Septic Installation & Cesspool Conversion in Panaewa
We install septic systems and convert cesspools in Panaewa, a short run north on Highway 11 from where our excavators are parked in Keaau. Panaewa is the stretch of farm lots, homesteads and forest between Keaau and Hilo. A lot of the land here belongs to the Hawaiian Home Lands trust, and that changes who has to sign off before any digging.
Panaewa Facts for Planning a System
- Rainfall: about 150 inches a year, according to the Department of Hawaiian Home Lands’ 2015 environmental assessment for new Panaewa lots.
- Elevation: about 100 to 200 feet on the parcels covered by that assessment.
- Lava hazard: Zone 3 on the USGS hazard map, as cited in that assessment for its project area.
- Flood zone: FEMA Zone X (outside the special flood hazard area) for the same parcels.
- Water: county water lines run along Auwae Road and Mahiai Street.
- Homestead lots: the Panaewa house and farm lots were recorded in 1976. A DHHL planning document lists supplemental agricultural lots of about 1 to 12.5 acres, and residential homestead lots under half an acre.
Built on Hilo’s Biggest Lava Flow
Panaewa shares its name with Hilo’s biggest lava flow. USGS describes the Panaewa Forest Reserve flow as the largest in the Hilo area, a single long eruption from Mauna Loa about 1,500 years ago. It forms the coast from Waiakea Pond to Leleiwi Point, and USGS says that without it Hilo Bay wouldn’t exist.
Fifteen centuries isn’t long for soil to build on aa. On the ground here, the DHHL assessment maps the soil on its Panaewa parcels as Papai extremely stony muck. The federal soil description for the Papai series, whose reference site is just south of Hilo off Highway 11, shows:
- An organic layer on top, with fragmental aa starting around 10 inches down
- Solid bedrock around 53 inches
- Very rapid permeability through the soil and broken aa, and very slow permeability in the solid rock below
- 118 to 197 inches of rain a year across the series
Aa rubble drains fast, which is the problem: effluent can reach groundwater before it’s treated. The DHHL assessment places the area over the Hilo Aquifer System, where groundwater is mostly basal. That’s why the state rules for fractured lava point toward engineered soil replacement beds, not systems that drain straight into rock. Expect excavation into stony ground and imported fill.
Where Cesspools Are Already Off the Table
Statewide, no new cesspools have been allowed since 2016. Panaewa had extra restrictions even before that. In DHHL’s 2015 assessment for about 80 new half-acre lots, the planners noted that the Auwae Road parcels, near the transfer station, are in a Critical Wastewater Disposal Area, so “cesspools will not be allowed.” The parcel on Mahiai Street, near Highway 11, would have needed at least an acre for a cesspool under state rules.
DHHL’s answer was to require DOH-approved septic systems, designed and inspected by a licensed engineer, on the new lots. For the Auwae lots, it also planned “dry sewers,” lines put in the ground now so homes can connect if a sewer is ever extended there. That keeps the option open; it doesn’t mean a sewer is coming.
An older Panaewa home still on a cesspool faces the statewide January 1, 2050 deadline, or sooner if DOH requires an upgrade when bedrooms are added. To see how your parcel rates, use the University of Hawaii prioritization tool. Our walkthrough of the priority map shows how.
Hawaiian Home Lands Lessees: Check With DHHL First
If your Panaewa lot is a Hawaiian Home Lands lease, DHHL is the landowner, and its rules apply on top of the state septic rules. HAR 10-3-34 says no building, structure or improvement may be put on a homestead lot without written approval from the department. The lessee has to submit a plan showing the design, materials and use first. A new septic system is an improvement, so get that approval lined up alongside the DOH plan review.
Also worth knowing:
- Build to county code. DHHL requires structures on its subsistence agricultural lots to meet county code, and its general rules say the same for all homestead improvements.
- Lessees generally carry the cost. In notes from a 2025 DHHL community meeting about homestead cesspools (held for Waianae, on Oahu), the department said lessees pay for the line across their own lot, and that maintenance of an individual system falls on the lessee. DHHL also said it is looking for funding to help lessees with conversion, but it didn’t name a program.
- Loan help is still a proposal. In 2021 the Hawaiian Homes Commission advanced a proposed low-interest loan program for lessees with cesspools, then withdrew it to wait for the state cesspool working group’s recommendations.
For other money options, see our grants and loans page.
Newer Lots, Newer Projects
In July 2023, DHHL awarded the first 15 subsistence agricultural leases in Panaewa, half-acre lots meant for growing food, with six more planned. Lessees can build a home on them, so many of these lots will need a septic system designed from scratch.
That shapes the work we see most often here:
- New homes on half-acre agricultural lots, where the house, the garden beds, the animals and the leach field all have to fit together. Plan the septic location before laying out orchard rows or animal pens.
- Older farm-lot homes on cesspools that need conversion, sometimes on larger lots with longer runs from the house.
- Additions on homestead lots, which need DHHL approval for the building and may lead DOH to require a wastewater upgrade.
For how bedroom count sets tank and bed size, see our new construction septic guide.
Excavator Access on Farm Lots
Panaewa is a short drive from our yard, and lots near Highway 11 and the Panaewa Rainforest Zoo are easy to reach. Farm lots farther in can have long driveways, gates, orchard trees and soft ground after rain, so we check the route on the first visit.
Neighbors on the Hilo Side
See Keaau to the south, Keaukaha toward the coast, and Waiakea toward town. For an overview of the whole city, see Hilo septic services.
Walk Your Panaewa Lot With Us
Homestead lease or private land, we’ll walk the lot, check access, and work with your engineer so the DOH plans (and DHHL plans, if needed) match what can be built on this aa. Request a free estimate
Frequently Asked Questions
I’m a DHHL lessee in Panaewa. Do I need the department’s approval for a septic system?
Yes. Under HAR 10-3-34, any improvement on a homestead lot needs DHHL’s written approval, and the lessee submits plans first. Start that process at the same time your engineer prepares the DOH submittal.
Can I put a cesspool on my Panaewa ag lot?
No. The state stopped approving new cesspools in March 2016, and DHHL had already excluded them from its newer Panaewa lots in its own planning.
Will the dry sewers on the Auwae lots ever connect to anything?
DHHL put them in so a future connection would be possible, but we haven’t found any published plan to extend county sewer there. Plan for a working septic system now, and check with the county Department of Environmental Management for updates.
Why does Panaewa aa need special treatment if it drains so well?
Fast drainage isn’t the same as treatment. Fragmental aa can pass effluent toward groundwater before soil bacteria break it down. That’s why state rules for fractured lava call for an engineered soil replacement bed held well above the water table.
How does a half-acre subsistence lot affect the septic layout?
It’s enough room for a system, but you’re also fitting in crops and animals. Keep the system at least 5 feet from buildings and property lines, and keep heavy equipment and animals off the leach field once it’s built.
Who pays for a Panaewa conversion on Hawaiian Home Lands?
According to DHHL’s 2025 notes from a homestead cesspool meeting on Oahu, lessees generally pay for work on their own lot and for ongoing maintenance. DHHL said it is looking for funding help but hasn’t announced a program, so ask your DHHL district office what’s currently available.