Lava zones, water rights, agricultural zoning, and what most buyers miss — from a local Hawai'i Island Realtor.
Buying vacant land on the Big Island involves layers that simply don't exist on the mainland — and often don't exist on other Hawaiian islands either. The soil, the water, the roads, and the rock beneath your feet are all shaped by five active shield volcanoes and centuries of land use that range from traditional ahupua'a systems to modern agricultural zoning.
Before you fall in love with a parcel, you need to understand its lava hazard zone, how it gets water, what you can legally build, and whether the road in is actually yours to use. These aren't details — they determine whether a piece of land is a wise investment or a costly mistake.
This guide covers the four things every buyer must understand before making an offer on Big Island land.
The USGS assigns every parcel on the Big Island a lava hazard zone from 1 (highest risk) to 9 (lowest risk). This single number affects your insurance options, financing eligibility, and property value more than almost any other factor.
Directly over or adjacent to active rift zones. Includes lower Puna, Leilani Estates, Lanipuna Gardens, and areas around the East Rift Zone. The 2018 Kīlauea eruption destroyed 700+ homes here. Insurance is extremely limited. Most lenders will not finance.
Adjacent to Zone 1 and historically affected by frequent lava flows. Parts of lower Puna and areas around the Southwest Rift Zone fall here. Insurance options remain very limited — primarily Hawaii Property Insurance Association (HPIA) up to $450,000.
Parts of upper Puna and some South Hilo areas. Lower eruption frequency than Zones 1–2 but still carries volcanic risk. Insurance is available but limited. Some lenders will finance with additional requirements.
Covers North Kona, parts of Hilo, and mid-elevation areas. These zones have not experienced flows in recorded history but remain within the influence of active volcanic systems. Standard homeowners insurance is generally available here.
Includes Waimea/Kamuela, most of the Kohala Coast, and upper South Kona. Volcanic activity has not occurred here in thousands of years. Standard insurance and conventional financing are readily available.
The Kohala Mountain area on the island's northern tip — the oldest volcanic region, with no known eruption history. Easiest to insure, easiest to finance, and typically the most expensive land on the island due to its safety profile and scenery.
Important: Always verify a parcel's exact lava zone before making an offer. You can look up any address using the Hawaii County GIS system or ask your Realtor to pull the Tax Map Key (TMK) record. Zone determines insurance cost, financing options, and resale value — it is not a detail to skip.
On the Big Island, "does this property have water?" is a more complex question than anywhere on the mainland. There are three primary water systems, and which one a parcel uses affects both the cost to develop it and your daily quality of life.
Metered county water (provided by the Hawaii County Department of Water Supply) is available in established subdivisions, developed neighborhoods, and urban cores — primarily Kailua-Kona, Hilo, Waimea, and parts of the Kohala Coast.
If a parcel has a county water meter, that's the easiest and most reliable source. Check whether the meter is active and whether any outstanding water system fees are owed — these can transfer to a new owner.
In some rural subdivisions, county water lines exist but meters must be applied for — and there may be a wait list. Verify meter availability before closing.
Thousands of Big Island residents — especially in Puna and the Hāmākua Coast — rely entirely on rainwater collected from rooftops and stored in large above-ground tanks. This is not primitive: it is a fully functional water system when sized and maintained correctly.
Standard tank capacity: 10,000–30,000 gallons. Average household usage: 50–100 gallons per person per day. With 150+ inches of annual rainfall in some Puna areas, a well-maintained catchment system can be very reliable.
When buying a catchment home, inspect the tank (fiberglass or polyethylene, not rusted steel), the first-flush diverter, and the filtration system. Budget for a UV or reverse-osmosis filter for drinking water.
Wells are permitted in certain areas but require approval from the Hawaii Department of Land and Natural Resources (DLNR) Commission on Water Resource Management. Not all areas allow well drilling, and the process can take 6–18 months.
The cost to drill and develop a well on the Big Island typically ranges from $30,000–$80,000 depending on depth, location, and water quality. Some areas have brackish or saline groundwater — know your specific area before banking on a well.
If a seller claims a property "can have a well," always verify with the County Planning Department and DLNR before relying on that as your water plan.
The vast majority of vacant land on the Big Island is zoned agricultural. That doesn't mean you can't build — but it does mean what you can build, how large a lot you need, and what farming activities you must demonstrate are all governed by the county zoning code.
| Zone Code | Min. Lot Size | Dwelling Allowed? | Notes |
|---|---|---|---|
| FA-2a | 2 acres | Yes — 1 dwelling | Family Agricultural. Most accessible ag zone for residential development. Common in rural subdivisions near established areas. |
| A-1a | 1 acre | Yes — 1 dwelling | One-acre minimum. Permits agricultural activities plus a dwelling. More common in older ag subdivisions near town centers. |
| A-20a | 20 acres | Yes — with farming | Working farm designation. Must demonstrate active agricultural use to qualify for ag tax exemption. Common for serious farm operations. |
| A-40 | 40 acres | Yes — 1 per 40 ac. | Large ranch and farm parcels. One dwelling per 40 acres of land owned. Active agricultural operations required. |
| A-200a | 200 acres | Yes — limited | Large-scale agricultural operations. Rarely subdivided. Think legacy ranch land and large family holdings. |
Vacant land purchases on the Big Island require a different due diligence process than buying a home. There are fewer protections built in — no seller's property disclosure on some rural parcels, no automatic access to utility records. Here is what to verify before you commit.
Pull the Tax Map Key (TMK). This is the parcel's unique identifier. It shows legal size, zoning, ownership history, and recorded easements. Your Realtor can pull this from the County GIS portal.
Confirm access — legally, not visually. Just because there's a road doesn't mean you have a legal right to use it. Check the title for recorded ingress/egress easements.
Check for CPR designation. Condominium Property Regime lots subdivide a single parcel into individually owned portions. CPR properties have unique legal implications for financing and future subdivision.
Order a title search. Look for liens, unpaid property taxes, back water bills, and any encumbrances that would transfer to you at closing.
Confirm the lava zone. Look up the parcel at the Hawaii County GIS or ask for the USGS Lava Hazard Zone map. Never rely on the seller's verbal description alone.
Verify the water source. Is there an active county water meter? A working catchment system? A well permit? Or nothing — bare land with no water plan?
Check for electrical service. Is there HELCO power to the parcel, or is it off-grid only? If power lines don't reach the lot, factor in the cost of solar and battery systems before determining your price.
Confirm septic feasibility. County requires a percolation test before approving a septic system on undeveloped land. Hire a licensed engineer to run a perc test before you close.
Ask about conservation land or Special Management Areas. Some land near the coast or in upland forest areas falls under additional state restrictions that limit what you can build.
Land on the Big Island is uniquely complex — and the right guidance saves buyers from costly mistakes. Let's have a real conversation about what you're looking for before you make any commitments.