Quick answer
About 1,405,000 people in Indiana (21.7% of residents) got their water from private wells in 2010, according to USGS estimates. Indiana Department of Health runs the state’s private well guidance. IDEM's Statewide Groundwater Monitoring Network tests the private wells of randomly selected qualifying applicants free of charge (a detailed well log is required); it is a periodic sampling study, not an on-demand service.
- People on private wells
- 1,405,192
- Share of residents
- 21.7%
- Rank among states
- 10th
- Well users modeled above 10 µg/L arsenic
- 17.7%
Where to get your well tested in Indiana
- Indiana Department of Health: Water Supply Program, the state’s guidance for private well owners.
- Well water testing in Indiana: what to test for and how to collect a sample.
- Certified laboratories in Indiana. Use a lab certified for drinking water, so results are reliable.
Free or low-cost testing
IDEM's Statewide Groundwater Monitoring Network tests the private wells of randomly selected qualifying applicants free of charge (a detailed well log is required); it is a periodic sampling study, not an on-demand service. (source)
Mail-in lab kits are another option when no local lab is convenient. See well water test kits for what home kits can and can’t tell you.
What to test for
- Every year: total coliform bacteria and nitrate.
- Before buying equipment: pH, hardness, iron, manganese and, if there’s a smell, hydrogen sulfide.
- Based on location: arsenic, uranium and radon, PFAS, and lead in older plumbing.
USGS modeling estimates that about 17.7% of Indiana’s private well users have water above the 10 µg/L arsenic limit. Arsenic has no taste or smell, so include it in your first test.
Private wells by county
Estimated people relying on private wells in each Indiana county in 2010, the share of residents that represents, and the modeled share of well users with arsenic above 10 µg/L. These are USGS model estimates (2010 population), not measurements of any well. Arsenic is hidden for counties with fewer than 500 well users.
| County | People on wells | Share | Arsenic >10 µg/L |
|---|---|---|---|
| Elkhart County | 70,634 | 35.8% | 15.1% |
| Marion County | 65,920 | 7.3% | 9.8% |
| St. Joseph County | 61,195 | 22.9% | 17.9% |
| Allen County | 48,354 | 13.6% | 9.8% |
| Kosciusko County | 41,544 | 53.7% | 25.0% |
| Lake County | 40,447 | 8.2% | 13.0% |
| LaPorte County | 39,031 | 35.0% | 18.5% |
| Porter County | 37,555 | 22.9% | 19.8% |
| Madison County | 35,665 | 27.1% | 31.1% |
| Hendricks County | 33,455 | 23.0% | 9.4% |
| Delaware County | 32,551 | 27.7% | 19.9% |
| LaGrange County | 28,094 | 75.7% | 14.2% |
Show all 92 counties
| Vigo County | 27,394 | 25.4% | 11.4% |
| Tippecanoe County | 26,659 | 15.4% | 14.6% |
| Hamilton County | 26,457 | 9.6% | 27.4% |
| Marshall County | 24,404 | 51.9% | 37.0% |
| Hancock County | 23,006 | 32.9% | 43.7% |
| Noble County | 22,920 | 48.2% | 16.7% |
| Grant County | 22,729 | 32.4% | 5.1% |
| Morgan County | 22,368 | 32.5% | 4.2% |
| Howard County | 22,012 | 26.6% | 36.2% |
| Shelby County | 21,917 | 49.3% | 26.5% |
| Henry County | 21,880 | 44.2% | 34.7% |
| Bartholomew County | 20,070 | 26.1% | 6.9% |
| Jasper County | 19,922 | 59.5% | 6.8% |
| Wayne County | 19,517 | 28.3% | 20.5% |
| Whitley County | 19,006 | 57.1% | 14.7% |
| Steuben County | 18,698 | 54.7% | 20.9% |
| Johnson County | 17,089 | 12.2% | 14.6% |
| Adams County | 16,603 | 48.3% | 10.9% |
| Boone County | 16,560 | 29.2% | 51.6% |
| DeKalb County | 16,440 | 38.9% | 13.6% |
| Starke County | 16,320 | 69.9% | 19.4% |
| Cass County | 15,943 | 40.9% | 25.2% |
| Miami County | 15,804 | 42.8% | 38.0% |
| Montgomery County | 14,769 | 38.7% | 24.4% |
| Huntington County | 13,978 | 37.7% | 13.6% |
| Wells County | 13,683 | 49.5% | 12.8% |
| White County | 13,178 | 53.5% | 19.5% |
| Carroll County | 12,867 | 63.8% | 28.5% |
| Wabash County | 12,625 | 38.4% | 29.7% |
| Jackson County | 12,435 | 29.3% | 6.1% |
| Clinton County | 12,259 | 36.9% | 50.3% |
| Putnam County | 12,110 | 31.9% | 5.6% |
| Owen County | 11,974 | 55.5% | 2.0% |
| Posey County | 11,925 | 46.0% | 10.8% |
| Fulton County | 11,695 | 56.1% | 22.1% |
| Randolph County | 11,618 | 44.4% | 52.8% |
| Vanderburgh County | 11,153 | 6.2% | 11.2% |
| Decatur County | 10,895 | 42.3% | 11.3% |
| Jay County | 10,829 | 51.0% | 11.2% |
| Daviess County | 10,144 | 32.1% | 12.3% |
| Rush County | 9,105 | 52.4% | 23.5% |
| Clay County | 8,575 | 31.9% | 8.8% |
| Pulaski County | 8,558 | 63.9% | 23.0% |
| Tipton County | 8,279 | 52.0% | 30.7% |
| Franklin County | 8,249 | 35.7% | 3.0% |
| Parke County | 8,083 | 46.6% | 13.4% |
| Fountain County | 7,743 | 44.9% | 14.9% |
| Newton County | 7,719 | 54.2% | 5.9% |
| Orange County | 7,429 | 37.4% | 1.2% |
| Washington County | 6,974 | 24.7% | 2.0% |
| Fayette County | 6,891 | 28.4% | 10.4% |
| Monroe County | 6,778 | 4.9% | 1.2% |
| Ripley County | 6,437 | 22.3% | 7.1% |
| Knox County | 6,417 | 16.7% | 4.8% |
| Jennings County | 6,176 | 21.7% | 5.5% |
| Greene County | 5,517 | 16.6% | 4.7% |
| Gibson County | 5,384 | 16.1% | 17.8% |
| Warren County | 5,208 | 61.2% | 17.5% |
| Lawrence County | 4,993 | 10.8% | 1.6% |
| Spencer County | 4,848 | 23.1% | 2.5% |
| Blackford County | 4,392 | 34.4% | 6.0% |
| Harrison County | 4,105 | 10.4% | 1.3% |
| Sullivan County | 4,006 | 18.7% | 8.0% |
| Union County | 3,434 | 45.7% | 5.0% |
| Vermillion County | 3,054 | 18.8% | 19.4% |
| Benton County | 3,050 | 34.4% | 12.2% |
| Warrick County | 3,023 | 5.1% | 9.7% |
| Dubois County | 2,836 | 6.8% | 8.4% |
| Clark County | 2,691 | 2.4% | 4.6% |
| Perry County | 2,687 | 13.9% | 2.4% |
| Dearborn County | 2,653 | 5.3% | 2.3% |
| Brown County | 2,422 | 15.9% | 2.0% |
| Martin County | 1,960 | 19.0% | 3.1% |
| Jefferson County | 1,945 | 6.0% | 4.7% |
| Scott County | 1,759 | 7.3% | 4.6% |
| Crawford County | 1,754 | 16.4% | 1.6% |
| Pike County | 1,681 | 13.1% | 6.0% |
| Switzerland County | 1,143 | 10.8% | 5.3% |
| Floyd County | 717 | 1.0% | 1.5% |
| Ohio County | 217 | 3.5% | – |
Counties with the highest modeled arsenic share: Randolph County (52.8%), Boone County (51.6%), Clinton County (50.3%), Hancock County (43.7%), Miami County (38.0%).
After you get results
Enter your numbers in the test results tool to see what needs treating and in what order. The guide to reading a well water test explains units and limits.
Common questions
Does Indiana offer free well water testing?
IDEM's Statewide Groundwater Monitoring Network tests the private wells of randomly selected qualifying applicants free of charge (a detailed well log is required); it is a periodic sampling study, not an on-demand service.
Who oversees private wells in Indiana?
Indiana Department of Health (Water Supply Program) publishes guidance for private well owners. Private wells aren’t covered by the federal Safe Drinking Water Act, so testing and treatment are up to the owner.
How many people use private wells in Indiana?
USGS estimates about 1,405,000 people, or 21.7% of the population in 2010. That ranks 10th of the states covered by the estimate.
What should I test my well for in Indiana?
Test every year for total coliform bacteria and nitrate, plus pH, hardness, iron and manganese before buying equipment. Arsenic is a known concern in parts of Indiana, so add it to the first test.
Sources
- Indiana Department of Health: Water Supply Program
- Indiana Department of Health: well water testing
- Indiana certified laboratories
- Indiana free or low-cost testing
- USGS data release: domestic well locations and populations served, 2000 and 2010 (Johnson, Belitz and Lombard, 2019)
- CDC Environmental Public Health Tracking: private well water data (from USGS)