Hawaii law requires every cesspool in the state to be converted by 2050. If your home has one, this guide covers what the law actually says, what converting costs, what your options are, and what financial help exists right now — in plain language, from a local company that works on cesspools every week.
Hawaii Cesspool Conversion Guide
The short version
- Every Hawaii cesspool must be upgraded, converted to septic, or connected to a sewer by January 1, 2050
- There is no requirement to convert today — but waiting has real costs
- A typical conversion runs $25,000–$50,000 depending on the property and the option
- A new state loan program launches in late 2026, with possible zero-interest loans for Oʻahu
- Until you convert, keep your cesspool pumped and get a straight answer on your options
What the law actually says
In 2017, Hawaii passed Act 125, which requires every cesspool in the state to be upgraded, converted, or connected to a sewer system by January 1, 2050. Hawaii was also the first state to ban new cesspools, back in 2016.
The reason is scale. Hawaii has roughly 88,000 cesspools — more than any other state — and every one of them releases untreated sewage directly into the ground. On Oʻahu alone, about 11,300 cesspools put an estimated 7.5 million gallons of untreated wastewater into the ground every day. That wastewater does not disappear: it moves into groundwater, where much of our drinking water comes from, and out to the reefs and beaches.
Nobody loves the price tag, but the direction is set. The cesspool era in Hawaii is ending — the only question for homeowners is when, and on what terms.
How to find out if your home has a cesspool
Many Oʻahu homeowners honestly are not sure what is under their yard. There are a few ways to find out:
- Your property documents — closing paperwork or a past inspection usually names the system
- State records — the Department of Health keeps records of registered cesspools
- The University of Hawaiʻi Sea Grant cesspool map, which shows locations and priority levels
- Ask us — if we pump your system we can tell you exactly what you have, at no charge
Do I have to convert right now?
No. As of mid-2026 the only deadline in law is 2050, and there is no requirement to convert when you sell a home — though sellers must disclose a cesspool, and buyers increasingly factor the conversion cost into their offers.
But here is the honest picture of why leaving it until 2045 is a risky plan:
- Deadlines may move up — lawmakers keep proposing 2035–2040 for high-priority areas
- Hawaii converts only about 400 cesspools a year; at that pace 88,000 would take over two centuries
- As 2050 nears, tens of thousands of owners will compete for the same contractors and permits
Your three conversion options
Every property is different, but conversions come down to three paths. Typical Hawaii conversions run $25,000–$50,000; the right option — and the real number — comes from a site and soil assessment, not a guess over the phone.
- Connect to the county sewer — cleanest long-term answer where a main runs nearby
- Install a septic system — the most common and usually most cost-effective conversion
- Install an aerobic treatment unit — for small lots, poor soils, or shoreline properties
- Cost depends on lot size, soil, and distance to a sewer main
- A site and soil assessment tells you which one your property can actually support
What financial help exists right now
This is the part of the picture that changes most often, so here is where it stands as of mid-2026:
- New: the state Cesspool Conversion Revolving Loan Program, launching by the end of 2026
- It is funded with $2 million in state funds plus $625,000 from the City and County of Honolulu
- Because of Honolulu’s contribution, Oʻahu owners applying before 2030 may qualify for zero-percent interest
- Expired: the old $10,000 state tax credit (ended 2020) and the $20,000 pilot grant program
- Proposed but not yet passed: a new tax credit covering 35% of conversion costs
What converting actually looks like
A typical conversion project on Oʻahu runs through six stages. End to end most take a few months — and most of that is design and permitting, not construction.
- 1. Site and soil assessment — what you have, where the space is, what the ground supports
- 2. System design — an engineer designs the septic system, ATU, or sewer connection
- 3. Department of Health permit — the design is approved before any digging
- 4. Installation by a licensed contractor
- 5. Cesspool closure — the old cesspool is pumped out and properly closed
- 6. Final inspection and sign-off
Until then: take care of the cesspool you have
Conversion is a when, not an if — but until it happens, a maintained cesspool protects your property and keeps your household out of emergency territory. That means pumping every one to three years depending on size and use, and paying attention to the early warning signs: slow drains, gurgling plumbing, odors, or soggy ground near the cesspool.
That is the work we do every day, all over Oʻahu. We handle cesspool pumping and service now, and septic system installation and replacement when you are ready to convert.
Frequently Asked Questions
Is the 2050 cesspool deadline real?
Yes. It has been state law since 2017, and the state is now funding conversion programs — the direction is not changing. If anything, deadlines for high-priority areas may move earlier.
Can I sell a home with a cesspool?
Yes. There is currently no conversion requirement at sale, but you must disclose the cesspool, and buyers increasingly negotiate the conversion cost into the price. Bills requiring conversion at point of sale have been proposed, so this could change.
How much does a cesspool conversion cost in Hawaii?
Most Hawaii conversions today run $25,000 to $50,000, depending on the property and the type of system. A site assessment gives you a real number.
Which conversion option is right for my property?
It depends on whether a sewer main is nearby, your lot size, your soil, and how close you are to the water. That is exactly what a site and soil assessment answers.
Is there financial help for cesspool conversion?
Yes. A new state loan program launches in late 2026, with possible zero-percent loans for Oʻahu homeowners who apply before 2030. Older grant and tax-credit programs have expired, and a new tax credit has been proposed.
What happens if I do nothing?
Until 2050, nothing — as long as your cesspool keeps working. But a failing cesspool is a health hazard and an emergency expense, and homeowners who wait until the deadline crunch will convert at the worst prices in the tightest market.