Septic Installation & Cesspool Conversion in Hawaiian Paradise Park

We install septic systems and convert cesspools in Hawaiian Paradise Park, about 5 miles down Highway 130 from Keaau, where our equipment yard is. HPP is among the largest subdivisions in Hawaii, and two things shape almost every septic job here: one-acre lots on young pahoehoe with little or no soil, and households that get their drinking water from their own roof or their own well.

HPP by the Numbers

  • Population: 14,957 in the 2020 Census, up from 11,404 in 2010. That is roughly 30 percent growth in ten years.
  • Housing units: 5,745 in 2020, up from 4,526 in 2010.
  • Lots: 8,843, according to the owners association’s history page. Most are about one acre. Lots were first marketed in the late 1950s, ahead of statehood, and the subdivision sold out in 1967.
  • Elevation: from sea level along the shore up to about 490 feet at the southern corner.
  • Rainfall: about 130 inches a year near the middle of the subdivision, per the UH Rainfall Atlas.
  • Lava: HPP sits on the Ailaau (now also called Kualoloa) pahoehoe flow field, which erupted from Kilauea’s summit in the early 1400s, according to USGS.
  • Lava hazard zone: USGS rates HPP as Zone 3.
  • Cesspools: more than 4,000, according to a DOH official quoted in 2015.
  • Water: roof catchment and private wells. A 2015 report put the number of potable wells in HPP at about 250, with no county water system serving the subdivision.

What’s Under an HPP Lot

A Department of Health official summed up HPP in 2015 with two words: “absolutely no soil.” On most lots you scrape away a thin layer of organic material and hit pahoehoe. That rock is fractured, so wastewater moves through it fast, without the filtering a deep soil would give.

State rules (HAR 11-62) deal with this directly. On fractured lava, a leach field has to be a soil replacement system. We break out the pahoehoe, haul it off and place engineered fill so effluent filters through at least three feet of material on its way to groundwater. Your engineer runs the percolation test and a 5-foot soil profile to confirm what you have. Near the coast, separation to groundwater gets tighter.

Breaking and hauling rock is the main reason HPP jobs cost more than jobs on deep soil. Across Hawaii, a typical conversion lands somewhere between $20,000 and $50,000. Bare pahoehoe like HPP’s tends to put a job in the upper half. Our cesspool conversion cost guide breaks down where the money goes.

Typical Projects in a Fast-Growing Subdivision

HPP added more than 1,200 housing units between 2010 and 2020, and a 2012 essay about the subdivision said only about half the land had been developed. So much of the work here is new construction. On Hawaii Island, DOH reviews the wastewater system plans before the county signs off on a building permit, so the septic design has to be settled early. Our page on septic requirements for a new home walks through that order of operations.

The other big group is older homes that went in with cesspools before the statewide ban on new ones in March 2016. Owners usually call us when:

  • They’re pulling a permit for an addition. If the permit raises the bedroom count, DOH can ask for the cesspool to be replaced, and DOH counts a 70-square-foot office or den as a bedroom.
  • The cesspool is being pumped often. More than two pump-outs in 12 months is one of the conditions where DOH may require a conversion.
  • They’re selling. A sale doesn’t trigger conversion under state law, but buyers ask.

With one-acre lots, space is rarely the problem; HPP lots clear the 10,000-square-foot minimum per system easily. Makai lots need to keep the system at least 50 feet from the shoreline.

Getting Equipment Down HPP Roads

HPP roads are private. The Hawaiian Paradise Park Owners Association maintains them with an annual road fee, which is $435 for 2026. Makuu, Paradise, Kaloli and Shower drives are on the association’s June 2026 paved list, along with sections of a couple dozen numbered avenues. Many side roads are gravel.

That matters for us because an excavator on a lowboy trailer, a rock truck and a concrete tank delivery all have to reach your lot. On gravel we plan around wet weather and keep dust in mind. The association runs a fugitive dust complaint line, and in 2012 a DOH dust citation was part of the push to pave more roads.

Wells, Bacteria and Why ATUs Come Up Here

This is the part of the HPP story that no other Puna subdivision shares in quite the same way. In 2014, the University of Hawaii and DOH sampled 32 private drinking water wells in HPP. Half tested positive for total coliform and a quarter for E. coli, a marker of sewage. Detections went up closer to the coast and after heavy rain.

DOH responded by urging HPP residents to put ultraviolet disinfection on their drinking water. The same DOH official said aerobic treatment units (ATUs) may be the only way to stop continued contamination of HPP’s wells. An ATU treats wastewater to a higher level before it reaches the disposal field. It costs more up front and needs a service contract with inspections every six months.

Not every HPP lot needs an ATU, and a conventional tank with a soil replacement field is often approved. But if you or your neighbors have a well, ask your engineer to compare both. DOH’s 2017 report also named a Keaau priority area of about 9,300 cesspools, flagged for potential impact on drinking water. You can check your own parcel on the UH Cesspool Prioritization Tool; our priority area guide shows how.

The 2050 Deadline and Paying for It in HPP

Act 125 gives every HPP cesspool the same hard stop: January 1, 2050. Being in a priority area doesn’t move that date up. On the money side:

  • Very-low-income households may qualify for a USDA Section 504 repair loan (up to $40,000, 1 percent, 20 years). Owners 62 and up can also apply for a grant of up to $10,000. Ask the Hilo USDA office whether you qualify.
  • A state loan program created by Act 204 in 2026 is being set up by the Hawaii Green Infrastructure Authority, with a launch expected late this year.

Near HPP

We also work in Keaau, Orchidland Estates, Ainaloa and Hawaiian Beaches & Shores. For the rest of the district, see our Puna septic services page.

Talk to Us About Your HPP Lot

Tell us your road, your water source (well or catchment) and what you’re planning. We’ll come look at the rock and give you a straight answer on what it will take. Request a free estimate

Frequently Asked Questions

Do I need an aerobic unit in HPP, or will a regular septic tank work?

Many HPP lots can use a conventional tank with a soil replacement leach field. An ATU becomes more likely when there’s a well nearby, when the lot is close to the coast, or when DOH asks for higher treatment. Your engineer makes the call during design.

My HPP property has a private well. Does that change the design?

It can. Your engineer will lay out the system with the well in mind, and DOH reviews the plan. Given the 2014 sampling results, DOH also recommends UV disinfection on HPP drinking water no matter what wastewater system you have.

Why does the excavation take so long on my lot?

Because there’s almost no soil. A soil replacement system means cutting into pahoehoe, hauling the rock out and bringing fill in. That’s the bulk of the time and cost on most HPP jobs.

Is HPP inside a DOH cesspool priority area?

DOH’s 2017 report named a Keaau priority area focused on drinking water. Parcel-level priority is easiest to check on the UH Cesspool Prioritization Tool, which colors each cesspool by priority level.

I’m building on an empty lot in HPP. Can I put in a cesspool to save money?

No. Hawaii stopped allowing new cesspools in March 2016. A new HPP house needs an approved septic system or ATU, reviewed by DOH as part of your building permit.