Septic Installation & Cesspool Conversion in Eden Roc

We install septic systems and convert cesspools in Eden Roc, which is around a 25-minute haul for our machines coming up from Keaau. Eden Roc’s population roughly tripled between 2000 and 2020, and home values here run well below neighboring Mountain View and Fern Acres. On a tight budget, getting the wastewater right the first time matters even more.

Eden Roc Facts Worth Knowing

  • 1,386 residents and 629 housing units (2020 Census, Eden Roc CDP). The population was 451 in 2000 and 942 in 2010, so it roughly tripled in twenty years.
  • About 16 percent of housing units were vacant at the 2020 Census, compared with about 10 percent in Fern Acres next door.
  • Elevation: about 1,788 feet at the Census reference point. A listing on Palainui Avenue puts its lot at 1,700 feet.
  • Rain: on the Rainfall Atlas of Hawaii, the 180-inch line crosses Eden Roc, and one Palainui Avenue listing cites about 190 inches a year.
  • Lots: listings show lots of about an acre, and describe the typical Eden Roc lot as long and narrow.
  • Size: about 6.4 square miles, bordered by Mountain View to the north, Fern Acres to the east and Fern Forest to the west.
  • Lava: the state’s geologic map shows the 1400s Ailaau flows from Kilauea at the center of Eden Roc. USGS hazard mapping puts the subdivision in Zone 3.

Lower Prices, Same Septic Rules

Census Bureau survey estimates for 2020 to 2024 put the median value of owner-occupied homes in Eden Roc at about $165,000, compared with about $320,000 in Fern Acres and $357,000 in Mountain View. The same survey estimates a median household income of roughly $25,000, though the margin of error is large for a place this size.

That gap matters because a septic system doesn’t get cheaper when the house does. The rock, the permits and the fill cost about the same here as anywhere else on young Puna lava, and statewide a conversion typically runs $20,000 to $50,000. Next to a $165,000 home, that’s a big share of the value. Our conversion cost guide breaks down where the money goes.

That’s also why funding is worth a look here:

  • USDA Section 504 is built for very-low-income rural homeowners: repair loans of up to $40,000 at 1 percent, repaid over 20 years, plus grants of up to $10,000 if you’re 62 or older. The USDA office in Hilo can tell you whether you qualify.
  • The Act 204 (2026) state loan fund, run by the Hawaii Green Infrastructure Authority, isn’t open yet. HGIA expects a late 2026 launch.

There’s no state tax credit and no open DOH grant right now. See our grants and loans page for updates.

What’s Under an Eden Roc Lot

The Ailaau flows erupted from near Kilauea’s summit between about 1410 and 1460 AD and ran all the way toward the coast through lava tubes. Much of Eden Roc is still forest of ferns, ohia and waiwi growing on that lava. Six centuries isn’t much time to build soil, even in this much rain, so don’t count on deep dirt.

What that means for design:

  • The test pit rarely stays in soil. Your engineer has to log 5 feet of profile and run a perc test, and on lava this young, rock often shows up before the 5-foot mark.
  • Expect a soil replacement bed. Where the pit finds fractured lava, the state wastewater rules don’t allow effluent straight into the rock. The leach area is dug out and rebuilt with suitable fill, with a minimum of 3 feet between the system and groundwater.
  • Rain doesn’t stop. Wet weather affects excavation, how fill is placed and how the site drains afterward.
  • ATUs are an option, with strings attached. An aerobic treatment unit needs a service contract and inspections every six months for as long as it’s in use.

Narrow Lots, Few Paved Roads

An acre is about 43,500 square feet, more than four times the land the state asks for per system. Width is the issue. A leach field has to keep 5 feet from the house and from each side line, and a seepage pit 9 feet from the line. On a narrow lot, the house, catchment tank, driveway and field all compete for the same strip, so placement takes some planning.

Roads are the other thing to plan around. A listing describes Palainui Avenue as one of the few paved roads in the subdivision, and listings show road maintenance fees of about $50 to $60 a year. Off the paved routes, equipment travels on whatever surface the road has that season. When a county subcommittee studied upper Puna road links in 2015, it recommended finishing South Oshiro Road into Eden Roc Estates and linking Eden Roc to Fern Forest (Kaleponi to Punahele) and to the Kopua Farm Lots (Punahele to Apele). The report found that upper Puna’s subdivisions weren’t linked to each other, so equipment comes in from Highway 11.

When you call, tell us your street, whether it’s paved to your driveway and where on the lot the house sits. That tells us what size equipment and trucks can reach the site.

Typical Eden Roc Projects

  • New homes. Eden Roc went from 485 housing units in 2010 to 629 in 2020. For a new house, you need an approved system before the county will sign off on the building permit, and DOH reviews the wastewater plan first. Start with our septic requirements for a new home.
  • Replacing a cesspool. Older Eden Roc homes can still have one. One Eden Roc listing, for example, advertised a new permitted septic system installed in 2024, with the old cesspool pumped and backfilled. The state’s final deadline for the rest is the start of 2050.
  • Finishing a house that grew. Systems are sized by bedroom count, and the state presumes a bedroom for almost any room over 70 square feet. If a building permit adds bedrooms, DOH can require the cesspool to go.

Other Upper Puna Neighborhoods

Plan Your Eden Roc System

If you’re starting a new build or replacing a cesspool, we’ll look at the lot, the access and the rock, and help you line up the engineer and permits. Request a free estimate

Frequently Asked Questions

How much of my Eden Roc lot does a septic system need?

Land area is rarely the problem on an acre. The tight part on narrow lots is fitting the tank, leach field and side clearances next to the house and catchment.

My Eden Roc road isn’t paved. Can you still get equipment in?

Usually, but the road surface decides what size trucks and excavator we can bring, and wet weather matters. Tell us the route and any soft spots before the site visit.

Why does a septic system cost as much in Eden Roc as in pricier areas?

Home values reflect location and services. The septic rules and the rock are the same as anywhere on young Puna lava, so the system costs about what it would elsewhere.

Is there help paying for a system in Eden Roc?

Possibly. USDA Section 504 is aimed at very-low-income rural owners, and it covers rural areas like Eden Roc. The USDA office in Hilo can check your household against the income limits.

Does the young lava in Eden Roc mean I need a soil replacement system?

When the test pit hits fractured lava, yes. That’s a common result on young flows like the Ailaau, but your engineer’s profile and perc test make the call.

How do I know if my Eden Roc house has a cesspool?

Check county permit records, ask the seller, and look for a single buried pit with no tank and no leach field. Our buying and selling guide covers what to ask.