Building permits, zoning and septic rules in Honolulu County, Hawaii
48Index Score / 100 #4 of 5 in Hawaii
Honolulu County, Hawaii requires a building permit for work covered by its building code, subject to limited exemptions1. The City and County of Honolulu also sets zoning under Chapter 21 for every district and precinct on Oahu2. Septic permits are different: the Hawaii Department of Health, not the county, permits septic and other individual wastewater systems on properties without sewer service3.
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Do you need a building permit in Honolulu County (Oahu), Hawaii?
Yes. The City and County of Honolulu requires a building permit for work covered by its building code under Revised Ordinances of Honolulu Chapter 18, and a separate building permit is generally required for each building or structure121. Honolulu has adopted locally amended versions of the 2018 International Building, Residential and Existing Building codes13. A one-story detached accessory building serving a Group R-3 occupancy may be permit-exempt when it is used for storage, tools, a playhouse or a similar purpose and its total floor area does not exceed 120 square feet4. Hawaii's owner-builder license exemption is not a building-permit or inspection exemption, so an owner who builds personally still applies for the county permit and passes county inspections14. Permitted work remains subject to inspection, including a final inspection before final occupancy15. A building cannot be occupied, or its occupancy classification changed, until the Department of Planning and Permitting issues a certificate of occupancy16. Qualifying nonresidential agricultural structures may be exempt from a building permit and certificate of occupancy, but the exemption has notice, land-use, floodplain and utility conditions1718.
Who issues building permits in Honolulu County, and how do you reach them?
On Oahu the City and County's Department of Planning and Permitting handles building permits, and its Customer Service Division reviews and issues building permits for single-family and two-family homes, duplexes, and their accessory structures19. Reach the department at 650 South King Street, Honolulu, HI 96813, and call (808) 768-8220 specifically for residential building permits19. You can apply for an Instant Online Permit for many eligible single-family projects, or submit a full Internet Building Permit Application and receive an IBP number for projects that need plan review through the One-Stop Permit Center or Electronic Plan Review20. Permit fees are based on your project's fair-market labor and materials value rather than a flat schedule, so use the department's online fee calculator to estimate cost before you apply21. Septic permits do not come from this office; they come from the state Department of Health, covered below3.
Does Honolulu County have zoning?
Yes. Chapter 21 of the Revised Ordinances of Honolulu, the Land Use Ordinance, establishes zoning districts and precincts, allowed uses and structures, and zone-change procedures across Honolulu County222. The Department of Planning and Permitting's Land Use Permits Division administers the county's local zoning as well as shoreline and Special Management Area rules623. Every parcel also lies in a state Urban, Rural, Agricultural or Conservation land-use district9. Rural-district residential lots generally require one-half acre, subject to state and county exceptions24. The housing code requires at least one living-purpose room with 120 square feet; most other habitable rooms must have at least 70 square feet, while an efficiency dwelling has separate requirements25. Lot size, setbacks and building height vary by district, and residential zoning lots on Oahu are limited to 75 percent impervious surface, which counts paved areas and driveways as well as roofs26. Dividing or consolidating land requires subdivision review by the department27282930.
How do septic (IWS) permits work in Honolulu County?
The Hawaii Department of Health Wastewater Branch permits septic and other individual wastewater systems for Honolulu County properties that are not served by sewer3. Reach its Oahu/main office at 2827 Waimano Home Road, Ste 207, Pearl City, HI 96782, or (808) 586-429431. A licensed engineer must perform the percolation test, survey the property and submit plans to the Wastewater Branch, and the filing fee is $100 for a new system or $25 for an addition or modification32. No one may use the system until the director authorizes it in writing32. An individual system generally is limited to 1,000 gallons per day and five bedrooms, and dwelling developments generally need 10,000 square feet of land per system, subject to stated exceptions11. Composting and incinerator toilets treat toilet waste only, so shower and kitchen wastewater still needs approved treatment and disposal11. New cesspools are banned, and existing cesspools must be converted to an approved system by 205033.
Can you live in an RV or tiny home on your land in Honolulu County?
We could not confirm a Honolulu County rule that generally allows long-term RV living, private-land camping or a tiny home as a separate dwelling, so ask the Land Use Permits Division about the parcel and proposed use before buying23. Honolulu's Housing Code treats a stationary trailer, powered vehicle or recreational vehicle used for living as a building, and living in a vehicle not designed for living is a public nuisance; the code does not authorize RV occupancy in every zoning district34. Hawaii law limits habitation in a vehicle on public roads and requires the property owner's or occupant's authorization for both parking and habitation on private property, while allowing county ordinances to supersede that state rule35. A tiny home used as a dwelling still faces Honolulu's building-permit and zoning rules plus approved sewer or wastewater service12611. A pre-manufactured or mobile unit may serve as an accessory dwelling unit on a qualifying Residential or Country District lot if it meets the accessory-dwelling rules and applicable building codes36. Agricultural land leased under the state subdivision provision cannot contain permanent or temporary dwellings, trailers or campers37. Short-term rentals of less than 30 days are allowed only in resort-zoned and other eligible areas, and each unit must be registered38.
What are the steps to build a home in Honolulu County, in order?
Confirm the parcel's county zoning district and state land-use district with the Land Use Permits Division, including whether the proposal needs subdivision review23930.
If you will act as your own general contractor, register for Hawaii's owner-builder exemption, supervise the work and arrange licensed electrical and plumbing work; selling or leasing within one year after final inspection can create a presumption that the project was built for sale8.
Apply through the Department of Planning and Permitting's Customer Service Division, using an Instant Online Permit if eligible or the Internet Building Permit Application and plan review process otherwise1920.
Determine sewer availability; a municipal connection that increases sewage flow may require a Sewer Capacity Analysis, while an unsewered property needs state approval for its individual wastewater system3911.
Obtain a well construction and pump installation permit from the Hawaii Commission on Water Resource Management if the project includes a well40.
Complete required building and wastewater inspections, then obtain the certificate of occupancy and written approval to use the wastewater system before moving in151611.
What to check before you buy land in Honolulu County
Identify the parcel's county zoning district and state Urban, Rural, Agricultural or Conservation district before assuming a home or accessory use is allowed229. If Agricultural land is being offered through a lease subdivision, verify dwelling rights because the state provision can bar houses, trailers and campers on the leased area37. Check flood status early: property in a flood zone cannot use the Instant Online Permit path, and flood-hazard construction plans must show the applicable flood boundaries, elevations and proposed lowest-floor elevation41. Confirm legal access as well; work for a residential driveway inside a state highway right-of-way requires a state permit42. Budget carefully for wastewater because only about 13.1% of Honolulu County soils are rated without severe limitations for a conventional septic drain field43. If the property has a cesspool, include conversion by 2050 in the budget33.
Watch-outs
Hawaii bans new cesspools and requires existing ones to convert to an approved system by 2050; get a conversion estimate before closing on a property with a cesspool33.
A flood-zone property cannot use Honolulu's Instant Online Permit path and needs plans documenting the applicable flood hazards and elevations41.
We could not confirm a Honolulu County rule generally allowing long-term RV living or a tiny home as a separate dwelling on private land; ask the Land Use Permits Division about the parcel and proposed use23.
If your land is Agricultural and leased under Hawaii's agricultural-subdivision statute, no dwelling of any kind, including a trailer or camper, may be built on the leased parcel44.
Renting a unit for less than 30 days requires registration and is allowed only in resort-zoned and other eligible areas, so do not count on short-term rental income without a zoning verification38.
Written October 9, 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.
Honolulu County highlighted among the Hawaii counties · colored by Index score
How Honolulu County scores
Seclusion40100% ev.
Self-Sufficiency4062% ev.
Admin Boringness41100% ev.
Durability5893% ev.
Property Autonomy41100% ev.
Carry Cost32100% ev.
Evidence strength: 90%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →
$858kTypical home
0.3%Property tax
$29,887Land / acre
3.7% of yrsSevere drought
0 / yr (+0)Mid-century 100°F days
1.04×Wildfire change factor
80%Forward climate coverage
$2,068Home insurance / yr
2.5% / yrInsurance growth
0.28%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
54,156People within 30 min
1,019,302People within 2 hr
707,549Radius comparison (15 mi)
1,647.3People / sq mi
41.3%Land at 15% slope or less
13.1%Soils rated "not limited" for septic (strict USDA rating)
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Answers from the rulebook for Honolulu County
What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.
Honolulu County rules
Building permitRequired
Building construction and improvements subject to the City and County of Honolulu building code.
Building permits are required under ROH Chapter 18.
One-story detached accessory buildings for Group R-3 occupancies used for storage, tools, playhouses or similar do not require a permit when the aggregate floor area does not exceed 120 square feet.
Emergency work may begin without a permit only if the required building-permit application is submitted on the next working day.
A separate building permit is generally required for each building or structure.
Permit fees are based on project value, and plan-review fees apply when plans are required.
aggregate floor area exemption for qualifying detached accessory buildings: <= 120 square feet (Only for one-story detached buildings accessory to Group R-3 occupancies and used as storage, tools, playhouses or similar.) · emergency permit application deadline: next working day (Applies only to emergency work.)
“Building permits are required based on ROH Chapter 18.”
One more reviewed finding on this topic
Required — Construction work covered by the City and County of Honolulu building code on Oahu.
“A building permit is required to perform work covered by this code as provided in ROH Chapter 18.”
Building code adoptedAdopted
Building-code adoption by the City and County of Honolulu throughout Honolulu County, including construction governed by the Hawaii State Building Code, State Residential Code, and State Existing Building Code as locally amended.
Ordinance 24-15 adopts the Hawaii State Building Code, including the modified 2018 International Building Code, subject to City and County of Honolulu amendments.
Ordinance 24-17 incorporates City amendments to the 2018 International Residential Code and 2018 International Existing Building Code as adopted by the State Building Code Council.
Ordinance 24-17 took effect upon signature on June 25, 2024.
Ordinance 24-15 took effect August 9, 2024, 45 days after signature, for new permit applications.
Existing permit applications had until August 8, 2025 to be issued under the 2018 IBC with State Amendments.
The adopted code incorporates applicable local chapters and amendments, including Honolulu plumbing, fire, energy, existing-building, electrical, housing, and permitting provisions.
International Building Code edition: 2018 Edition (First Printing) (Modified by the Hawaii State Building Code and Honolulu amendments) · International Residential Code edition: 2018 Edition (Modified by the Hawaii State Residential Code and Honolulu amendments) · International Existing Building Code edition: 2018 Edition (Modified by the Hawaii State Existing Building Code and Honolulu amendments) · Ordinance 24-17 effective date: 2024-06-25 (Effective upon signature) · Ordinance 24-15 effective date for new permit applications: 2024-08-09 (45 days after signature) · Existing permit application transition deadline: 2025-08-08 (Applications could be issued under the 2018 IBC with State Amendments through this date)
“incorporating the City amendments to the 2018 IBC, 2018 IRC and 2018 IEBC [...] Ordinance 24-15 will take effect on August 9, 2024”
InspectionsRequired
All construction or work in Honolulu for which a building permit is required.
The work must remain accessible and exposed for inspection purposes.
The person doing permitted work must notify the building official when the work is ready for inspection.
The building official may require inspection requests to be filed at least one working day before the requested inspection.
A final inspection is required after all construction is completed and before final occupancy.
Lath and gypsum board inspection is required for fire-resistive construction, with an exception for lath and gypsum board installed in Group U occupancies.
Building permit-related inspections are conducted by the DPP Building Division, except inspections by the Honolulu Fire Department.
minimum inspection-request notice: >= 1 working day (The building official may require this notice.)
“All construction or work for which a permit is required shall be subject to inspection by the building official.”
Certificate of occupancyRequired
Use or occupancy of a building or structure, and changes in the existing occupancy classification, under the Honolulu residential building-code provisions.
No building or structure may be used or occupied, and no change in existing occupancy classification may be made, until the building official issues a certificate of occupancy.
The certificate is issued after inspection and a finding that there are no violations of the code or other laws enforced by the department.
A temporary certificate may be issued before completion of the entire permitted work only if the occupied portion is safe and complies with the code; the building official sets its validity period.
The certificate may be suspended or revoked if issued in error, based on incorrect information, or if the structure violates an ordinance, regulation, or code provision.
“No building or structure shall be used or occupied, and no change in the existing occupancy classification of a building or structure or portion thereof shall be made until the building official has issued a certificate of occupancy therefore as provided herein.”
County-wide zoningPresent
Zoning districts, precincts, permitted uses and structures, and zone-change procedures throughout the City and County of Honolulu.
Specific uses remain subject to the applicable zoning district, precinct, development standards, and permit procedures.
The official source describes Chapter 21 as the Revised Ordinances of Honolulu Land Use Ordinance.
“Chapter 21 of the Revised Ordinances of Honolulu, better known as the Land Use Ordinance (LUO), provides a list of zoning districts and precincts, the permitted uses and structures for each district and precinct, and the procedures under which applications for proposed zone changes are processed.”
Local zoningPresent
Local zoning administered by the City and County of Honolulu through the Land Use Permits Division across Honolulu County.
The Land Use Permits Division administers Chapter 21, the Land Use Ordinance.
Specific zoning permits, districts, precincts, and development standards may impose additional requirements.
“Administers Chapters 21, 25, and 26 of the Revised Ordinances of Honolulu, respectively the Land Use Ordinance, Special Management Areas Ordinance, and the Shoreline Setbacks Ordinance.”
Zoning districtsPublished
Zoning districts and precincts under Chapter 21 of the Revised Ordinances of Honolulu, administered by the City and County of Honolulu.
The Land Use Ordinance also identifies permitted uses and structures for each district and precinct.
Zone changes are amendments to the zoning ordinance adopted by the City Council to establish the affected zoning map.
A large-area landowner may alternatively seek a minor adjustment through a Zoning District Boundary Adjustment.
“Chapter 21 of the Revised Ordinances of Honolulu, better known as the Land Use Ordinance (LUO), provides a list of zoning districts and precincts, the permitted uses and structures for each district and precinct, and the procedures under which applications for proposed zone changes are processed.”
Minimum dwelling sizeSpecified
Dwelling units and congregate residences governed by the City and County of Honolulu building code.
At least one living-purpose room must be at least 120 square feet.
Other habitable rooms, except kitchens, must be at least 70 square feet.
If more than two persons occupy a sleeping room, the required floor area increases by 50 square feet for each occupant over two.
An efficiency dwelling unit is permitted as an exception only if it has a living room of at least 220 square feet, plus 100 square feet for each occupant over two.
An efficiency dwelling unit must also have a separate closet, required kitchen facilities with at least 30 inches of clear working space, and a separate bathroom containing a water closet, lavatory, and bathtub or shower.
Habitable rooms, other than kitchens, must be at least 7 feet in every dimension; the cited section also contains ceiling-height requirements.
minimum living-purpose room floor area: >= 120 square feet · minimum other habitable room floor area excluding kitchens: >= 70 square feet · additional sleeping-room area per occupant over two: per 50 square feet · efficiency dwelling-unit living-room floor area: >= 220 square feet (plus 100 square feet for each occupant over two)
“Every dwelling unit and congregate residence shall have at least one room for living purposes that shall have not less than 120 square feet of floor area. Other habitable rooms except kitchens shall have a floor area of not less than 70 square feet. Where more than two persons occupy a room used for sleeping purposes, the required floor area shall be increased at the rate of 50 square feet for each occupant in excess of two.”
One more reviewed finding on this topic
Specified — Dwelling units and congregate residences subject to Honolulu County Housing Code § 16A-4.3.
“Other habitable rooms except kitchens shall have a floor area of not less than 70 square feet.”
Living in an RVLimited
Human habitation in a stationary trailer, powered vehicle, or recreational vehicle on property in Honolulu County.
Honolulu's Housing Code treats a stationary wheeled structure or powered vehicle used for living purposes as a building.
Human habitation of a structure or vehicle that is not designed or intended for living, sleeping, cooking, or dining is a public nuisance.
This provision does not affirmatively authorize RV occupancy in every zoning district; applicable zoning, building, health, sanitation, and other requirements may still apply.
vehicle design/use requirement: Vehicle must be designed or intended for living, sleeping, cooking, or dining (Vehicles not so designed or intended constitute a listed public nuisance when used for human habitation.)
“The human habitation of structures or vehicles that are not designed or intended for living, sleeping, cooking, or dining;”
Manufactured homesAllowed (with conditions)
Pre-manufactured or mobile homes used as accessory dwelling units on qualifying Honolulu County lots.
The unit must comply with ADU provisions and all applicable building codes.
ADUs are limited to qualifying Residential or Country District lots with at least 3,500 square feet, adequate infrastructure, and no restrictive covenants.
Only one additional ADU is permitted.
The ADU or primary dwelling must satisfy the owner-occupancy requirement, subject to stated unforeseen-hardship exceptions.
An ADU may not be rented for less than six months.
minimum qualifying lot area: >= 3500 square feet (Residential or Country District lot) · maximum ADUs per lot: 1 ADU (in addition to the primary dwelling)
“Yes, these are just construction methods. They can be used as ADUs, provided they comply with the provisions related to ADUs and all applicable building codes.”
Mandatory utility hookupConditional
Projects in Honolulu County involving connection to the City and County of Honolulu municipal sewer system, particularly new sewer connections from unsewered lots and projects in areas with City-maintained or City-owned sewers.
A Sewer Capacity Analysis is required for projects that may increase sewage flow to the municipal sewer system.
The analysis form must be submitted for a new sewer connection from an unsewered lot, among other listed project types.
The City and County of Honolulu Wastewater Branch reviews sewer connection applications and projects in areas with sewers maintained or owned by the City and County.
Projects served by cesspools or septic tanks that are not connected to the municipal sewer system require approval by the State Department of Health.
“A Sewer Capacity Analysis is required for projects that may increase sewage flow to the municipal sewer system.”
Building in a floodplainLimited
Development and construction in flood zones and flood hazard areas within Honolulu County, including Oʻahu properties administered by the City and County of Honolulu Department of Planning and Permitting.
Instant Online Building Permits are unavailable when the property is in a flood zone; a Building Permit with plans is required instead.
For buildings and structures in flood hazard areas, construction documents must delineate flood hazard areas, floodway boundaries, flood zones, and design flood elevation as appropriate.
Construction documents must show the proposed lowest-floor elevation, including basement; for AO zones, the height above the highest adjacent grade; and, for coastal high hazard V Zones, the elevation of the bottom of the lowest horizontal structural member.
If design flood elevations are not included on the community's FIRM, the applicant must submit a flood study, flood data, and other pertinent information required by ROH Section 21, prepared by a licensed design professional, to the director.
DPP's Site Development Division processes flood reviews and inspections.
“For buildings and structures in flood hazard areas as established by ROH Chapter 21, construction documents shall include:”
Short-term rentalsLimited
Short-term rentals of less than 30 days in the City and County of Honolulu.
Short-term rentals are permitted only in resort-zoned areas and other STR-eligible areas shown by the City.
Each unit rented for less than 30 days must be registered.
Existing NUC holders and hotel and timeshare units are exceptions to the new registration system.
A written zoning verification request may be submitted if eligibility is uncertain; the stated cost is $300.
Registration is effective for one year and must be renewed annually before expiration.
rental period: < 30 days (Hotel and timeshare units and existing NUC holders are excepted from the new registration system.) · written zoning verification fee: 300 USD
“STRs are only permitted in resort-zoned areas, and as shown in Ordinance 25-52. Any owner or operator interested in renting out a unit within the STR-eligible areas for less than 30-days must register each unit to be rented for less than 30 days.”
Permit feesPublished (with conditions)
Building permit fees administered by the City and County of Honolulu Department of Planning and Permitting.
Fees are based on the project's fair-market labor and materials value.
A plan review fee applies when plans are required under Revised Ordinances of Honolulu Chapter 18.
Fees may be exempt depending on the scope of work under Chapter 18.
Separate building permits and fees are required for each structure.
fee basis: project value based on fair market labor and materials
“Permit fees are based on project value (fair market labor and materials). To calculate the fees, enter your project value into the Estimated Fee Calculator.”
Permit processPublished (with conditions)
City and County of Honolulu building permit applications and electronic plan review.
Applicants may submit an Instant Online Permit or a Building Permit depending on project type.
Instant Online Permits are generally for single-family dwellings and are unavailable when the property is in a flood zone or has an advisory or violation.
For a Building Permit, the applicant submits an Internet Building Permit Application, receives an IBP number, and submits plans through the One-Stop Permit Center or Electronic Plan Review.
OTR-60 is optional and limited to eligible detached single-family and two-family residential projects submitted through ePlans, including projects not located in a flood zone.
A separate building permit is generally required for each building or structure.
application channel: Internet Building Permit Application and ePlans or Instant Online Permit when eligible
“Yes. Depending on the type of project you are working on, you may submit for an Instant Online Permit or a Building Permit. To submit electronic plans, when you apply for a building permit select the Electronic Plan Review option.”
Owners or lessees building or improving residential or farm buildings or structures in Hawaii for their own use, or for use by their grandparents, parents, siblings, or children.
The owner or lessee must register for the exemption under HRS §444-9.1.
The building or structure must be for the owner's or lessee's own use, or for use by specified family members, and must not be offered for sale or lease.
The exemption does not apply to electrical or plumbing work required to be performed by licensed persons or entities unless the owner or lessee is licensed under chapter 448E.
The owner or lessee must supervise construction, hire appropriately licensed subcontractors for work requiring a license, ensure electrical and plumbing work is performed by appropriately licensed persons or entities, comply with applicable tax and workers' compensation requirements for unlicensed workers treated as employees, and comply with applicable laws, ordinances, building codes, and zoning regulations.
During construction, the owner or lessee must make the building-permit application, issued building permit, contracts, and proof of payment available for immediate inspection upon request.
After completion, those records must be maintained for three years and made available within seven business days upon request.
Sale, lease, or offering for sale or lease within one year after completion is prima facie evidence that the work was undertaken for sale or lease, subject to statutory exceptions for sales or leases to employees, work under an approved permit valued below $10,000, and eligible unforeseen hardship determined by the board.
An owner or lessee seeking an unforeseen-hardship determination must comply with the disclosure statement requirements and submit a written application with supporting documentation before selling, leasing, or offering to sell or lease; the board communicates its determination within 90 days of receiving a completed application.
Completion means the date of final inspection approval by the county.
An exempted owner or lessee is not eligible to recover from the contractors recovery fund.
The statute does not apply to agricultural buildings, structures, or appurtenances that do not require a building permit or are exempt from the building code.
post-completion record-retention period: 3 years (Records must be made available within seven business days upon department request.) · prima facie sale or lease period: 1 year after completion (Statutory exceptions include employee occupancy, approved-permit work valued below $10,000, and eligible unforeseen hardship.) · unforeseen-hardship determination response period: 90 days (Measured from receipt of a completed application.) · approved-permit valuation exception: < 10000 USD (Construction or improvements performed pursuant to an approved building permit.)
“This chapter shall not apply to owners or lessees of property who build or improve residential or farm buildings or structures on property for their own use, or for use by their grandparents, parents, siblings, or children, and who do not offer the buildings or structures for sale or lease; provided that:”
3 more reviewed findings on this topic
Available (with conditions) — Owners or lessees in Honolulu County who build or improve residential or farm buildings or structures for their own use or for use by their grandparents, parents, siblings, or children, subject to Hawaii's owner-builder exemption requirements.
“This chapter shall not apply to owners or lessees of property who build or improve residential or farm buildings or structures on property for their own use, or for use by their grandparents, parents, siblings, or children, and who do not offer the buildings or structures for sale or lease; provided that:”
Conditional — Owners or lessees performing contractor-regulated construction or improvement of residential or farm buildings or structures on property they own or lease, for their own use or use by grandparents, parents, siblings, or children, including an owner-occupant's primary residence.
“This chapter shall not apply to owners or lessees of property who build or improve residential or farm buildings or structures on property for their own use, or for use by their grandparents, parents, siblings, or children, and who do not offer the buildings or structures for sale or lease; provided that: (1) To qualify for an exemption under this section, the owner or lessee shall register for the exemption as provided in section 444-9.1;”
Conditional — Statewide owner-builder projects where the applicable county requires a building permit, including an owner's primary residence.
“A homeowner with an “owner-builder” permit is treated as the general contractor for the project and, as such, is responsible for ensuring the project meets county building codes, and complies with the permitting process, including having the project inspected by a county building inspector.”
Minimum lot sizeSpecified
Agricultural districts statewide; the exact agricultural-district minimum is determined by each county through zoning ordinance, subdivision ordinance, or other lawful means, subject to the state one-acre floor and statutory exceptions.
Each county determines the agricultural-district minimum lot size by zoning ordinance, subdivision ordinance, or other lawful means.
The minimum lot size for any agricultural use shall not be less than one acre, except as provided in §205-5(b).
A county may allow smaller lots for consolidation and resubdivision when it finds unreasonable economic hardship cannot otherwise be prevented or land utilization is improved, but the consolidation and resubdivision may not increase the number of lots over the number existing before consolidation.
A lot equal to or exceeding one acre may not be reduced below one acre through the consolidation and resubdivision action.
A county may also allow smaller lots for plantation community subdivisions, public, private, and quasi-public utility purposes, and lots resulting from subdivision of abandoned roadways and railroad easements.
minimum lot size for agricultural use: >= 1 acre (except as provided in section 205-5(b)) · lot-count change in consolidation and resubdivision: 0 additional lots (consolidation and resubdivision may not result in an increase in the number of lots over the number existing prior to consolidation)
“determined by each county [...] shall not be less than one acre”
3 more reviewed findings on this topic
Specified — Low-density residential uses in Hawaii rural districts.
“minimum lot size for any low density residential use shall be one-half acre”
Specified — Lots used for agricultural purposes in Hawaii agricultural districts.
“The minimum lot size in agricultural districts shall be determined by each county by zoning ordinance, subdivision ordinance, or other lawful means”
Specified — Residential lots in Hawaii rural land-use districts.
“Rural districts shall include activities or uses as characterized by low density residential lots of not more than one dwelling house per one-half acre”
Camping on your landLimited
Camping in Hawaii Forest Reserves administered by the Department of Land and Natural Resources, Division of Forestry and Wildlife.
A camping permit is required for all persons, groups, organizations, or associations wishing to camp within a Forest Reserve.
Camping is only allowed at official campsites.
“All persons [...] wishing to camp within a Forest Reserve are required to obtain a camping permit. Camping is only allowed at official campsites.”
Accessory dwellingsAllowed (with conditions)
Construction and residential use of accessory dwelling units on qualifying residentially zoned lots in Hawaii, subject to county ordinances and the statutory geographic and hazard exclusions.
Each county must adopt or amend accessory dwelling unit ordinances under HRS §46-4.8.
Except for the alternatives in subsections (c) and (d), county standards must allow at least two accessory dwelling units, or the reasonable equivalent, for residential use on all residentially zoned lots.
If a county uses the subsection (c) alternative, qualifying districts must be consistent with the county comprehensive general plan, reasonably distributed throughout the county's regional planning areas, and estimated to add development potential equivalent to half of the county's projected five-year demand stated in the 2019 Hawaii housing planning study.
The subsection (c)(2) alternative concerns districts within a reasonable walking distance of stations of a locally preferred alternative for a mass transit project and urban principal arterials situated within a primary urban area, urban core, or county equivalent identified by a county comprehensive general plan.
A county with a population of five hundred thousand or more must also address existing apartment or apartment mixed-use districts under subsection (d).
Accessory dwelling units remain subject to all development standards adopted by the respective county.
A county may deny permits when utility infrastructure is insufficient; after December 31, 2026, if a county has not adopted or amended zoning ordinances under this section, it may not deny an application for up to two accessory dwelling units solely because of the maximum number of housing units, but may deny based on infrastructure, design, or development standards.
The section does not apply outside the state urban district, to county powers within special management areas, or to urban-district areas the county deems at high risk of flooding, lava, or fire based on the most current federal or state data and maps.
The statutory definition of residentially zoned lot excludes county districts intended for rural, low density residential development and open space preservation.
The section does not create vested rights and does not preempt county authority to accept, review, approve, or deny permit applications.
minimum accessory dwelling units or reasonable equivalent: >= 2 units per qualifying residentially zoned lot (Subject to HRS §46-4.8(c)-(d) alternatives and exclusions.) · county zoning ordinance deadline: 2026-12-31 (If the county has not adopted or amended zoning ordinances under HRS §46-4.8.)
“Except as provided in subsections (c) and (d), each county shall adopt or amend ordinances [...] at least two accessory dwelling units”
One more reviewed finding on this topic
Allowed (with conditions) — Accessory dwelling units for residential use on residentially zoned lots within Hawaii urban districts, subject to county implementation and applicable county development standards.
“each county shall adopt or amend ordinances defining reasonable standards that allow for the construction of at least two accessory dwelling units”
Who permits septicState (with conditions)
Individual wastewater systems, including septic systems, serving properties in Honolulu County that are not serviced by a sewer system.
The Hawaii Department of Health Wastewater Branch administers statewide engineering functions for individual wastewater systems.
The Wastewater Branch states that its jurisdiction does not extend to properties serviced by sewer; wastewater issues for those properties are directed to the relevant county department or private sewer provider.
“The Wastewater Branch administers the statewide engineering functions relating to water pollution control, municipal and private wastewater treatment works, individual wastewater systems and the Clean Water State Revolving fund.”
One more reviewed finding on this topic
State — Statewide administration of individual wastewater systems, including septic systems, in Hawaii.
“The Wastewater Branch administers the statewide engineering functions relating to water pollution control, municipal and private wastewater treatment works, individual wastewater systems and the Clean Water State Revolving fund.”
Septic permitRequired
New or modified individual wastewater systems, including septic systems, in Honolulu County.
A licensed engineer must perform a percolation test, survey the property, determine wastewater requirements, and submit plans to the Wastewater Branch for review and approval.
Every applicant must pay a filing fee: $100 for a new individual wastewater system, treatment unit, or disposal system; $25 for an addition or modification to an approved or existing system.
No person may use an individual wastewater system until authorized in writing by the director.
No cesspool may be used as the wastewater system by any new building, and no new cesspool may be constructed after the rule’s effective date unless approved for construction before that effective date.
new IWS, treatment unit, or disposal system filing fee: 100 USD · addition or modification filing fee: 25 USD
“The application to construct a new individual wastewater system or to modify an existing individual wastewater system shall be made by the applicant on forms furnished by the director.”
One more reviewed finding on this topic
Limited — Construction or modification of an individual wastewater system, including septic tanks, statewide.
“No person shall construct, modify the construction of, or modify the use of a wastewater system without the approval of the director.”
Septic inspectionRequired
Construction and approval for use of individual wastewater systems, including septic systems, in Honolulu County.
The owner must resolve discrepancies recorded from inspections before written approval to use is issued.
The engineer must furnish a final inspection report within 30 days after construction completion, including certification of construction according to approved plans and an as-built plan.
The director may inspect the system or site at any time before approval and may require advance notice of the engineer’s inspection.
final inspection report deadline: 30 days after construction completion
“The engineer furnishes a final inspection report to the director within thirty days after the completion of the construction”
One more reviewed finding on this topic
Limited — New or modified individual wastewater systems statewide, including septic systems.
“The engineer furnishes a final inspection report to the director within thirty days after the completion of the construction which provides the following information:”
Off-grid sanitationLimited
Off-grid sanitation in Honolulu County where the property is not served by a sewer, including individual wastewater systems such as septic systems, aerobic treatment units, approved alternative systems, composting toilets, and incinerator toilets.
The Hawaii Department of Health Wastewater Branch is the statewide administrator for individual wastewater systems.
Individual wastewater systems may be used in remote areas and areas of low population density, but must comply with state wastewater rules and applicable county requirements.
Approved treatment equipment includes septic tanks, aerobic treatment units, passive aerobic systems requiring a septic tank, approved bioreactor gardens, composting toilets, and incinerator toilets.
Composting toilets and incinerator toilets treat only toilet waste; shower and kitchen wastewater still requires treatment and disposal.
An individual wastewater system generally may not receive more than 1,000 gallons per day and may not serve more than five bedrooms under HAR Chapter 11-62; Act 224, approved June 25, 2025, permits up to five bedrooms regardless of the number of dwellings, dwelling units, or accessory units, whether attached or detached, but does not apply to new requests to connect additional dwelling units to an existing cesspool.
For dwelling developments, the rule requires 10,000 square feet of land area for each individual wastewater system; total development generally may not exceed 50 single-family residential lots or 50 dwelling units except for developments consisting of one dwelling unit per acre or greater.
Lots generally must be at least 10,000 square feet, except lots created and recorded before August 30, 1991; for qualifying smaller lots, only one individual wastewater system is allowed.
No cesspool may be used as the wastewater system for a new building, and no new cesspool may be constructed after the rule's effective date unless approved for construction before that effective date.
No person may use an individual wastewater system until authorized in writing by the director.
Before approval to operate an individual wastewater system other than a cesspool, an operation and maintenance manual must be submitted and approved, and the owner must certify operation and maintenance under that manual.
A Hawaii-licensed civil engineer must develop the plan; after percolation testing, surveying, and determining wastewater requirements, the engineer submits plans to the Wastewater Branch for review and approval.
The State rules do not preempt consistent county plumbing, sewer-system, pretreatment, storm-sewer, or related requirements; properties served by sewer are outside the Wastewater Branch's jurisdiction for these onsite-system rules.
maximum wastewater flow per individual wastewater system: <= 1000 gallons per day (Buildings with highly variable flows are governed by separate provisions.) · maximum bedrooms per individual wastewater system: <= 5 bedrooms (Act 224 permits the five bedrooms regardless of the number of dwellings, dwelling units, or accessory units, but excludes new requests to connect additional dwelling units to an existing cesspool.) · minimum land area per individual wastewater system for dwelling developments: >= 10000 square feet (Older lots created and recorded before August 30, 1991 are excepted; qualifying smaller lots may have only one individual wastewater system.) · maximum development size: <= 50 single-family residential lots or dwelling units (Exception for developments consisting of one dwelling unit per acre or greater.) · Act 224 approval date: 2025-06-25
“No person shall use an individual wastewater system until authorized in writing by the director.”
Well permitRequired
Construction, modification, or sealing of water, production, exploratory, and monitor wells statewide.
The Commission on Water Resource Management administers the well construction permit requirement for water, production, exploratory, and monitor wells.
Injection wells instead require a State Department of Health permit.
Geothermal wells require a Department of Land and Natural Resources, Engineering Division permit.
Temporary test borings and test-boring sealings do not require a permit; permanent test borings for long-term monitoring are treated as monitoring wells and require a Commission permit.
Well construction, modification, or sealing work must be performed by a C-57 licensed well driller; pump installation work may be performed by a C-57, C-57a, or A-licensed contractor.
well driller license: C-57 · pump installer license: C-57, C-57a, or A
“In the State of Hawaii, work on water wells, production wells, exploratory wells and monitor wells requires a well construction permit from the Commission; work on injection wells requires a permit from the State Department of Health; and work on geothermal wells requires a permit from the Department of Land and Natural Resources, Engineering Division.”
One more reviewed finding on this topic
Required — Well construction, pump installation, and sealing of abandoned wells in Honolulu County.
“Application for a Well Construction/Pump Installation Permit **WCPI Permit requirement also applies to sealing abandoned wells.”
Agricultural exemptionConditional
Agricultural lands subdivided and leased for agricultural uses or activities permitted in HRS §205-4.5(a).
The principal use of the leased land must be agriculture.
No permanent or temporary dwellings or farm dwellings, including trailers and campers, may be constructed on the leased area.
Storage sheds, equipment sheds, and other structures appropriate to the agricultural activity carried on within the lot are not prohibited by the dwelling restriction.
Violations of the no-dwelling paragraph are subject to county enforcement authority and fines under §§46-4, 205-12, and 205-13.
The lease term must be at least as long as the greater of the county's minimum real-property-tax agricultural-dedication period or five years.
Lots created and leased under this section are legal lots of record for mortgage-lending purposes and are exempt from county subdivision standards.
minimum lease term: greater of county minimum real property tax agricultural dedication period or five years · dwelling construction on leased area: false (storage sheds, equipment sheds, and other structures appropriate to the agricultural activity are not prohibited)
“Lots created and leased pursuant to this section shall be legal lots of record for mortgage lending purposes and shall be exempt from county subdivision standards.”
Subdividing landLimited
Subdivision and leasing of agricultural lands for permitted agricultural uses under HRS §205-4.5(f).
The principal use of the leased land must be agriculture.
No permanent or temporary dwellings or farm dwellings, including trailers and campers, may be constructed on the leased area.
Storage sheds, equipment sheds, and other structures appropriate to the agricultural activity are not prohibited by this subsection.
Violations are subject to county enforcement authority and fines under HRS §§46-4, 205-12, and 205-13.
The lease term must be at least the greater of the county minimum real-property-tax agricultural-dedication period or five years.
Lots created and leased under this section are legal lots of record for mortgage lending purposes and are exempt from county subdivision standards.
minimum lease term: >= 5 years (The term must instead be at least the greater of five years or the county agricultural-dedication period.)
“Lots created and leased pursuant to this section shall be legal lots of record for mortgage lending purposes and shall be exempt from county subdivision standards.”
2 more reviewed findings on this topic
Regulated (with conditions) — Subdivision and leasing of agricultural lands for agricultural uses or activities permitted under HRS §205-4.5(a).
“agricultural lands may be subdivided and leased for the agricultural uses or activities permitted in subsection (a); provided that:”
Regulated (with conditions) — Subdivision and lease of agricultural lands within Hawaii agricultural districts.
“The lease term for a subdivided lot shall be for at least as long as the greater of:”
Driveway accessRequired
Routine construction involving residential driveways within the State highway right-of-way in Hawaii
The rule applies to ground disturbance within the State highway right-of-way.
The applicant must obtain clearance signatures from various utility companies.
Two sets of scaled construction plans are required, including a location map, existing highway facilities, and a traffic control plan.
Insurance is required.
The fee schedule varies and the minimum fee is $10.00.
A bond is required with a minimum of $1,000.00.
Three sets of plans, preferably 11 x 17, are required.
The DOT Best Management Practices form must be completed for review by the DOT Environmental section.
A Lane Closure Form must be completed two weeks in advance if proposed work involves lane or shoulder closures.
In most cases, review and processing occur within one week, depending on the work and BMP form complexity.
minimum fee: >= 10 USD (Fee schedule varies.) · minimum bond: >= 1000 USD · lane closure form lead time: 2 weeks (Required if proposed work involves lane or shoulder closures.)
“Routine construction projects within the State highway right-of-way consisting of ground disturbance of any kind: a. Residential driveways;”
county zoning authorityGeneral
Hawaii counties' zoning authority over lands outside forest reserve boundaries, including unincorporated county areas.
The authority applies to lands not contained within forest reserve boundaries established on January 31, 1957, or as subsequently amended.
Zoning must be accomplished within the framework of a long-range, comprehensive general plan.
The zoning power must be exercised by ordinance.
The statute identifies authority over agricultural, forestry, industrial, trade, business, residential, watercourse, special-restriction, building-location, height, bulk, setback, density, lot-coverage, open-space, lot-size, and use-duration matters.
The powers are to be liberally construed in favor of the county, subject to forest and water reserve limitations and the exceptions in HRS §46-4(c), (d), (g), and §46-4.8.
“The zoning power granted in this section shall be exercised by ordinance, which may relate to:”
One more reviewed finding on this topic
General — Hawaii counties adopting and enforcing zoning ordinances for lands within county jurisdiction, including unincorporated areas, subject to statutory exclusions and planning requirements.
“The zoning power granted in this section shall be exercised by ordinance, which may relate to:”
county building authorityGeneral
County authority statewide to enact and enforce building-related ordinances, including residential construction permitting and inspection measures, and to adopt, amend, and update county building-code ordinances within each county's jurisdiction.
County ordinance authority is subject to general law and may not be inconsistent with, or tend to defeat, a state statute whose text shows an express or implied intent to be exclusive or uniform statewide.
Each county must amend, adopt, and update the Hawaii state building codes as they apply within its respective jurisdiction, in accordance with HRS §46-1.5(13), without council approval.
Each county must adopt the HRS §107-25 codes and standards as referenced codes and standards for its county building-code ordinance no later than two years after adoption of the Hawaii state building codes.
If a county does not amend the Hawaii state building codes within the two-year period, the Hawaii state building codes become applicable as an interim county building code.
The statewide codes apply to all construction and include the International Residential Code.
county adoption deadline after adoption of Hawaii state building codes: 2 years (If the county does not amend the Hawaii state building codes within this period, they become an interim county building code.)
“The governing body of each county shall amend, adopt, and update the Hawaii state building codes as they apply within their respective jurisdiction, in accordance with section 46-1.5(13), without approval of the council. Each county shall amend and adopt the Hawaii state building codes and standards listed in section 107-25, as the referenced Hawaii state building codes and standards for its respective county building code ordinance, no later than two years after the adoption of the Hawaii state building codes.”
Inside cities and towns in Honolulu County
Municipal rules found while researching the county. They apply inside that city or town, not to unincorporated land.
Minimum lot sizeDistrict specific (with conditions)
Residential and other zoning-lot uses governed by the City and County of Honolulu Land Use Ordinance on Oahu.
The applicable minimum lot size depends on the zoning district and use.
The DPP FAQ states that an Ohana dwelling requires the legal lot of record to conform to the minimum lot size and dimensions for the district.
Other applicable Land Use Ordinance standards and infrastructure approvals may also apply.
minimum lot size: district-specific (Depends on zoning district and use)
“Ohana dwellings may be built in the agricultural, country and residential zoning districts (except in the R-3.5 Residential District), if the legal lot of record conforms to the minimum lot size and dimensions for the district.”
SetbacksSpecified
Residential dwellings on Oahu under the City and County of Honolulu Land Use Ordinance.
The general guideline is 10 feet from the front property line and 5 feet from side and rear property lines.
Side and rear yards must be larger when floor area ratio exceeds 0.6.
Article 3 of the Land Use Ordinance contains the applicable district-specific development standards.
front setback: 10 feet (General residential dwelling guideline; district-specific standards may apply) · side setback: 5 feet (General residential dwelling guideline; larger yards may apply when FAR exceeds 0.6) · rear setback: 5 feet (General residential dwelling guideline; larger yards may apply when FAR exceeds 0.6)
“In general, dwellings must be set back 10 feet from the front property line and 5 feet from the side and rear property lines. However, side and rear yards must be larger for floor area ratios exceeding 0.6. Please refer to Article 3 of the Land Use Ordinance for development standards.”
Lot coverageSpecified
Residential dwelling zoning lots on Oahu under the City and County of Honolulu Land Use Ordinance.
The cited requirement concerns total impervious surface area, including paved areas and driveways, rather than only building footprint.
The DPP FAQ identifies rooftops, walkways, patios, driveways, parking lots, impervious concrete and asphalt, and other continuous watertight pavement or covering as examples.
The ordinance may contain additional district-specific development standards and nonconforming rules.
maximum impervious surface area: <= 75 percent of zoning lot area (Applies to dwelling units constructed pursuant to building permits applied for after May 1, 2019, according to the cited ordinance text referenced by DPP)
“The total paved area including driveways shall not cover more than 75% of the lot. Impervious surfaces areas include, but are not limited to, rooftops, walkways, patios, driveways, parking lots, storage areas, impervious concrete and asphalt, and any other continuous watertight pavement or covering.”
Building heightDistrict specific (with conditions)
Residential rebuilding and new residential construction on Oahu under the City and County of Honolulu Land Use Ordinance.
Height requirements depend on zoning and the applicable development standards.
The DPP FAQ states that a legally permitted house may be rebuilt only if all Land Use Ordinance standards are met, including height.
District-specific standards are found in Article 3 of the Land Use Ordinance.
building height limit: district-specific (Depends on zoning district and applicable development standards)
“General development standards are contained in Article 4 of the LUO, and district-specific development standards are found in Article 3.”
Agricultural exemptionAvailable (with conditions)
Agricultural buildings or structures on farms and ranches in Honolulu County/Oahu that satisfy Hawaii Revised Statutes section 46-88 and are declared with the City and County of Honolulu.
The structure must be built in accordance with HRS 46-88.
The structure must be declared with the City and County of Honolulu.
If an existing declared exempt structure is altered in a way that no longer meets HRS 46-88, a building permit is required.
Exempt structures may not have plumbing or electrical work.
The submission requires a Declaration of Compliance with HRS 46-88, Certification of HRS 46-88 Exemption #12 as required, and a plot plan showing location, property lines, other structures, setbacks, and dimensions.
building permit exemption: true (Only for agricultural buildings or structures complying with HRS 46-88) · declaration: required (Declaration with the City and County of Honolulu is required)
“Agricultural building or structures built in accordance with Hawaii Revised Statues 46-88 are exempt from building permits. However, you must declare the structure with the City and County of Honolulu.”
Subdividing landRegulated (with conditions)
Subdivision and consolidation of land on Oahu administered by the City and County of Honolulu Department of Planning and Permitting.
DPP processes subdivision reviews and inspections.
Subdivision applications must comply with applicable subdivision rules and standards.
The cited street standards contain transition rules for applications submitted before their effective date, roadway master plans, and extensions or expansions of existing roadways.
The DPP may modify street standards under the Subdivision Rules and Regulations.
subdivision review: required (Specific exceptions and transition rules may apply under the subdivision regulations)
“The Site Development Division is responsible for the review, approval, and inspection of new subdivisions and their associated improvements;”
Still unanswered
We looked and could not find an official answer yet. Silence is not permission — ask the county directly.
Tiny homes — Occupancy of tiny homes in Honolulu 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 Honolulu County
Whether a new home can legally get its own water here — the sub-state groundwater regime, from Hawaii’s water agency.
Managed area
Groundwater is actively managed here, but a small household well is generally still available.
Household wellPermit required (issued by right)
No well may be drilled without CWRM permits (HAR 13-168), including inside a designated Ground Water Management Area. But individual domestic use and rain-catchment are EXEMPT from the Water Use Permit even inside a designated area (HRS 174C-48) — a household faces construction permitting, not appropriation permitting.
Limit: CWRM Well Construction + Pump Installation Permit required statewide before drilling
All of Oahu is a CWRM-designated Ground Water Management Area; new non-domestic sources need a Water Use Permit and the Pearl Harbor/Honolulu sectors are heavily allocated, but individual domestic users and rain-catchment are exempt (HRS 174C-48). A well-construction permit is still required.
Regulated-riparian state (large uses permitted). Groundwater rules change and basin boundaries follow the aquifer, not the county line — confirm current well and appropriation rules with the Hawaii state water agency before you buy or drill.Groundwater governance as of Jul 2026, cited to each administering agency.
Living off-grid in Honolulu County, Hawaii
Is Honolulu County a good place to live off-grid or homestead?
Honolulu County scores 48/100 on the Bolthole Index, a solid county profile. Watch-outs: higher long-term carry cost and its water supply.
Do you need a building permit in Honolulu County, Hawaii?
Honolulu County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by Hawaii State Department of Health - Wastewater Branch. 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 Honolulu County?
Living in an RV on your own land in Honolulu County is limited to specific cases: Human habitation in a stationary trailer, powered vehicle, or recreational vehicle on property in Honolulu County. Honolulu's Housing Code treats a stationary wheeled structure or powered vehicle used for living purposes as a building. Human habitation of a structure or vehicle that is not designed or intended for living, sleeping, cooking, or dining is a public nuisance. Confirm with the county before relying on it.
How much does land cost in Honolulu County, Hawaii?
Land in Honolulu County runs about $29,887 per acre, based on the latest county data.
What is the water situation in Honolulu County?
Water data for Honolulu County is limited. On water rights, Honolulu County lies in the Oahu Ground Water Management Area — All of Oahu is a CWRM-designated Ground Water Management Area; new non-domestic sources need a Water Use Permit and the Pearl Harbor/Honolulu sectors are heavily allocated, but individual domestic users and rain-catchment are exempt (HRS 174C-48). A well-construction permit is still required..
How remote is Honolulu County?
A representative private-land location has about 54,156 people within a 30-minute drive and 1,019,302 within two hours. The road-network catchments count population across county lines and clusters of smaller cities; straight-line radius values remain available as a comparison.
