The information provided is accurate as of date published:

The State of Hawaii requires both grey water (sinks, washing machines, showers) and toilet waste to be included in a waste management system. Direct runoff into or onto ground is not allowed. 

If a composting, incineration or dry flush toilet exists in the home, a waste management system for the grey water must still be present or installed.

The State of Hawaii is requiring all cesspools be replaced with a septic system by the year 2050. 

Adding any additional living space to an existing home requires the cesspool be replaced before permits for the addition are approved. Adding an additional toilet etc to a cesspool is allowed.

On the Big Island, building a dwelling on agricultural land requires that the home be used as a "farm dwelling" directly tied to an active, income-producing agricultural operation. State and county laws strictly mandate that Ag-zoned land be prioritized for agricultural use, meaning pure residential housing or short-term vacation rentals are prohibited. Navigating Ag dwelling laws on the Big Island involves several specific rules and permitting hurdles:

• The Farm Plan Requirement: To build a home, you must prove the dwelling is an accessory to agricultural land conservation or production. This generally requires submitting a Farm Plan to the county, showing that a significant portion of the lot is in continuous agricultural productivity and generates income.
• Additional Farm Dwelling Agreement (AFDA): If you already have a primary residence on the lot and want to build another, you will likely need an AFDA. This legally binds the property to continued agricultural activity to justify housing for additional farm workers or family members.
• Vacation Rentals are Prohibited: The Hawaii Supreme Court has definitively ruled that farm dwellings in the agricultural district cannot be used as short-term vacation rentals or transient accommodations, as this does not align with the purpose of Ag land.
• Permitting Exemptions: You can build or place structures (under 500 sq ft) on Ag land without building permits, provided they are non-residential (no plumbing or electricity) and comply with maximum total footprint exemptions established by Hawaii Revised Statutes § 46-88
• State vs. County Zoning: Most Big Island Ag land falls under the State Agricultural District, which means strict state-level land use laws apply over county zoning. This frequently means you cannot build freely without state biosecurity or land use clearances

State Bill 123 allows property owners in eligible residential and agricultural zones to build up to three Accessory Dwelling Units (ADUs) per property. Units can be attached or detached, are limited to 1,250 square feet, and cannot be used as short-term vacation rentals. Specific laws and restrictions govern ADU construction on the Big Island:

• Zoning & Location: ADUs are primarily permitted in residential (including RS, RD, RA, A, and FA) districts and some agricultural zones. However, if your Ag-zoned land is located in a State Agricultural District (which applies to most Big Island Ag parcels), state law strictly requires dwellings to be used directly to support farm operations.
• Owner-Occupancy: Either the main house or one of the ADUs must be occupied by the property owner or a family member.
• Minimum Lease Term: Any ADU rented to non-family members must be leased for a minimum of 6 months. Short-term vacation rentals (like Airbnb or Vrbo) are strictly prohibited for ADUs.
• Infrastructure & Utilities: You must provide one off-street parking space per ADU. Additionally, you will need to meet Department of Health wastewater standards, meaning many rural properties will need to upgrade cesspools to septic systems to accommodate the added density.
• Kitchen Requirement: To qualify as an ADU (rather than a simple ohana or guest house), the unit must include a complete, independent kitchen with a full oven/stove rather than just a hotplate
• Infrastructure: You must prove you have adequate access to water and wastewater disposal. If you are off-grid, you need to manage your catchment and wastewater treatment.

State Bill 123 abolished the duplicative standalone Ohana permit, allowing you to build ADUs as long as you secure a standard Building Permit

To verify how your property is zoned, you can visit the County's TMK website at: 

https://qpublic.schneidercorp.com

1) Select the State, then Hawaii County, then click "Property Search"

2) Enter your address in "Search by Local Address"

3) Under "Parcel Information" find "Property Class " for your zone type