Cesspool Conversion Services in Hawaii
Hawaii Septic replaces cesspools with approved wastewater systems on every Hawaiian island. We handle the whole job: the site evaluation, the engineered design, the Department of Health paperwork, the excavation and install, closing the old cesspool, and the final approval that makes it official.
If you’re reading this, you probably know the basics already. State law requires every cesspool in Hawaii to be upgraded, converted or connected to a sewer before January 1, 2050. What most homeowners want to know is what the work involves on their lot, what it will cost, and how long it takes. That’s what this page covers.
Why homeowners convert now instead of later
Some owners convert because they have to. The Department of Health can require an upgrade when you pull a building permit that adds a bedroom, when a cesspool needs pumping more than twice in a year, or when it has spilled. Others convert because they’re selling, refinancing, or just tired of worrying about it.
Then there’s timing. The deadline is the same for roughly 83,000 cesspools statewide, and the number of engineers, licensed installers and DOH reviewers isn’t growing at the same pace. Owners who move early get more scheduling flexibility, and some may qualify for funding that tends to run out fast.
Our guide to Act 125 explains the law in detail, including what did and didn’t change in 2026.
What we replace your cesspool with
There’s no single replacement. The right system depends on your soil, groundwater, lot size, slope and how close you are to the ocean, streams or a drinking water well. These are the options we install most:
- Septic tank with a leach field. The standard choice where the ground and space allow. The tank settles out solids, and the leach field spreads the liquid into soil that finishes treating it.
- Septic tank with a seepage pit. Used in specific situations, such as steep lots or sites where good soil sits deep under a hard layer.
- Aerobic treatment unit (ATU). A tank with air pumped through it, which treats wastewater to a higher level. ATUs often fit sites with shallow groundwater or tight setbacks, and they need a service contract for as long as they’re in use.
- Soil replacement and mound systems. On fractured lava, Hawaii’s rules require the disposal area to be built in suitable fill. This is routine on much of the Big Island.
- Sewer connection. If a county sewer line runs past your property, connecting may be simpler than an on-site system. We’ll tell you if that looks like your best option.
How a conversion runs with us
- Site visit. We look at access, the lot, where the cesspool sits and what’s likely under the ground, then talk through realistic options.
- Engineering. A Hawaii-registered engineer runs the soil profile and percolation test and designs the system. Nothing gets designed until we know what the ground will actually do.
- DOH application. The engineer submits the plans to the Department of Health’s Wastewater Branch. We coordinate so you’re not chasing paperwork.
- Installation. Excavation, the tank or treatment unit, the disposal area and new piping from the house. On rocky lots, this is where heavy equipment earns its keep.
- Closing the old cesspool. It gets pumped out and filled so it can’t collapse or keep taking wastewater.
- Final inspection and approval to use. The engineer files the final report, and DOH issues the written approval that lets you use the new system.
For a deeper walkthrough of each stage, see our step-by-step conversion guide.
What it costs
Most cesspool conversions in Hawaii fall between $20,000 and $50,000, and difficult sites can run higher. The biggest swing factors are rock, groundwater, access and the type of system your lot needs. We give written estimates after a site visit, with each part broken out. Our cost guide shows where the money goes.
Help paying for it
Funding comes and goes. A state loan program created by Act 204 in 2026 is expected to open by the end of the year, and the USDA offers low-interest repair loans and small grants for some rural, lower-income homeowners. County grants open from time to time too. We keep a current list in our grants and loans guide, and we can help you time the work around a program.
Where we work
We convert cesspools across Hawaii, with our home base in Keaau on the Big Island. If you’re in East Hawaii, our pages for Puna and Hilo cover local soil, roads and permitting details for each community.
Ready to find out what your lot needs? Request a free estimate.
Frequently Asked Questions
Do I have to convert my cesspool right now?
Not necessarily. The legal deadline is January 1, 2050. But the Department of Health can require an upgrade sooner in certain situations, most often when a building permit adds bedrooms or the cesspool is failing.
How long does a cesspool conversion take?
It depends mostly on design and permitting. DOH review is often a matter of weeks, and installation usually takes days, though rocky or tight lots take longer. We’ll give you a realistic timeline after the site visit.
Can I keep using my cesspool while the new system goes in?
Usually, yes. The house stays connected to the cesspool until the new system is built and ready, and the switchover happens near the end of the job. We’ll explain any short interruptions ahead of time.
What happens to the old cesspool?
It’s pumped out and then filled completely so it can’t cave in or keep taking wastewater. The engineer records how it was closed in the final report to DOH.
Do you handle the permits?
Yes. We coordinate the engineering, the DOH application, the inspections and the final approval to use, so you’re not managing the paperwork yourself.
Can my cesspool connect to the county sewer instead?
Sometimes. If a sewer line runs near your property, connecting may be cheaper than an on-site system. We’ll check during the site visit, and you can confirm with your county’s wastewater office.