Indiana well water by county: arsenic and nitrate
Modelled arsenic and nitrate for private-well users in every Indiana county, what to test for, and where to find a certified lab. Private wells aren’t covered by the Safe Drinking Water Act.
All 92 counties
- Elkhart CountyWell users 70,600Arsenic about 15 in 100Nitrate 1.4 mg/L
- Marion CountyWell users 65,900Arsenic about 10 in 100Nitrate 0.1 mg/L
- St. Joseph CountyWell users 61,200Arsenic about 18 in 100Nitrate 1.2 mg/L
- Allen CountyWell users 48,400Arsenic about 10 in 100Nitrate 0.0 mg/L
- Kosciusko CountyWell users 41,500Arsenic about 25 in 100Nitrate 0.5 mg/L
- Lake CountyWell users 40,400Arsenic about 13 in 100Nitrate 0.1 mg/L
- LaPorte CountyWell users 39,000Arsenic about 18 in 100Nitrate 1.4 mg/L
- Porter CountyWell users 37,600Arsenic about 20 in 100Nitrate 0.4 mg/L
- Madison CountyWell users 35,700Arsenic about 31 in 100Nitrate 0.0 mg/L
- Hendricks CountyWell users 33,500Arsenic about 9 in 100Nitrate 0.1 mg/L
- Delaware CountyWell users 32,600Arsenic about 20 in 100Nitrate 0.0 mg/L
- LaGrange CountyWell users 28,100Arsenic about 14 in 100Nitrate 1.6 mg/L
- Vigo CountyWell users 27,400Arsenic about 11 in 100Nitrate 1.0 mg/L
- Tippecanoe CountyWell users 26,700Arsenic about 14 in 100Nitrate 0.3 mg/L
- Hamilton CountyWell users 26,500Arsenic about 27 in 100Nitrate 0.0 mg/L
- Marshall CountyWell users 24,400Arsenic about 37 in 100Nitrate 0.7 mg/L
- Hancock CountyWell users 23,000Arsenic about 44 in 100Nitrate 0.0 mg/L
- Noble CountyWell users 22,900Arsenic about 17 in 100Nitrate 0.3 mg/L
- Grant CountyWell users 22,700Arsenic about 5 in 100Nitrate 0.0 mg/L
- Morgan CountyWell users 22,400Arsenic about 4 in 100Nitrate 0.3 mg/L
- Howard CountyWell users 22,000Arsenic about 36 in 100Nitrate 0.0 mg/L
- Shelby CountyWell users 21,900Arsenic about 27 in 100Nitrate 0.1 mg/L
- Henry CountyWell users 21,900Arsenic about 35 in 100Nitrate 0.1 mg/L
- Bartholomew CountyWell users 20,100Arsenic about 7 in 100Nitrate 0.5 mg/L
- Jasper CountyWell users 19,900Arsenic about 7 in 100Nitrate 0.1 mg/L
- Wayne CountyWell users 19,500Arsenic about 21 in 100Nitrate 0.3 mg/L
- Whitley CountyWell users 19,000Arsenic about 15 in 100Nitrate 0.0 mg/L
- Steuben CountyWell users 18,700Arsenic about 21 in 100Nitrate 0.3 mg/L
- Johnson CountyWell users 17,100Arsenic about 14 in 100Nitrate 0.2 mg/L
- Adams CountyWell users 16,600Arsenic about 11 in 100Nitrate 0.0 mg/L
- Boone CountyWell users 16,600Arsenic about 51 in 100Nitrate 0.0 mg/L
- DeKalb CountyWell users 16,400Arsenic about 14 in 100Nitrate 0.0 mg/L
- Starke CountyWell users 16,300Arsenic about 19 in 100Nitrate 0.3 mg/L
- Cass CountyWell users 15,900Arsenic about 25 in 100Nitrate 0.2 mg/L
- Miami CountyWell users 15,800Arsenic about 38 in 100Nitrate 0.1 mg/L
- Montgomery CountyWell users 14,800Arsenic about 24 in 100Nitrate 0.1 mg/L
- Huntington CountyWell users 14,000Arsenic about 14 in 100Nitrate 0.0 mg/L
- Wells CountyWell users 13,700Arsenic about 13 in 100Nitrate 0.0 mg/L
- White CountyWell users 13,200Arsenic about 20 in 100Nitrate 0.1 mg/L
- Carroll CountyWell users 12,900Arsenic about 28 in 100Nitrate 0.2 mg/L
- Wabash CountyWell users 12,600Arsenic about 30 in 100Nitrate 0.1 mg/L
- Jackson CountyWell users 12,400Arsenic about 6 in 100Nitrate 1.0 mg/L
- Clinton CountyWell users 12,300Arsenic about 51 in 100Nitrate 0.0 mg/L
- Putnam CountyWell users 12,100Arsenic about 6 in 100Nitrate 0.4 mg/L
- Owen CountyWell users 12,000Arsenic about 2 in 100Nitrate 0.4 mg/L
- Posey CountyWell users 11,900Arsenic about 11 in 100Nitrate 0.4 mg/L
- Fulton CountyWell users 11,700Arsenic about 22 in 100Nitrate 0.3 mg/L
- Randolph CountyWell users 11,600Arsenic about 53 in 100Nitrate 0.0 mg/L
- Vanderburgh CountyWell users 11,200Arsenic about 11 in 100Nitrate 0.4 mg/L
- Decatur CountyWell users 10,900Arsenic about 11 in 100Nitrate 0.2 mg/L
- Jay CountyWell users 10,800Arsenic about 11 in 100Nitrate 0.0 mg/L
- Daviess CountyWell users 10,100Arsenic about 12 in 100Nitrate 0.4 mg/L
- Rush CountyWell users 9,100Arsenic about 24 in 100Nitrate 0.1 mg/L
- Clay CountyWell users 8,600Arsenic about 9 in 100Nitrate 0.2 mg/L
- Pulaski CountyWell users 8,600Arsenic about 23 in 100Nitrate 0.0 mg/L
- Tipton CountyWell users 8,300Arsenic about 31 in 100Nitrate 0.0 mg/L
- Franklin CountyWell users 8,200Arsenic about 3 in 100Nitrate 1.0 mg/L
- Parke CountyWell users 8,100Arsenic about 13 in 100Nitrate 0.3 mg/L
- Fountain CountyWell users 7,700Arsenic about 15 in 100Nitrate 0.2 mg/L
- Newton CountyWell users 7,700Arsenic about 6 in 100Nitrate 0.1 mg/L
- Orange CountyWell users 7,400Arsenic about 1 in 100Nitrate 1.0 mg/L
- Washington CountyWell users 7,000Arsenic about 2 in 100Nitrate 1.6 mg/L
- Fayette CountyWell users 6,900Arsenic about 10 in 100Nitrate 2.8 mg/L
- Monroe CountyWell users 6,800Arsenic about 1 in 100Nitrate 0.9 mg/L
- Ripley CountyWell users 6,400Arsenic about 7 in 100Nitrate 0.6 mg/L
- Knox CountyWell users 6,400Arsenic about 5 in 100Nitrate 0.9 mg/L
- Jennings CountyWell users 6,200Arsenic about 5 in 100Nitrate 0.1 mg/L
- Greene CountyWell users 5,500Arsenic about 5 in 100Nitrate 0.3 mg/L
- Gibson CountyWell users 5,400Arsenic about 18 in 100Nitrate 0.7 mg/L
- Warren CountyWell users 5,200Arsenic about 17 in 100Nitrate 0.0 mg/L
- Lawrence CountyWell users 5,000Arsenic about 2 in 100Nitrate 1.1 mg/L
- Spencer CountyWell users 4,800Arsenic about 2 in 100Nitrate 0.5 mg/L
- Blackford CountyWell users 4,400Arsenic about 6 in 100Nitrate 0.0 mg/L
- Harrison CountyWell users 4,100Arsenic about 1 in 100Nitrate 1.3 mg/L
- Sullivan CountyWell users 4,000Arsenic about 8 in 100Nitrate 0.4 mg/L
- Union CountyWell users 3,400Arsenic about 5 in 100Nitrate 1.4 mg/L
- Vermillion CountyWell users 3,100Arsenic about 20 in 100Nitrate 0.4 mg/L
- Benton CountyWell users 3,100Arsenic about 12 in 100Nitrate 0.0 mg/L
- Warrick CountyWell users 3,000Arsenic about 10 in 100Nitrate 0.4 mg/L
- Dubois CountyWell users 2,800Arsenic about 8 in 100Nitrate 0.7 mg/L
- Clark CountyWell users 2,700Arsenic about 5 in 100Nitrate 1.0 mg/L
- Perry CountyWell users 2,700Arsenic about 3 in 100Nitrate 0.2 mg/L
- Dearborn CountyWell users 2,700Arsenic about 2 in 100Nitrate 0.8 mg/L
- Brown CountyWell users 2,400Arsenic about 2 in 100Nitrate 0.2 mg/L
- Martin CountyWell users 2,000Arsenic about 3 in 100Nitrate 0.3 mg/L
- Jefferson CountyWell users 1,900Arsenic about 5 in 100Nitrate 0.5 mg/L
- Scott CountyWell users 1,800Arsenic about 5 in 100Nitrate 0.4 mg/L
- Crawford CountyWell users 1,800Arsenic about 2 in 100Nitrate 0.2 mg/L
- Pike CountyWell users 1,700Arsenic about 6 in 100Nitrate 0.3 mg/L
- Switzerland CountyWell users 1,100Arsenic about 5 in 100Nitrate 0.6 mg/L
- Floyd CountyWell users 720Arsenic about 2 in 100Nitrate 0.6 mg/L
- Ohio CountyWell users 220Arsenic about 5 in 100Nitrate 0.7 mg/L
Each mark = 1 in 100 well users the model places above 10 µg/L arsenic (scale 0–10)10 mg/L nitrate: the federal limit (MCL) for public systems
- These figures describe the area, not your well. Only a lab test shows what’s in your water.
- CDC says the Well Water Index figures “do not describe risk to individual wells.” (CDC Tracking Network)
- The arsenic model is better at spotting low-arsenic areas than at confirming high ones.
- Well-user counts are 2010 USGS estimates; tract values are averages over each census tract.
- Total coliform bacteriaEvery year
- NitrateEvery year
- Total dissolved solidsEvery year
- pHEvery year
- ArsenicAsk your local health department
EPA: Private Drinking Water Wells · CDC: Guidelines for Testing Well Water
Use a state-certified lab
Indiana Department of Health Laboratories lists the laboratories certified to test drinking water in Indiana.
Screening tells you if something is worth a closer look
A lab result is the number you can act on.
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Lab-certified results
ETR Labs Basic Water Quality Test Kit
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
- Analyzed by Environmental Testing and Research Laboratories (ETR Labs), Leominster, MA · ISO/IEC 17025:2017, ANAB certificate AT-2638
- Turnaround: 2–4 business days after the lab receives it
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
Screening: quick check, not lab-grade
Watersafe Drinking Water Test Kit
Silver Lake Research
Lead, bacteria, nitrate, copper, iron, chlorine, hardness and pH
- Turnaround: Minutes; the bacteria test can take up to 48 hours
What it can't tell you: Each test gives a yes/no or a rough range, not a lab number, and it cannot detect PFAS or arsenic.
A mail-in kit’s lab is accredited (ISO/IEC 17025) but may not be certified by your state. For a home sale, a loan, or a health-department follow-up, use a state-certified lab.
Indiana well water
Sources: CDC Well Water Index (2024) · USGS arsenic and nitrate models · USGS domestic well populations · EPA and CDC testing guidance. Data last updated 2026-10-08. All sources →
How many people use private wells in Indiana?
About 1.4 million people across 92 Indiana counties, by the USGS 2010 estimate. USGS models place about 247,900 of them in areas where wells are likely to be above the 10 µg/L arsenic limit. These are area estimates, not well results.
Are private wells regulated in Indiana?
The quality and safety of drinking water from private domestic wells are not regulated by the Federal Government under the Safe Drinking Water Act nor by most state governments and laws. (EPA) Testing and treatment are the owner's responsibility.
Where can I get my well tested in Indiana?
Indiana Department of Health Laboratories keeps the list of laboratories certified to test drinking water in Indiana. Only use laboratories that are certified to do drinking water testing. (EPA)