64.6	780	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (2), E. coli (1), Uranium (1), Radon (1).

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 arsenic (12% of 33 samples) and nitrate (6% of 108 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, Iron, and Manganese 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 St. Joseph County

1
Arsenic
12% of 33 local samples were above the limit.
2
Nitrate
6% of 108 local samples were above the limit.
3
Coliform bacteria
Recommended for every private well, every year.
4
Radon
Median local reading is 143 pCi/L.
5
Chloride
Detected in 99% of local samples.
6
Iron
Detected in 89% of local samples.
7
Manganese
Detected in 79% of local samples.
8
Volatile organic compounds (VOCs)
255 leaking underground storage tank sites on record locally.

Test your St. Joseph County well for arsenic, nitrate and coliform bacteria

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 Indiana: certified labs, state programs and prices.

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

The rock under St. Joseph 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 Indiana

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.

Well Water Quality and Testing, Indiana Department of Health
Laboratories, IDEM

Contamination sources on record in St. Joseph County

IDEM records 255 leaking underground storage tank sites in St. Joseph County, among 299 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

255: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
44: other remediation projects

Treatment that fits the local profile

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Nitrate

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

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

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 arsenic

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For arsenic

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 iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in St. Joseph County

No water treatment company serves St. Joseph 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 St. Joseph County, and you get an email naming it first.

Common questions

Is there arsenic in well water in St. Joseph County?

Arsenic was detected in 45% of 33 public well samples in St. Joseph County, and 12% 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 often should I test a private well in St. Joseph 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 St. Joseph 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 Indiana dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 1,331 samples in St. Joseph 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.
USGS national arsenic model (Ayotte 2017): estimated share of 76,774 people on private wells in St. Joseph 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.
IDEM regulated sites: 299 regulated sites located in St. Joseph County. Leaking underground storage tank sites and state cleanup sites from the Indiana Department of Environmental Management. Retrieved September 16, 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.