Bolthole Index

Twin Falls County, Idaho

Building permits, zoning and septic rules in Twin Falls County, Idaho

50Index Score / 100
#33 of 44 in Idaho

Unincorporated Twin Falls County, Idaho requires building permits for covered construction and even interior remodeling, with only limited exemptions12. County zoning applies on unincorporated land, while the Buhl, Filer, Hansen, Hollister, Kimberly, Murtaugh and Twin Falls areas of impact can follow different zoning rules34. Septic permits come from the South Central Public Health District, not the county5.

At a glance

Building permit
Required for most work; a residential accessory building under 200 sq ft is exempt1
Zoning
Yes - county zoning covers unincorporated land, with districts and overlays shown on official zoning maps36
Septic
South Central Public Health District issues subsurface sewage disposal permits, not the county5
RV living
An occupied RV may stay on a lot no more than 90 days in a calendar year7
Manufactured/mobile homes
Allowed as single-family dwellings in the zones listed in county code, with Building Department approval; minimum 12-foot width and 1,000 sq ft89
Owner-builder exemption
An owner working on their own Idaho land may be exempt from contractor registration, but permits and inspections still apply1011
Minimum RR-zone lot size
1 acre with individual water and septic, or 9,000 sq ft with public or private sewer and water12
Wells
A drilling permit from Idaho Dept. of Water Resources is required for wells more than 18 feet deep, statewide13

Who to call

Building permits

Twin Falls County Building Department

Building permit issuance, plan review and construction/mechanical inspections

(208) 933-9279

630 Addison Ave. West, Ste 1101, Twin Falls, ID 83301

Zoning

Twin Falls County Planning & Zoning Department

Zoning permits, conditional-use and public-hearing applications, and answering what a parcel is zoned

208-734-9490

630 Addison Ave. West, Suite 1100, Twin Falls, Idaho 83301

Zoning

Twin Falls County Zoning Code (Title 8)

Codifies zoning districts, lot/setback requirements, and rules for RVs and manufactured homes in unincorporated Twin Falls County

Septic permits

South Central Public Health District - Twin Falls Main Office

Subsurface sewage disposal (septic) permits and land-development/septic records for Twin Falls County

(208) 737-5900

septic@phd5.id.gov

1020 Washington Street North, Twin Falls, ID 83301

Septic permits

South Central Public Health District - Septic Records Portal

Online lookup of existing septic and land-development records, including for Twin Falls County

(208) 737-5916

Online permits →

Contact details are copied from each office’s official page and were checked against it on October 12, 2026.

Off-grid gear

Going off-grid in Twin Falls County means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Twin Falls County, Idaho?

Unincorporated Twin Falls County requires a building permit when a structure is erected, constructed, remodeled, enlarged, altered, repaired, moved, removed, converted or demolished1. The county specifically requires permits for interior remodeling, including nonstructural-wall work and changes to window or door sizes, and directs applicants to ask the Building Department about limited exemptions2. A residential accessory building under 200 square feet can qualify for an exemption1. Twin Falls County has adopted the 2018 building, residential, energy, mechanical, fuel-gas, existing-building and fire codes with Idaho amendments, plus the 2018 Idaho Manufactured Home Installation Standards14. Electrical, plumbing and HVAC work requires separate permits15. State plumbing, electrical, gas, mechanical, fireplace, and firewall or sprinkler rough-ins must be signed off before the county framing inspection; corresponding finals must precede the county final building inspection16. A final inspection and an occupancy permit are required before a new or remodeled structure is used, and occupancy approval may be withheld while a required inspection is incomplete17.

Inside Twin Falls, Kimberly, Buhl and Hansen city limits, the city handles building permits18192021. South Central Public Health District remains the district administering state septic rules in Twin Falls County; Hansen also requires a city private-sewage permit and inspection222324.

Who is the Twin Falls County Building Department and how do you reach them?

The Twin Falls County Building Department reviews plans, issues building permits and handles building and mechanical inspections25. Reach the department at 630 Addison Ave. West, Ste 1101, Twin Falls, ID 83301, or (208) 933-9279; request building inspections at (208) 735-4429 and mechanical inspections at (208) 735-443225. Complete residential submissions are reviewed in the order received, with plan review usually estimated at no more than 7 business days26. A permit expires 180 days after issuance or the last inspection, so keep inspections current26. Give the permit number, property address, contact name and phone number, and inspection type when requesting an inspection; requests after 7:00 a.m. move to the next working day16. The county links a Building & Zoning Fee Schedule from its Community Development Services page, and the cited schedule is the 2025 edition, so confirm the current fee with the Building Department27. For parcel zoning and land-use applications, contact the Planning & Zoning Department at 630 Addison Ave. West, Suite 1100, Twin Falls, Idaho 83301, or 208-734-949028.

Does Twin Falls County have zoning?

Twin Falls County zoning covers unincorporated land, including areas of city impact where city regulations may be adopted by reference3. Inside city limits, Twin Falls, Kimberly, Buhl, Filer, Hansen and Hollister set their own zoning293031323334. South Central Public Health District administers state septic rules for Twin Falls County, while Hansen additionally requires city approval of private sewage systems222324.

For unincorporated parcels, ask Planning & Zoning to identify the controlling county or area-of-impact code and mapped district4628. Rural Residential lots generally need 1 acre with individual water and sewage, or 9,000 square feet with public or private sewer and water12. RR front and rear yards are generally 30 feet and interior side yards 7 feet, with larger yards for taller buildings35. Canyon Rim Overlay parcels have separate setback and height controls3536. We could not confirm a general minimum size for site-built homes; ask Planning & Zoning about the parcel's district28.

How do septic permits work in Twin Falls County?

Septic permits in Twin Falls County are not issued by the county: the South Central Public Health District administers Idaho's statewide subsurface sewage disposal rules for the county523. The county zoning code itself bars anyone from installing or using a sewage-disposal facility until the district approves it, and where a district-approved public sewer is reasonably available the lot must connect to it37. Reach the district's Twin Falls main office at 1020 Washington Street North, Twin Falls, ID 83301, phone (208) 737-5900, or email septic questions to septic@phd5.id.gov22. Use the district’s septic records portal to look up existing systems; septic permits were not required before 1971, so older systems may lack records3839. South Central Public Health District inspects individual septic installations; when inspection preparation is required, give at least 48 hours’ advance notice, excluding weekends and holidays40. About 8% of Twin Falls County soils are rated ‘not limited’ for conventional septic drain fields; that does not rule out septic elsewhere, but makes a site evaluation essential and an engineered system possible41.

Can you live in an RV or tiny home on your land in Twin Falls County?

An occupied recreational vehicle may remain on an unincorporated Twin Falls County lot for no more than 90 days in a calendar year7. A tiny home is treated as a mobile or manufactured home only if it qualifies as one; in unincorporated Twin Falls County that placement needs an approved application to the County Building Department, a parcel that meets the zone's minimum lot size, and the single-family area and yard standards9. The unit must be at least 12 feet wide and 1,000 square feet, with a HUD label or the specified Idaho compliance certificate for homes manufactured before June 197689. We could not confirm a rule for other tiny homes, so ask Planning & Zoning to classify the unit before you buy28. A manufactured-home park requires a conditional use permit and health-district approval of its sanitation and layout42. Every manufactured-home installation must be inspected and approved by the state or local authority before occupancy43.

Building a home in Twin Falls County: the steps, in order

  1. Ask Planning & Zoning to identify the controlling county or area-of-impact code, mapped district, lot dimensions and overlays before design begins4628.
  2. Determine whether the site lies in a Special Flood Hazard Area; county permits are required before construction or development there44.
  3. Confirm access with the highway district serving the property and show the driveway or access road on the site plan45.
  4. Contact South Central Public Health District for the septic permit, and obtain an Idaho well-drilling permit if the project needs a well deeper than 18 feet513.
  5. Submit complete plans and supporting documents to the Building Department; complete residential review is usually estimated at no more than 7 business days26.
  6. Obtain separate electrical, plumbing and HVAC permits, complete state trade rough-ins before county framing inspection and trade finals before county final inspection, and secure occupancy approval before using the structure151646.

What should you check before buying land in Twin Falls County, Idaho?

About 8% of Twin Falls County soils rate ‘not limited’ for conventional septic drain fields, so resolve parcel-specific septic feasibility before buying41. Twin Falls County publishes separate preliminary-plat, final-plat, administrative land-division, conditional-use land-division and lot-line-adjustment applications47. A division into more than 3 parts for transfer or development is generally a regulated subdivision, subject to listed exceptions48. A subdivision or planned development within one-half mile of a municipality must connect to municipal water and sewer when the municipality allows it49. Check the mapped zoning district, applicable area-of-impact code, overlays and flood status before closing4644. A driveway must follow the serving highway district's rules, while state-highway access also needs an Idaho Transportation Department encroachment permit4550.

Watch-outs

  • Do not begin construction before the Twin Falls County building permit is issued16.
  • An occupied RV can stay on an unincorporated Twin Falls County lot for up to 90 days in a calendar year, not indefinitely7.
  • Do not treat an unincorporated parcel as unzoned: Twin Falls County zoning applies there, and an area of city impact may use city regulations adopted by the county3.
  • Idaho exempts qualifying owners who work on their own land and do not intend to sell within 12 months from contractor registration, but owner-builders still follow the permits and inspections that apply to their work1011.

Sources

  1. Residential Building Permit Information, quoted and re-checked
  2. Use and Occupancy of Buildings / Residential Building Permit Information, quoted and re-checked
  3. Twin Falls County Zoning Code, quoted and re-checked
  4. Area of Impact Codes and Maps, quoted and re-checked
  5. Twin Falls County Zoning Code 2022, quoted and re-checked
  6. Twin Falls County Zoning Code 2022, quoted and re-checked
  7. Twin Falls County Zoning Code, quoted and re-checked
  8. 8-8-3: Application Required, quoted and re-checked
  9. 8-8-3: Application Required, quoted and re-checked
  10. Contractors Archives, quoted and re-checked
  11. How To Purchase a Trade Permit (Idaho statewide rule), quoted and re-checked
  12. Twin Falls County Zoning Code, quoted and re-checked
  13. Wells Overview (Idaho statewide rule), quoted and re-checked
  14. twinfallscounty.org, quoted and re-checked
  15. Frequently Asked Questions (FAQs) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  16. Inspection Information, quoted and re-checked
  17. Use and Occupancy of Buildings / Residential Building Permit Information, quoted and re-checked
  18. Twin Falls: Permit Responsibilities and Requirements (Twin Falls County), quoted and re-checked
  19. Kimberly: Residential-Commercial Application for Building Permit (Twin Falls County), quoted and re-checked
  20. Buhl: 8-2-1: Permit Required (Twin Falls County), quoted and re-checked
  21. Hansen: 9-1-2: Building Permits (Twin Falls County), quoted and re-checked
  22. South Central Public Health District - Twin Falls Main Office (phd5.idaho.gov)
  23. Septic and Septage (Idaho statewide rule), quoted and re-checked
  24. Hansen: 8-3A-18: Private Sewer Permitted; Regulations (Twin Falls County), quoted and re-checked
  25. Twin Falls County Building Department (twinfallscounty.org)
  26. Residential Building Permit Information, quoted and re-checked
  27. Community Development Services, quoted and re-checked
  28. Twin Falls County Planning & Zoning Department (twinfallscounty.org)
  29. Twin Falls: Twin Falls, ID Laws (Twin Falls County), quoted and re-checked
  30. Kimberly: Kimberly, ID Laws (Twin Falls County), quoted and re-checked
  31. Buhl: 9-1-3: Jurisdiction (Twin Falls County), quoted and re-checked
  32. Filer: 9-3-1: Use Districts Established (Twin Falls County), quoted and re-checked
  33. Hansen: Ordinance No. 223 (Twin Falls County), quoted and re-checked
  34. Hollister: official source (Twin Falls County), quoted and re-checked
  35. Twin Falls County Zoning Code, quoted and re-checked
  36. Twin Falls County Zoning Code, quoted and re-checked
  37. Twin Falls County Zoning Code 2022, quoted and re-checked
  38. South Central Public Health District - Septic Records Portal (phd5.idaho.gov)
  39. Septic Records, quoted and re-checked
  40. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked
  41. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  42. Twin Falls County Zoning Code, quoted and re-checked
  43. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  44. Twin Falls County Zoning Code, quoted and re-checked
  45. Twin Falls County Zoning Code, quoted and re-checked
  46. Residential Building Permit Information, quoted and re-checked
  47. Applications, quoted and re-checked
  48. Twin Falls County Zoning Code, quoted and re-checked
  49. Twin Falls County Zoning Code, quoted and re-checked
  50. Types of Right-of-Way Encroachment Permits (Idaho statewide rule), quoted and re-checked

Written October 12, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

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Compared with neighboring counties

Like all 6 of its neighbors, Twin Falls County requires a building permit for a home.

RuleTwin Falls CountyJerome CountyGooding CountyLincoln CountyCassia CountyMinidoka CountyBlaine County
Building permitRequiredRequiredRequiredRequiredRequiredRequiredRequired
County zoningYesYesYesYesYesYesYes
Septic permitsSouth Central Public Health DistrictSouth Central Public Health DistrictSouth Central Public Health DistrictSouth Central Public Health DistrictSouth Central Public Health DistrictSouth Central Public Health DistrictSouth Central Public Health District

County locator

Twin Falls County in Idaho

50
County map
Twin Falls County highlighted among the Idaho counties · colored by Index score

How Twin Falls County scores

Seclusion66100% ev.
Self-Sufficiency20100% ev.
Admin Boringness3890% ev.
Durability68100% ev.
Property Autonomy90100% ev.
Carry Cost72100% ev.

Evidence strength: 98%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$385kTypical home
0.7%Property tax
$6,129Land / acre
12.6"Annual rain
21.6% of yrsSevere drought
5.2 / yr (+4.6)Mid-century 100°F days
31.9 daysMid-century dry spell
0.73" (+9.1%)Mid-century 1-day rain
1.14×Wildfire change factor
100%Forward climate coverage
$1,090Home insurance / yr
4.1% / yrInsurance growth
0.82%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
17,794Radius comparison (15 mi)
49.5People / sq mi
49.9%Federal land
82.9%Land at 15% slope or less
8.2%Soils rated "not limited" for septic (strict USDA rating)
99,825 acWorkable land screen
4.5%Wooded land
20.2 tonsBiomass / forest ac
48.1°FAvg temp

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Cities and towns in Twin Falls County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Not yet researched: Castleford · Murtaugh

Answers from the rulebook for Twin Falls County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Twin Falls County rules

  • Building permitRequired

    Buildings and structures subject to the Twin Falls County building-permit process.

    • The guide states that some types of work are exempt.
    • Accessory buildings under 200 square feet that are accessory to a residence do not require a permit.
    • Work must not begin before permit issuance; the minimum penalty for unpermitted work equals the building permit fee.

    accessory-building exemption threshold: < 200 square feet (Accessory to a residence)

    “A building permit is required any time a building or structure is erected, constructed, remodeled, enlarged, altered, repaired, moved, removed, converted, or demolished.”
    One more reviewed finding on this topic
  • Building code adoptedAdopted (with conditions)

    Construction within Twin Falls County jurisdiction.

    • The county states that the adopted codes are the 2018 editions with Idaho Amendments.
    • The list includes IBC, IRC, IECC, IMC, IFGC, IEBC, 2018 IFC with Idaho Amendments, and 2018 Idaho Manufactured Home Installation Standards.
    “Twin Falls County has adopted the 2018 versions, with Idaho Amendments, of the International Building Codes (IBC), International Residential Code (IRC), Energy Conservation Code (IECC), Mechanical Code (IMC), Fuel Gas Code (IFGC), International Existing Building Code (IEBC), 2018 Fire Code (IFC) with Idaho Amendments, and the 2018 Idaho Manufactured Home Installation Standards.”
    One more reviewed finding on this topic
    • Adopted (with conditions) — County-administered building regulation in Twin Falls County jurisdiction.
      “Twin Falls County has adopted the 2018 versions, with Idaho Amendments, of the International Building Codes (IBC), International Residential Code (IRC)”
  • InspectionsRequired

    Building inspections administered by Twin Falls County for permitted construction.

    • Inspection requests require the permit number, property address, contact person and phone number, and inspection type.
    • Inspections called in after 7:00 am are scheduled for the next working day.
    • Inspections typically occur Monday through Friday from 9:30 am to 4 pm, except holidays.
    • Before framing inspection, rough-in inspections for plumbing, electrical, gas, mechanical, fireplace, and firewall or sprinkler systems must be completed and signed off by the State of Idaho.
    • Before final building inspection, corresponding final inspections must be completed and signed off by the State of Idaho.
    • No work is to be done until the permit is issued.
    “Prior to requesting the final building inspection, the final inspections for plumbing, electrical, gas, mechanical, fireplace, and firewall or sprinkler systems must be completed and signed off on the construction card by the State of Idaho.”
    One more reviewed finding on this topic
    • Required — Building-permit construction and remodeling in county jurisdiction.
      “Prior to requesting the final building inspection, the final inspections [...] must be completed”
  • Certificate of occupancyRequired

    New or remodeled structures and specified changes of use in county jurisdiction.

    • An Occupancy Permit is required before use or occupancy of a new or remodeled structure.
    • An Occupancy Permit and, in some cases, a building permit is required before occupancy after specified changes of use.
    • A Certificate of Occupancy or occupancy approval may not be issued if a required inspection is incomplete.
    “require a final inspection and issuance of an Occupancy Permit”
    One more reviewed finding on this topic
    • Required — Use or occupancy of new or remodeled structures and qualifying changes of use.
      “Upon completion of a project and prior to occupancy of the premises, as specified in the adopted building code, the applicant shall secure an occupancy certificate.”
  • County-wide zoningPresent (with conditions)

    Twin Falls County zoning regulation in unincorporated portions of the county.

    • The county zoning code states that it is effective within unincorporated portions of Twin Falls County.
    • The code directs users to Title 10 to determine which portions apply within an area of city impact.
    • Official zoning maps adopted and signed by the Board of County Commissioners are incorporated into the code and maintained as official maps by Community Development Services.
    • This claim does not establish that the county zoning code governs incorporated municipalities generally.
    “This Zoning Code is effective within the unincorporated portions of Twin Falls County. To determine which portions of this Zoning Code apply in an area of city impact within Twin Falls County, please see Title 10.”
    One more reviewed finding on this topic
    • Present (with conditions) — Twin Falls County zoning regulation in unincorporated portions of the county.
      “This Zoning Code is effective within the unincorporated portions of Twin Falls County.”
  • Local zoningVaries (with conditions)

    Aggregate local zoning across Twin Falls County, including county zoning and municipal areas of impact; the county-level conclusion aggregates subordinate/local zoning systems and does not assert that the county administers every municipal ordinance.

    • Buhl, Filer, Hansen, Hollister, Kimberly, Murtaugh, and Twin Falls areas of impact have separately identified zoning codes or zoning materials.
    • Parcel-specific applicability depends on location and area-of-impact boundaries.
    “Buhl Area of Impact [...] Zoning Code Title 9 [...] Filer Area of Impact [...] Zoning Code Title 9 & 10”
  • Zoning districtsPublished (with conditions)

    County zoning districts and official zoning maps for unincorporated Twin Falls County.

    • The listed districts are Agricultural (A), Commercial (C), Industrial (I), Range Preservation (RP), and Rural Residential (RR).
    • The location and boundaries of each zone are shown on official Twin Falls County zoning maps.
    • The maps and all boundaries, notations, and other data shown on them are incorporated into the zoning code by reference.
    • The code's district publication does not establish the separate zoning rules applicable in every municipal area of impact.
    “A Agricultural Zone C Commercial Zone I Industrial Zone RP Range Preservation Zone (formerly known as the Agricultural Range Preservation Zone or ARP) RR Rural Residential Zone 8-6-2: MAPS ADOPTED: Zoning Map: The location and boundaries of each of the zones are shown on the official Zoning Map(s) of Twin Falls County, Idaho, and all boundaries, notations and other data shown thereon are incorporated by reference into this Title as if fully described herein.”
  • Minimum dwelling sizeSpecified

    Mobile homes and manufactured homes proposed for residential placement in the specified Twin Falls County zones.

    • The rule applies within the Agricultural Range Preservation Zone, Agricultural Zone, Rural Residential Zone, and Outdoor Recreation Overlay District where residential use is allowed.
    • County Building Department application acceptance and approval is required.
    • The unit must meet the applicable zone's minimum lot size and single-family dwelling area and yard requirements.
    • All listed construction, foundation, skirting, roofing, siding, HUD-label, and health/highway/canal approvals in Section 8-8-3 apply.

    minimum dimension: >= 12 feet · minimum floor area: >= 1000 square feet

    “The minimum dimension shall be twelve feet (12') with a minimum square footage of one thousand (1,000) square feet.”
  • Minimum lot sizeDistrict specific (with conditions)

    Lots in the Rural Residential (RR) zone and existing townsite plats governed by the county zoning code.

    • For RR lots using individual water and sewage systems, the lot must be at least one acre, subject to a plus-or-minus five-percent variation in platted subdivisions at Health Department discretion.
    • For lots served by public or private sanitary sewer and water, the RR minimum is 9,000 square feet.
    • Existing townsite plats have separate 12,500-square-foot or 9,000-square-foot standards depending on service.

    RR individual-system minimum lot area: >= 1 acre (Platted subdivisions may vary by plus or minus 5 percent at Health Department discretion) · RR public sewer and water minimum lot area: >= 9000 square feet · existing townsite minimum with public water: >= 12500 square feet

    “The minimum lot area per dwelling unit and for all other uses served by any public or private sanitary sewer and water supply system is nine thousand (9,000) square feet.”
    One more reviewed finding on this topic
    • Specified — Residential zoning districts in Twin Falls County Title 10, with district-specific dimensional standards.
      “The minimum lot area per household dwelling shall be one acre, or as set forth in the "Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems" as adopted by the South Central District Board of Health, whichever is larger.”
  • SetbacksSpecified

    Setbacks in the cited Twin Falls County Title 10 zoning district.

    • Front yards must conform to the stated standard or section 10-7-6, whichever is greater.
    • Double-frontage and corner lots require the front yard on both streets.
    • Accessory-building setback exceptions are provided by section 10-7-5.
    • The cited rural district requires 30 feet from front, rear, and other street frontages, and 7 feet for the side building line.

    front setback: >= 30 feet (double-frontage and corner-lot rules apply) · side building setback: >= 7 feet (architectural-projection and accessory-building rules apply) · rear setback: >= 30 feet (accessory-building rules apply)

    “The front building line shall not be closer than thirty feet (30') to the front property line.”
    One more reviewed finding on this topic
    • District specific (with conditions) — RR-zone setbacks and the Canyon Rim Overlay District in unincorporated Twin Falls County.
      “No dwelling, accessory building, or other structure shall be constructed or placed within fifty (50) feet of a canyon rim located in Twin Falls County.”
  • Lot coverageSpecified

    Lot occupancy/coverage for dwellings and accessory buildings in the cited Title 10 zoning district.

    • The cited limit applies to a specific zoning district and is not a uniform countywide percentage.
    • The rule applies to the dwelling including accessory buildings.

    maximum lot occupancy: <= 40 percent

    “No dwelling, including its accessory buildings, shall occupy more than forty percent (40%) of a lot.”
  • Building heightSpecified

    Building height in the cited Twin Falls County Title 10 zoning district.

    • The cited limit is district-specific.
    • Farm-produce storage is excepted in the cited district.

    maximum building height: <= 35 feet (buildings used for storage of farm produce)

    “No building shall exceed thirty five feet (35') in height except those used for the storage of farm produce.”
    One more reviewed finding on this topic
    • District specific (with conditions) — Structures in the Canyon Rim Overlay District.
      “The maximum allowable structure height within the Canyon Rim Overlay District shall be thirty-five (35) feet for any structure (measured from the existing natural grade of the property).”
  • Living in an RVTemporary only (with conditions)

    Occupied recreational vehicles placed on lots under the county zoning code.

    • An occupied recreational vehicle may not remain on a lot for more than 90 days in any calendar year.

    maximum occupied RV duration: <= 90 days per calendar year

    “No occupied recreational vehicle shall be placed on any lot for more than ninety (90) days within any calendar year.”
  • Tiny homesLimited

    Tiny homes that qualify as mobile homes or manufactured homes in unincorporated Twin Falls County.

    • Placement requires acceptance and approval of an application by the County Building Department.
    • Placement is identified for the Agricultural Range Preservation Zone, Agricultural Zone, Rural Residential Zone, and Outdoor Recreation Overlay District where residential use is allowed.
    • The parcel must meet or exceed the applicable zone's minimum lot size.
    • The unit must comply with the area and yard requirements for a single-family dwelling in the same zone.
    • Skirting, manufacturer-specified footing and foundation, permanent foundation anchoring, and specified roofing and siding requirements apply.
    • The home must bear the HUD acceptance label; homes manufactured before June 1976 must comply with Idaho Code chapter 25, title 44 and present a compliance certificate.
    • Health department, highway district, and canal company approvals must be secured.
    • Manufactured, mobile-home, and travel-trailer parks are conditional uses requiring a formal, previously advertised public hearing; additional sanitation, landscaping, recreation, density, and parking conditions may be imposed.

    minimum dimension: >= 12 feet · minimum floor area: >= 1000 square feet

    “The following uses of mobile homes and/or manufactured homes require the acceptance and approval of an application by the County Building Department (see Title 7, Chapter 1 of this Code):”
  • Manufactured homesLimited

    Manufactured/mobile-home parks in unincorporated Twin Falls County.

    • A manufactured/mobile-home park requires a conditional use permit from the Planning and Zoning Commission.
    • Sanitary facilities and layout require South Central Public Health District approval before application to the Board.
    • Park setback, parking, recreation, storage, and landscaping standards apply.

    park perimeter landscaped strip: 25 feet · front yard from park travel-way: >= 10 feet · side separation between homes/accessory buildings: >= 20 feet · rear yard: >= 5 feet (No additional rear yard setback where adjacent to the 25-foot perimeter area)

    “No manufactured and/or mobile home park shall operate without a conditional use permit granted by the Planning and Zoning Commission (“Commission”).”
  • Who permits septicLocal (with conditions)

    Approval authority for domestic or sewage-disposal facilities regulated by the Twin Falls County zoning code in unincorporated territory.

    • The county zoning code requires approval by the South Central Public Health District before domestic or sewage-disposal facilities may be installed or used.
    • The county code provision is expressly located in the county zoning code and therefore this claim is scoped to the unincorporated territory covered by that code.
    • The South Central Public Health District is the actual health-district authority named by the rule; the claim scope preserves the county-code geographic context.
    “No person shall install or use domestic or sewage disposal facilities until the same has been approved by the South Central Public Health District.”
  • Septic permitRequired

    Septic permitting records and requirements identified by the South Central Public Health District for Twin Falls County.

    • The official Health District page states that septic permits were not required before 1971, so older systems may lack records.
    • The page states that its septic records cover Twin Falls County and other counties served by the district.
    • This claim does not determine every permit exception under current state or district rules.

    permit requirement start: >= 1971 year (The source expressly states that septic permits were not required before 1971.)

    “Septic permits were not required before 1971. Information may not be available for older systems. Septic records on this site cover Blaine, Camas, Cassia, Jerome, Gooding, Lincoln, Minidoka, and Twin Falls Counties.”
  • Off-grid sanitationLimited

    Domestic or sewage-disposal facilities, including off-grid sanitation systems, in areas governed by the county zoning code.

    • No person may install or use domestic or sewage-disposal facilities until approved by the South Central Public Health District.
    • Where a public sewer or community sewerage system and treatment plant approved by the Health District is reasonably available, each lot's sewage-disposal system shall be connected to it.
    • The cited rule is within the county zoning code and is therefore scoped to unincorporated portions governed by that code.
    “Where a public sewer or community sewerage system and treatment plan approved by the South Central Public Health District is reasonably available for a lot, the sewage disposal system of each lot shall be connected thereto. No person shall install or use domestic or sewage disposal facilities until the same has been approved by the South Central Public Health District.”
  • Mandatory utility hookupConditional

    Water and sanitary-sewer connections for subdivisions or planned unit developments and sewer availability for lots.

    • A subdivision or planned unit development within one-half mile of a municipality must connect to municipal water and sanitary sewer if the municipality is willing to allow connection.
    • Where a public or community sewer system approved by the South Central Public Health District is reasonably available, each lot must connect to it.
    • Utilities may not be provided to a building, mobile home, or other structure until the utility company receives a copy of the building permit.

    municipal proximity threshold: <= 0.5 mile (Municipality must be willing to allow connection)

    “A developer of a subdivision or planned unit development located within one-half (1/2) mile of the incorporated limits of a municipality shall be required to connect to that municipality's services (water and sanitary sewer) provided that the municipality is willing to allow connection to its services.”
  • Subdividing landRegulated (with conditions)

    Platted subdivisions in unincorporated Twin Falls County.

    • A subdivision is a division of an original lot, tract, or parcel into more than three parts for transfer of ownership or development.
    • Platted subdivisions must comply with the county Title and applicable water/canal-company requirements.
    • Platted subdivisions are allowed only in zones where listed as an allowed or conditional use.
    • Exceptions include specified lot-line adjustments, estate distributions, court orders, condemnation, right-of-way acquisitions, and certain large agricultural parcels.

    subdivision threshold: > 3 parts (The code excludes specified land divisions from the definition.) · agricultural-zone parcel size exclusion: >= 40 acres (Plus or minus five percent.) · range-preservation-zone parcel size exclusion: >= 160 acres (Plus or minus five percent.)

    ““Subdivision” is synonymous with “platted subdivision” and is the result of division of an original lot, tract, or parcel of land into more than three (3) parts for the purpose of transfer of ownership or development. Any platted subdivision must comply with this Title and the requirements of applicable water/canal companies.”
    One more reviewed finding on this topic
    • Regulated (with conditions) — Subdivision and land-division processes administered through Twin Falls County planning and zoning.
      “Conditional Use Land Division [...] Land Division – Administrative [...] Subdivision Preliminary Plat [...] Subdivision Final Plat [...] Lot Line Adjustment in Platted Subdivision”
  • Driveway accessRequired

    Access to property and buildings in Twin Falls County.

    • Access must comply with the policies and regulations of the highway district where the property is located.
    • County permit materials also require driveway or access-road location, length, width, and type to be shown on site plans.
    “access to all property and buildings shall be in accordance with the policies and regulation of the highway districts in which the property is located.”
  • Building in a floodplainRequired

    Proposed construction and development, including manufactured-home placement, in Twin Falls County Special Flood Hazard Areas.

    • Twin Falls County permits are required before all proposed construction and development in Special Flood Hazard Areas.
    • State and/or federal permits may also be required when applicable.
    • Where no elevation data is available, building-permit applications must be reviewed for reasonable flood safety.
    • In zones A1-30 and AE without a designated regulatory floodway, new construction, substantial improvements, or other development including fill requires demonstration that cumulative development will not increase base-flood elevation more than one foot at any point within the community.

    maximum cumulative base-flood elevation increase: <= 1 foot (Applies in zones A1-30 and AE where BFEs are available and no regulatory floodway has been designated.)

    “Permits from Twin Falls County and, when applicable, state and/or federal agencies are required prior to all proposed construction and development, including the placement of manufactured homes.”
  • Permit feesPublished (with conditions)

    Building and zoning fees published by Twin Falls County.

    • The county Community Development Services page links a Building & Zoning Fee Schedule.
    • The opened fee document is titled for 2025; no newer fee schedule was established in this research.
    “Fee Schedule (Building & Zoning) [...] Building Applications [...] Inspection Information”
  • Permit processPublished (with conditions)

    County residential building-permit processing.

    • Complete plans and required supporting documents are reviewed in the order received.
    • The county guide estimates residential plan review at usually not more than seven business days when the submission is complete.
    • Additional state electrical, plumbing, and HVAC permits are required.
    • Permits expire after 180 days from issuance or the date of last inspection.

    estimated residential plan review: <= 7 business days (Complete plans, specifications, and supporting documents required) · permit expiration: 180 days (From issuance or date of last inspection)

    “The estimated time for a residential plan review is usually not more than seven business days. This is contingent upon the submittal of complete plans and specifications along with all of the required supporting documents.”

Idaho rules that apply here

  • Owner-builder exemptionConditional

    Homeowners personally performing plumbing work on their own residential premises in Idaho.

    • The homeowner must own the residential property and personally perform the permitted work.
    • The homeowner permit is valid only for a primary or secondary residence and associated outbuildings.
    • Associated outbuildings must not be used for commercial purposes or rented by a tenant.
    • The homeowner must accept responsibility for all work performed.
    • All work must be inspected by the Division of Occupational and Professional Licensing.
    • A plumbing permit must be obtained by application to the Division.
    • The application must be submitted with payment.
    • The application form states that an additional $65 fee may be assessed if the location is not clearly provided by directions or an attached map.
    • The application was revised 8/17/2022; this revision date is not treated as an effective date.

    unclear-location fee: 65 USD (May be assessed if the location is not clearly given by directions or an attached map.)

    “I certify that I am the owner of the residential property and will personally perform the work covered by this permit.”
    5 more reviewed findings on this topic
    • Available (with conditions) — An owner performing the owner's own work on the owner's own land under Idaho contractor-registration rules.
      “Owners: Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Available — An owner performing their own construction work on the owner's own land in Idaho.
      “A: Any person who engages in a construction job with a dollar amount exceeding $2000.00 (materials & labor) and is not otherwise exempt (The exemptions are listed below); [...] Owners: Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — An Idaho homeowner undertaking construction or trade work for which a state-administered permit process applies.
      “Public (Homeowners Only) [...] *Public: “Homeowner” is pre-selected. [...] Once payment is processed, you may choose “Request Inspection” and/or “Print Permit””
    • Conditional — Owners performing construction work on their own land in Idaho under the state contractor-registration system.
      “Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — Homeowners personally performing electrical work on a primary or secondary residence and related outbuildings in Idaho.
      “Homeowners may purchase a permit only when they themselves are doing electrical work on their primary or secondary residence and/or related outbuildings.”
  • Camping on your landLimited

    Camping or parking a vehicle or trailer on Idaho Fish and Game Wildlife Management Areas and access sites separate from a WMA.

    • The restriction applies in areas posted against camping or parking.
    • Leaving an unattended camp, vehicle, or trailer for more than 48 hours is prohibited without authorization.
    • Camping or parking for more than 10 days during any 30-day period on one WMA or one separate access site is prohibited without authorization.
    • The rule permits authorization by the Commission, Director, Regional Supervisor, or designee.

    unattended duration: > 48 hours (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.) · camping or parking duration: > 10 days during any 30-day period per WMA or separate access site (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.)

    “camp or park a vehicle or trailer for more than ten (10) days during any thirty (30) day period”
  • Accessory dwellingsLimited

    Accessory dwelling units for Idaho DEQ wastewater-flow and septic-system sizing purposes; this claim does not establish statewide zoning permission.

    • An ADU is sized as a single-family dwelling for the cited wastewater-flow guidance.
    • An ADU may combine flows with another structure into one system.
    • Any common septic tank must be large enough to hold the required capacity from both structures.
    • Local land-use, building, and septic authorities may impose additional requirements.

    wastewater flow basis: single-family dwelling

    “Size as a single family dwelling. Can combine with another structure's flows into one system”
  • Septic inspectionRequired

    Individual and subsurface sewage disposal systems constructed or installed under Idaho’s onsite wastewater rules.

    • The Director requires one or more inspections necessary to determine compliance.
    • The permittee must uncover or make available for inspection any portion covered or concealed in violation of the rules.
    • If preparation is required, the applicant or permittee must provide at least 48 hours’ advance notice, excluding weekends and holidays.
    • For individual systems, the public health district inspects the installation.
    • Large soil absorption systems are inspected by the public health district and DEQ.

    advance inspection notice: >= 48 hours (Excludes weekends and holidays.)

    “No system may receive wastewater until the Director conducts a final installation inspection”
  • Well permitRequired

    Construction or drilling of wells in Idaho, including domestic wells.

    • Before drilling, the well owner or driller must obtain a drilling permit from IDWR.
    • All wells must be constructed by a well driller with a valid IDWR license.
    • The separate water-right permit exemption for domestic purposes does not eliminate the drilling-permit requirement.
    • For new diversions in qualifying subdivisions filed on or after July 1, 2025, a water-right permit is required in a moratorium area, critical groundwater area, or groundwater management area, except for in-home uses and watering livestock.
    • Well construction rules apply to wells and other artificial openings more than 18 vertical feet below land surface.

    well depth threshold: > 18 vertical feet below land surface (The cited well-construction rules describe covered wells and artificial openings.) · subdivision application date: >= 2025-07-01 (Applies to qualifying new diversions described in Idaho Code § 42-227(4).)

    “Prior to drilling a well, the well owner or well driller must first obtain a drilling permit from IDWR.”
  • Campground & park staysLimited

    Temporary camping in Idaho State Parks administered by the Idaho Department of Parks and Recreation.

    • Camping is permitted only in designated areas.
    • Stays are limited to 14 nights in a 30-day period; the same page's FAQ separately states a 15-day limit, creating an unresolved internal discrepancy.
    • Individual-site occupancy is limited to one family unit or no more than 8 persons unless otherwise specified; companion-site and site-design restrictions apply.
    • Camping is not permitted on beaches, parking lots, or day-use facilities.
    • Check-in is at 2 p.m. for campsites and checkout is at 1 p.m.; late checkouts may incur additional fees unless prior arrangements have been made.

    state-park stay limit: 14 nights in 30 days (FAQ on the same page states 15 days in any 30-day period) · individual-site people limit: <= 8 people (one family unit or site-specific limits may apply)

    “Camping is permitted only in designated areas. [...] Stays are limited to 14 nights in a 30-day period.”
  • county zoning authorityGeneral

    Idaho counties adopting zoning for unincorporated areas through their boards of county commissioners.

    • A board of county commissioners is a governing board and may exercise the powers authorized by the Local Land Use Planning Act.
    • The county board's powers under the chapter apply to the unincorporated area of the county.
    • Zoning must be adopted, amended, or repealed by ordinance using the notice and hearing procedures in Idaho Code § 67-6509.
    • Zoning districts must conform to the adopted comprehensive plan.
    • Within zoning districts, standards may regulate or restrict building height, number of stories, size, construction, reconstruction, alteration, repair or use of buildings and structures; lot occupancy; courts, yards and open spaces; population density; and building and structure location and use.
    • Standards must be uniform for each class or kind of building throughout each district, but may differ between districts.
    • Overlay zoning districts require clear and objective standards and must not constitute a regulatory taking under Idaho or federal law.
    “The powers of the board of county commissioners conferred by this chapter shall apply to the unincorporated area of the county.”
  • county building authorityGeneral

    Idaho counties' authority to adopt and enforce building codes and require permits for residential construction in unincorporated areas when the county operates a building-code enforcement program.

    • The statute defines local government as any city or county of Idaho.
    • A local government that had not previously implemented a code-enforcement program may elect to implement one by ordinance evidencing its intent to do so.
    • Construction in a local-government jurisdiction enforcing building codes requires a permit under the applicable local ordinance.
    • A local government issuing permits and performing enforcement must adopt the specified state-adopted codes and may amend them only within the limits stated in Idaho Code § 39-4116(4).
    • Local amendments must generally provide at least an equivalent level of protection; accessibility amendments are restricted, and additional residential-code amendments require the statutory good-cause, necessity, ordinance, public-hearing, publication, and notice procedures.
    • Single-family homes and multiple-family dwellings up to two units are exempt from automatic fire-sprinkler requirements in the enumerated codes.
    • Agricultural buildings must be exempted; a county may issue farm-building permits only for road setbacks and utility easements, at no more than actual issuance cost.
    • Permits are governed by the laws in effect when the application is received.
    • The state division retains jurisdiction for in-plant inspections and installation standards for manufactured or mobile homes and for in-plant inspections and enforcement of modular-building and commercial-coach construction standards.
    “"Local government" means any city or county of this state.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Agricultural exemption — Agricultural building exemptions in Twin Falls County.
  • Short-term rentals — Short-term rental use in Twin Falls County.

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Water rights & wells in Twin Falls County

Whether a new home can legally get its own water here — the sub-state groundwater regime, from Idaho’s water agency.

Over-appropriated / declining

The aquifer here is over-appropriated and declining. A domestic well is usually still permit-exempt, but long-term supply is a genuine risk.

Household wellExempt — no permit or water right

Groundwater for domestic purposes up to 13,000 gpd is exempt from permitting; critical-area and moratorium closures generally target new PERMITTED (non-exempt) appropriations, so a household can still drill a domestic-exempt well even inside a critical groundwater area.

Limit: 13,000 gpd (homes, stockwater, irrigation of ≤0.5 acre) under Idaho Code 42-227

Idaho Dept of Water Resources — Domestic Exemption ↗

Prior-appropriation state (first in time, first in right). Groundwater rules change and basin boundaries follow the aquifer, not the county line — confirm current well and appropriation rules with the Idaho state water agency before you buy or drill.Groundwater governance as of Jul 2026, cited to each administering agency.

Living off-grid in Twin Falls County, Idaho

Is Twin Falls County a good place to live off-grid or homestead?

Twin Falls County scores 50/100 on the Bolthole Index, a solid county profile. Its strengths: a stronger property-autonomy legal backdrop and manageable long-term carry cost. Watch-outs: weak self-sufficiency basics: only 12.6″ of rain a year, in severe drought 21.6% of years and more administrative friction around building and land use.

Do you need a building permit in Twin Falls County, Idaho?

Twin Falls County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by South Central Public Health District (District 5). Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

Can you live in an RV or tiny home on your land in Twin Falls County?

Living in an RV on your own land in Twin Falls County is allowed on a temporary basis only: Occupied recreational vehicles placed on lots under the county zoning code. An occupied recreational vehicle may not remain on a lot for more than 90 days in any calendar year. A tiny home is limited to specific cases. Confirm with the county before relying on it.

How much does land cost in Twin Falls County, Idaho?

Land in Twin Falls County runs about $6,129 per acre, based on the latest county data.

What is the water situation in Twin Falls County?

Twin Falls County gets about 12.6" of rain a year, with severe drought in roughly 21.6% of years. On water rights, Twin Falls County lies in the Eastern Snake Plain Aquifer (ESPA) Ground Water Management Area — Designated a GWMA (2016); the Snake River Basin Moratorium (2022, amended 2024) bars new/pending permit applications above Swan Falls Dam, effectively closing new appropriative groundwater rights — domestic-exempt wells excepted..

How remote is Twin Falls County?

A typical private-land location has about 17,794 people within 15 miles and 1,083,906 within 100 miles. These radius catchments are the published fallback where road routing is unavailable.

How Twin Falls compares in Idaho

Compare side-by-side →See all 44 Idaho counties ranked →