Johnson County, Indiana
A shallow water table limits basements on 76% of Johnson County's mapped land, a higher share than 85% of US counties. Shrink-swell clay limits houses without basements on 1%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 40 flood losses here since 2016, 35% of them in buildings with basements. 35% of homes were built before 1980, against 50% nationally; the median home dates from 1993.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Johnson County
| Expansive clay (limits slab homes) | 1.1% |
| High water table (limits basements) | 75.6% |
| Septic fields very limited | 92.5% |
| Clay swell (LEP, by area) | 3.7% |
| High-swell land (LEP 6%+) | 0.0% |
| Urban land, not rated | 4.5% |
| Mapped soil | 206,215 acres |
How we count · survey areas IN081 (2025-09-03)
What the numbers mean here
On 76% of Johnson County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 47.90 in, 3.23 in above the 1991-2020 average year of 44.67 in.
USDA rates 93% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. No part of the county was in drought in the last 52 weeks.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
40 flood losses since 2016, $721,079 paid. The worst year was 2017, with 25. Foundations of the buildings, where recorded: 35% basements, 20% slabs, 25% crawl spaces, 20% elevated. Median water depth outside the building: 10 in.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 25 |
| 2018 | 2 |
| 2019 | 3 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 1 |
| 2025 | 5 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 44.67 in |
| 12 months to August 2026 | 47.90 in (+3.23) |
| 2025 | 45.49 in (+0.82) |
| Wettest year since 1895 | 2011: 55.72 in |
| Driest year since 1895 | 1934: 28.12 in |
| Days with 1 inch or more, normal at FRANKLIN WWTP (3 mi away) | 11.6 |
Homes
| Housing units | 65,915 |
| Median year built | 1993 |
| Built before 1980 | 35% |
| Built 2000 or later | 36% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $284,600 |
| Single-family detached | 77% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Shelby County, IN | 16 mi | 2% | 81% |
| Morgan County, IN | 19 mi | 5% | 59% |
| Marion County, IN | 20 mi | 4% | 52% |
| Brown County, IN | 22 mi | 1% | 21% |
| Bartholomew County, IN | 23 mi | 4% | 67% |
| Hancock County, IN | 28 mi | 4% | 96% |
| Hendricks County, IN | 29 mi | 14% | 84% |
| Monroe County, IN | 33 mi | 9% | 20% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status