If you own a home in Puna, Hilo, Kona or Kaʻū, there is a good chance something under your yard has to go. It is a cesspool, the State says it must be gone by 2050, and on this island replacing one costs about $40,000. Here is the whole picture, first in a seven-minute video and then in writing, with a source for each number.
What the law actually requires
Hawaiʻi banned new cesspools in 2016. A year later, Act 125 required every existing cesspool to be upgraded, converted, or connected to a sewer. The date in HRS §342D-72 is January 1, 2050. A cesspool is basically a hole in the ground: raw sewage goes in and soaks away with almost no treatment.
Why this island carries more than half the load
Statewide there are about 83,000 cesspools, and about 48,600 of them are on Hawaiʻi Island, according to the State’s Cesspool Conversion Working Group. Together they put about 29 million gallons of untreated wastewater into the ground every day.
The island’s geology makes it worse. Young lava rock is cracked and porous, and water moves through it fast. At Puakō, UH Hilo scientists put dye into home wastewater systems and it came out of shoreline springs in as little as six hours. In front of 81% of the homes sampled, bacteria broke the State’s swimming standard. The same kind of dye work in Keaukaha and at Kahaluʻu Bay found sewage reaching the shore in hours to days. Is Hawaiʻi’s ocean full of sewage? has the details.
The place to pay particular attention is Puna: about 9,300 cesspools in a corridor 4.3 miles wide on Kīlauea’s east slope, roughly 17% of every cesspool in Hawaiʻi, in an area where many families rely on wells and rain catchment. When the Department of Health sampled domestic wells there, it found wastewater bacteria in a quarter of them.
Here is the strange part. The State’s priority tool puts 84% of this island’s cesspools in Priority 3, the lowest tier, which includes all of Puna. Priority 1 is just three areas: Kailua-Kona, Hōlualoa and Kawaihae–Waikoloa. But your tier does not change your deadline. Every tier shares one date: 2050. See What do the priority areas mean? for how to read it.
How is the cleanup going?
Slowly. Hawaiʻi Public Radio reported in June 2026 that, at the current pace, converting every cesspool in the State would take more than 200 years. For most families the bill has not come due yet. But it is sitting there.
What will it cost?
Hawaiʻi County’s 2025 cesspool task force put the median conversion at about $40,000, with an upper range around $70,000. The same report put the island’s median household income at about $74,600. That is more than half a year’s pay for something buried in the yard.
- Median conversion cost on Hawaiʻi Island (County Task Force, 2025)
- $40,000
- Median conversion cost on Hawaiʻi Island (County Task Force, 2025)
- Median household income on the island (same report)
- $74,600
- Median household income on the island (same report)
- The deadline for every cesspool (HRS §342D-72)
- 2050
- The deadline for every cesspool (HRS §342D-72)
What does it do to my home’s value?
Nobody can give you a number for your house, but the arithmetic is simple. In September 2026 the island-wide median single-family price was $502,000, according to Locations Hawaiʻi. On a $400,000 home in Puna, a $40,000 conversion is 10% of what the house is worth. On a $1.2 million home in Kona, the same job is closer to 3%.
The mandate costs about the same everywhere, so it bites hardest where homes cost the least. That is an illustration, not a prediction of what any one home will cost or sell for.
It bites hardest where homes cost the least.
What should a buyer know?
Nothing in State law requires a cesspool to be converted when a home is sold. This year, House Bill 1749 would have made sellers give buyers a cesspool disclosure form. It stalled in conference committee in April and never became law. So a buyer can close on a home without fully understanding the five-figure bill under it. If you are buying, ask what kind of system the home has and where it sits in the State’s priority tool before you sign.
Is there help paying for it?
A little, and it is not here yet. In July 2026, Governor Josh Green signed House Bill 1618 as Act 204, which creates a cesspool conversion loan fund run by the Hawaiʻi Green Infrastructure Authority. It can offer low-interest loans, and in some cases forgivable ones, with a preference for low- and moderate-income households. Lawmakers set aside about $2 million to start.
The catch: the authority’s director told Hawaiʻi Public Radio that $2 million will likely cover fewer than 100 conversions, statewide, and the fund is not taking applications yet. The goal is to launch by the end of 2026. Right now there are no State or County cesspool grants. The $10,000 tax credit expired in 2020 and the State’s pilot grant ended in 2024, as the Department of Health’s support programs page shows. For the full rundown, read How will we ever pay for a cesspool conversion?
The County is tackling a few problems of its own. In Pāhala, a $30.9 million project is building sewer lines to close large cesspools left from the sugar plantation days, under an EPA order, connecting 109 properties. The task force also looked at Puakō, Keaukaha, Miloliʻi and Kahaluʻu for community pilots. None of that is money for your house yet, but it is worth watching.
What should I do now?
The cesspool mandate is not a bill that shows up next month. It is a slow-moving cost, already sitting under tens of thousands of Big Island homes. So there is time to get ready, and the best first step is to find out what is in your yard: your State priority area, your distance to the ocean, and your depth to groundwater. Then keep an eye on the loan fund, because the early money will go fast.
ʻĀina Force coordinates. We don’t design, permit or install anything. Licensed, independent engineers and contractors do that under their own agreements with you. Our free property check shows your priority area, the ocean and nearby wells in about a minute, or you can call 808-ONE-WAVE.
