Water, Wastewater, and Power: A Big Island Home-Systems Primer

On the mainland, "what are the utilities?" is a formality. You assume city water, a sewer line, and a power meter, and you're almost always right. On Hawaiʻi Island, it's a real question with real money attached — and the answer changes from one subdivision to the next. I've had buyers fall for a place in Puna and only discover at the inspection that the "water" is a 10,000-gallon tank behind the carport. That's not a problem, exactly. But it's a thing you want to understand before you write the offer, not after.

Here's the broker's tour of the three systems that quietly decide a lot about a Big Island home: where the water comes from, where the waste goes, and how the lights stay on.

Water: county lines vs. catchment

Two homes a mile apart can have completely different water situations. In and around the towns — much of Hilo, Kailua-Kona, Waimea — homes are on county water, metered and piped like anywhere else. Out in the larger rural districts, especially Puna, parts of Kaʻū, and stretches of Hāmākua, the county main simply doesn't run down the road. Those homes catch their own water.

A rainwater catchment system is exactly what it sounds like. Rain hits the roof, gutters funnel it down, and it collects in a large tank — typically somewhere between 10,000 and 30,000 gallons. From there it's pumped into the house, usually through a sediment filter and some form of treatment (a UV light or similar) to make it potable. On the wet side of the island, where it rains a great deal, the supply is reliable in a way that surprises people. It's not roughing it; plenty of comfortable, fully modern homes run on catchment and have for decades.

But it changes the transaction in a few concrete ways:

• Lending and appraisal. Some loan programs want assurance that a home has a safe, potable, year-round water source. Catchment can absolutely qualify, but it's a question an appraiser and underwriter will ask, and a buyer's lender may want to see the system documented. It's smoother when the seller can show how it's set up and maintained.
• Insurance and maintenance. The tank, the liner, the pump, the filtration — they're owned systems that wear and need upkeep. A buyer is taking on that maintenance, and a smart one budgets for it.
• It's a value factor, not a flaw. Catchment isn't a deduction the way a failing roof is. It's a characteristic. Priced and disclosed honestly, it's simply part of what living in lower Puna costs and offers. The mistake is hiding it or hand-waving it.

If you're buying, ask for the tank size, the treatment setup, and the age of the pump. If you're selling, have those answers ready — it's the difference between a buyer who feels informed and one who feels ambushed.

Wastewater: sewer, septic, and the 2050 cesspool deadline

This is the system with a ticking clock on it. There are three ways a Big Island home handles wastewater, and they are not equal at resale.

Sewer connections exist in the urban cores — parts of Hilo and Kona town — and nowhere near most of the island. Septic systems are engineered, permitted, and generally fine; a buyer treats a properly functioning septic about the way they'd treat any mechanical system. The complicated one is the cesspool.

A cesspool is essentially a pit that lets untreated wastewater seep into the ground. Hawaiʻi relied on them heavily for generations, and the state now has more of them than almost anywhere in the country. The reckoning came in 2017 with Act 125, which requires every cesspool in Hawaiʻi to be upgraded — converted to a septic system, connected to sewer, or otherwise decommissioned — by 2050.

The scale of this is genuinely a Big Island story. Of the roughly 88,000 cesspools statewide, somewhere around 50,000 are on Hawaiʻi Island — more than any other county, and the most in the state ranked at the highest priority for conversion. The state has talked about getting the worst-polluting ones converted sooner, even by 2030, and there have been pilot grant programs to help with the cost. But the cost is real: converting a cesspool to a septic system commonly runs into the tens of thousands of dollars, depending on the site.

What does that mean when a home changes hands? A cesspool doesn't stop a sale, and the 2050 deadline is years out. But buyers are increasingly aware of it, and it comes up:

• A sharp buyer will ask what the wastewater system is, and may factor an eventual conversion into their offer.
• Some buyers — and occasionally a lender or an insurer — will want it addressed.
• A seller who already understands their system and the path to compliance negotiates from a much stronger position than one who's hearing "Act 125" for the first time across the table.

You can look up where a property sits on the state's cesspool priority list, and the Hawaiʻi Department of Health maintains the official guidance. If you own a home on a cesspool, knowing your priority tier and a rough conversion cost is worth doing before you sell, not because it's urgent today, but because it's one less unknown for a buyer to get spooked by.

Power: the grid, and going around it

Most homes here are on the HELCO grid like anywhere else. What's distinctly Hawaiʻi is how many homes generate their own power — and how that interacts with a sale.

Hawaiʻi has some of the highest electricity rates in the country, which is exactly why rooftop solar is everywhere, along with solar water heating, which is so cost-effective it's effectively standard on newer homes. The catch for buyers and sellers is in the details of how the solar is owned and what program it's on.

• Owned, paid-off solar is a clean win at resale. It conveys with the home, it lowers the electric bill, and there's nothing for the buyer to assume or qualify for.
• Leased solar or a power-purchase agreement (PPA) is more complicated. The panels belong to a third party, and at sale the buyer generally has to qualify to assume the lease or the seller has to buy it out. It's manageable, but it's paperwork and it can slow an escrow if nobody flagged it early.
• The interconnection program matters. Hawaiʻi closed its original net energy metering program to new customers back in 2015, and systems since then run on successor programs with different rules about exporting power to the grid. A buyer inheriting an older, grandfathered arrangement may be inheriting something genuinely valuable — worth knowing, and worth mentioning in the listing.

For homes truly off the grid — more common than you'd think in remote Puna and Kaʻū — power is solar panels plus a battery bank, and the buyer needs to understand the system's capacity the same way they'd understand the catchment tank. Again: not a flaw, just a system, and one that rewards an honest, well-documented handoff.

Why this is really a disclosure-and-marketing story

If there's a thread through all three systems, it's this: on Hawaiʻi Island, the systems are part of the property, and the sale goes well or badly depending on how openly they're handled. A buyer who gets clear answers about water, wastewater, and power up front stays calm through escrow. A buyer who discovers a cesspool or a leased PPA at the eleventh hour starts re-trading the price or walks.

That's a big part of why our intake asks about these systems specifically, and why Nalu can answer a buyer's catchment or cesspool question at eleven at night without waiting for anyone to wake up. Getting the facts out early isn't just good manners — it protects your price.

If you're trying to understand a specific area, our Puna district guide digs into how water, wastewater, and hazard stack up there, and the FAQ covers how we handle Hawaiʻi-specific disclosures. And if you're getting ready to sell, knowing your three systems cold is one of the most useful things you can do before you list — see how the 1% service works when you're ready.

General information for Hawaiʻi Island buyers and sellers, not legal, engineering, or financial advice. Programs and rules — Act 125 timelines, solar interconnection, lending requirements — change; confirm current specifics with the County of Hawaiʻi, the Department of Health, your lender, and a licensed inspector.