4 Things Buyers Often Miss About the Big Island

It's easy to fall for a Big Island listing on a screen, especially from thousands of miles away. The photos look perfect. The price looks reasonable. Then escrow starts and a few things show up that nobody flagged ahead of time. Here are four things buyers often miss, and how to check them before you write an offer.

Your water might come from the roof

Plenty of West Hawaiʻi neighborhoods have no county water hookup. Homes run on catchment systems instead. Rain collects off the roof into a tank, then gets filtered and pumped into the house.² It works well once you understand it, but it is not the same as turning on a tap connected to a municipal line. Ask your agent whether a property is on county water, a private system, a private well, or catchment, and ask to see the filtration setup before you assume anything. Each of my area guides lists the public water systems that serve that part of the island.

Check what is under the yard

Many properties here are not on sewer. They run on septic or on an older cesspool. Under Hawaiʻi's Act 125 (2017), every cesspool in the state must be upgraded to septic or another approved system, connected to sewer, or closed by January 1, 2050, and the Department of Health ranks some areas as higher priority for upgrades.¹ Ask for the seller disclosure, specifically the wastewater question on Hawaiʻi's RR105c form, and ask for pumping records if a cesspool is involved. This is market commentary, not legal advice. Confirm the compliance timeline for a specific property with the Hawaiʻi State Department of Health's Wastewater Branch.¹ More on this in my moving guide.

Know your lava zone before you fall in love

USGS maps Hawaiʻi Island into lava-flow hazard zones numbered 1 through 9.³ Most of Kailua-Kona and Keauhou sit in Zone 4, where standard homeowners insurance and normal financing are generally available. It is Zones 1 and 2, on and near the summits and rift zones of Kīlauea and Mauna Loa, where coverage gets expensive or some lenders walk away entirely. Get the zone for the exact parcel before you fall for the view. My lava zone guide breaks it down area by area.

Do not assume the rental rules are settled

If part of your plan is short-term rental income, know that the rules are still moving. Bill 147 picked up an unfavorable committee vote on October 6, 2026, then passed first reading before the full Hawaiʻi County Council on October 21. It still needs a second reading.⁴⁵ I cover the details in my Bill 147 guide. Whatever is true today could look different in six months. Buy the property on its own merits, not on a rental number someone promised you, and confirm current short-term rental status with the County before you count on anything. My vacation rental guide walks through zoning, registration and taxes.

None of this means skip the Big Island. It means do the homework before you fall in love with a photo. That is exactly what I help buyers do: separate the real opportunities from the ones that only look good online.

A shorter version first went out in my Monday note on Substack on Oct 19, 2026 (original ↗). This page is the updated, sourced version, last reviewed November 2, 2026.

General information only, not legal, tax, insurance or lending advice. Facts reviewed against the cited sources on November 2, 2026; rules and rates change. Hayden Fennoy is a REALTOR® (S) with eXp Realty, not an attorney or tax professional. Verify any specific property with the appropriate County or State office and your own advisors.