Hawaiʻi Island cesspool conversion batches, drinking-water areas first

Hawaiʻi Island cesspool conversion: ready to start, drinking-water areas first, a model every island can reuse

Hawaiʻi Island has about 48,600 of the state's roughly 83,000 cesspools, releasing about 29 million gallons of untreated wastewater a day. Conversions there run about 400 a year; at that pace the job takes over a century, and time, not money, is the limit. A UH Hilo dye study at Puakō found sewage from shoreline homes reaching the ocean in as little as 6 hours. This is an updated, more complete version of the Oct 20 idea, “Hawaiʻi Island cesspool conversion batches modeled on Hōnaunau pilot,” and replaces it.

Build on the funded $1 million Hōnaunau pilot with batch conversions of 100 homes in two or three more Hawaiʻi Island communities, chosen by risk and where no County sewer is planned:

• First: cesspools inside well capture zones or near drinking-water wells. The island's cesspools were ranked using 416 government map data layers. About 5,850 sit near drinking water, 95 of them in flood zones too. This protects the aquifers the Council already prioritizes.

• Next: flood-zone and coastal or stream cesspools, where storms and rising seas carry sewage into homes, streams and the ocean.

Candidate areas include South Kona near Hōnaunau, the Puakō area, and a Hawaiian Home Lands homestead off the sewer line such as Panaʻewa. Neighbors upgrade together, so one engineer, one permit package and one crew cover a whole street.

Readiness: licensed local installers and engineers do the work. Installation takes about two weeks per home, and engineering plus Department of Health approval takes up to three months. Homeowner sign-up, site screening and engineering start the day funds are released, so the money is spent within the fiscal year, starting with the sites with the easiest access and approvals.

Results: 100 homes converted. Cost per home, time per home, gallons kept out of drinking water and the ocean, and water-quality changes will be published openly. Prevention costs far less than treating contaminated wells and reefs later.

Relationships: coordinate homeowners, engineers and licensed contractors; reach out to DLNR and DOH so the departments can carry and champion this as a departmental request, and to the Department of Hawaiian Home Lands and homestead associations in the target areas; work with a university research group on monitoring. It uses the state's new Cesspool Conversion Revolving Loan Fund where families qualify, which lowers what the Green Fee covers.

Region: more than half the state's cesspools are on Hawaiʻi Island, many in rural communities and Hawaiian Home Lands homesteads long underinvested in. The model is built to be copied on other islands.

Scale: a fixed goal of 100 homes over FY28–29, with a budget of $7.5 million to $10 million, depending on how much batching lowers the cost per home. Hawaiʻi County estimates $30,000 to $70,000 per conversion. The budget covers coordination, homeowner support, engineering oversight and water-quality monitoring so all 100 homes get done even on hard sites. Money not needed goes back to the Green Fee. The goal is for homeowners to pay nothing up front, and for conversions to become fully government-funded.

Commitment for 20 years or more to help raise Hawaiʻi Island's pace from about 400 conversions a year toward 3,000.

Submitted by ʻĀina Force LLC (Hawaiʻi Island cesspool conversion coordination). Contact: rahul@ainaforce.com, (808) 663-9283.