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Buying land in Twin Falls County, Idaho: what to check

Twin Falls County covers 1,922 square miles of land and 7 of water in Idaho, with about 96,509 residents in 2024 (up 7.2% since 2020). The 2020 Census counted 99% of its land as rural and 65% of residents as living in urban areas. Farms operate 37% of the county's land. Below: how much of Twin Falls County floods, what its soils allow, what farmland is worth and how often it's in drought, from free public data with every source linked.

Check a location in Twin Falls CountySee a sample report

Twin Falls County at a glance

In the 100-year floodplain

1.7%

Above the state's county median (1.3%)

FEMA National Risk Index

Hydric (wetland-type) soils

under 1%

Below the state's county median (1.6%)

USDA NRCS Web Soil Survey (SSURGO)

Soils very limited for septic

92%

USDA NRCS Web Soil Survey (SSURGO)

Farm land value, 2022

$6,129/acre

Above the state's county median ($3,845)

USDA NASS, 2022 Census of Agriculture

Weeks in severe drought

45%

Share of weekly maps, 2021–2026

U.S. Drought Monitor county statistics

Land classed rural

99%

Census 2020 Census urban and rural classification

What to check before buying land in Twin Falls County

Ordered by what Twin Falls County's numbers point to. Every parcel differs, so treat this as where to look first.

  1. 1.Budget for a perc test and maybe an engineered septic

    USDA rates 92% of Twin Falls County's mapped soils "very limited" for conventional septic absorption fields and under 1% "not limited".

    Without city sewer you need a septic permit from the county or state health department. Make the offer contingent on a passing soil or perc test; mound and aerobic systems can cost several times a conventional one.

    Guide: Perc tests and septic systems

  2. 2.Prove the water supply before you buy

    At least half of Twin Falls County was in severe drought (D2) or worse in 45% of the 262 weekly U.S. Drought Monitor maps from 2021 to 2026. Idaho allocates water by permit or water right, so a well or pond isn't automatic.

    Ask whether the land has a public water connection, an existing well (and its log and yield), or neighbors' well depths from the state well database. For a new well, check permits and typical depth with the state agency first.

    Guide: Wells, public water and water rights

  3. 3.Confirm legal road access and power

    The 2020 Census classified 99% of Twin Falls County's land area as rural.

    Rural tracts are often sold without recorded access or a power line nearby. Get the title company to confirm a recorded easement or public road frontage, and ask the electric co-op what a line extension costs.

    Guide: Road access and landlocked land

  4. 4.Check wildfire exposure and insurance

    FEMA rates Twin Falls County's wildfire risk relatively moderate, and 4.8% of the county's area is in the wildfire exposure zone the National Risk Index uses.

    Ask an insurer for a quote early; some carriers won't write new policies in high-hazard areas. Check access for fire trucks, nearby fire stations and the vegetation around the building site.

    Guide: Wildfire risk for rural land

  5. 5.Check slope at the building site

    18% of Twin Falls County's mapped soils have an average slope over 15% (USDA SSURGO).

    Steep ground means grading, retaining walls, longer driveways and erosion control. Compare the slope at the house site and along the access route, not just the parcel average.

    Guide: Terrain and slope

  6. 6.Confirm the flood zone at your exact spot

    1.7% of the county's area is in the 1%-annual-chance (100-year) floodplain FEMA's National Risk Index uses for inland flooding; under 1% of its mapped soils flood occasionally or frequently.

    Even where little of the county floods, creeks and low spots do. Check the FEMA zone at the building site and the driveway route.

    Guide: Flood zones before buying land

Flood zones, wetlands and water in Twin Falls County

Area in the 1%-annual-chance (100-year) floodplain
1.7%, 19th highest of 44 in Idaho FEMA National Risk Index
Mapped soils that flood occasionally or frequently
under 1% USDA NRCS Web Soil Survey (SSURGO)
Hydric soils (a federal wetland indicator)
under 1% USDA NRCS Web Soil Survey (SSURGO)
Poorly or very poorly drained soils
under 1% USDA NRCS Web Soil Survey (SSURGO)
Surface water (lakes, rivers, reservoirs)
7 sq mi Census 2024 Gazetteer Files
Drought on 2026-10-27
100% moderate or worse, 100% severe or worse U.S. Drought Monitor county statistics

The floodplain share is the area FEMA's National Risk Index counts as exposed to inland flooding, mostly mapped 100-year flood zones. It says how common flood-prone land is in Twin Falls County, not whether a given parcel floods. For that, look up the zone at your exact point on the FEMA Flood Map Service Center or run the free check.

Soils and terrain

Prime farmland
0% USDA NRCS Web Soil Survey (SSURGO)
Prime only if drained, irrigated or protected
36% USDA NRCS Web Soil Survey (SSURGO)
Farmland of statewide importance
25% USDA NRCS Web Soil Survey (SSURGO)
Average slope over 15%
18% USDA NRCS Web Soil Survey (SSURGO)
Very limited for septic absorption fields
92% USDA NRCS Web Soil Survey (SSURGO)
Not limited for septic absorption fields
under 1% USDA NRCS Web Soil Survey (SSURGO)

Shares of Twin Falls County's soil-surveyed land (about 1,249,357 acres, open water excluded), using each map unit's dominant condition in USDA's SSURGO soil survey. Soils change within a few hundred feet, so the soil at your building site is what matters.

Farms and land use

Farms (2022)
1,169 USDA NASS, 2022 Census of Agriculture
Share of the county's land in farms
37% USDA NASS, 2022 Census of Agriculture
Average farm size
393 acres (median 34) USDA NASS, 2022 Census of Agriculture
Average value of land and buildings
$6,129 per acre, 9th highest of 44 in Idaho USDA NASS, 2022 Census of Agriculture
Cropland
249,600 acres USDA NASS, 2022 Census of Agriculture
Pasture and rangeland
196,917 acres USDA NASS, 2022 Census of Agriculture
Woodland on farms
146 acres USDA NASS, 2022 Census of Agriculture
Irrigated land
236,196 acres USDA NASS, 2022 Census of Agriculture

Natural hazard ratings

FEMA's National Risk Index rates each hazard for Twin Falls County relative to every other U.S. county. Overall risk: Relatively Low.

  • Winter weatherRelatively High
  • Heat waveRelatively Moderate
  • LandslideRelatively Moderate
  • WildfireRelatively Moderate
  • EarthquakeRelatively Low
  • River and inland floodingRelatively Low
  • LightningRelatively Low
  • Strong windRelatively Low
  • DroughtVery Low
  • HailVery Low
  • TornadoVery Low

FEMA National Risk Index, December 2025

Questions about buying land in Twin Falls County

How much of Twin Falls County, ID is in a flood zone?

About 1.7% of Twin Falls County's area is in the 1%-annual-chance (100-year) floodplain used by FEMA's National Risk Index (December 2025), 19th highest of 44 counties in Idaho. Whether a given parcel is in a flood zone depends on its exact location, so check the FEMA map at your pin.

How much does land cost per acre in Twin Falls County?

The 2022 Census of Agriculture put the average value of farm land and buildings in Twin Falls County at $6,129 an acre, 9th highest of 44 counties in Idaho (the median Idaho county was $3,845). It's a self-reported average across farms, so small homesites and recreational tracts often sell for more per acre.

Will a septic system work on land in Twin Falls County?

Often, but test first. USDA soil surveys rate 92% of Twin Falls County's mapped soils very limited for conventional septic absorption fields, usually because of wetness, slow permeability, shallow rock or flooding. A perc or soil test on the parcel decides what system the health department will permit.

Is there good farmland in Twin Falls County?

0% of Twin Falls County's mapped soils are prime farmland, 36% are prime only if drained, irrigated or protected from flooding, and 25% are farmland of statewide importance (USDA SSURGO). The 2022 Census of Agriculture counted 1,169 farms averaging 393 acres.

How often is Twin Falls County in drought?

Since 2021, at least half of the county was in severe drought or worse in 45% of weekly U.S. Drought Monitor maps, and in extreme drought in 12%. On 2026-10-27, 100% of the county was in moderate drought or worse.

Can I check a specific property in Twin Falls County?

Yes. Enter the address or drop a pin anywhere in Twin Falls County on the free check. It shows which checks return data at that exact point, and the full report costs $29: flood zone, slope, soils, wetlands, roads, power lines, wildfire and more, each with its source. It is a screen of public maps, not a survey, title search or perc test.

Check the parcel, not just the county

County numbers tell you what to look for. The free check looks at your exact point in Twin Falls County: flood zone, slope, soils, wetlands, roads, power and more. The full report is $29.

Check a location in Twin Falls County

What these numbers can't tell you

  • County shares describe Twin Falls County as a whole; a parcel can be entirely in or out of a flood zone, wetland or poor soil.
  • It doesn't look at the whole parcel, its boundaries, title, easements, zoning or permits.
  • It isn't a survey, appraisal, elevation certificate, soil or perc test, or Phase I environmental site assessment.
  • It can't see local distribution power lines, driveways, legal access, wells or mineral rights.
  • Maps lag behind the ground, and distances are straight-line, not driving distance.

Sources and vintages

Summarized per county by our build script on 2026-10-31. County figures cover the whole county; checks on the report are at your point.