Hawai'i State News

Working Group: Most contaminating Hawaiʻi cesspools should be converted by 2030

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Hawaiʻi Island has the most cesspools of the four counties with 48,596. It also has the most Priority Level 1, with 5,119 marked in red. Orange is Priority Level 2 and yellow is Priority Level 3. Map Source: Hawaiʻi Cesspool Prioritization Tool

In an effort to reduce the 53 million gallons of untreated sewage contaminating the State of Hawaiʻiʻs groundwater and surface waters each day, the Cesspool Conversion Working Group advised moving up the deadline for converting the worst offenders by 20 years, to 2030.

The group — which has been working on the issue for four years — presented its findings on Wednesday to the state House Committee on Energy & Environmental Protection and the Senate Committee on Agriculture & Environment in a joint virtual informational briefing.

“We wanted to thank you for all your hard work on this crappy issue,” Senate Committee Chair Mike Gabbard said before the presentation began.

In 2017, the the State Legislature passed Act 125, requiring that all cesspools be converted by 2050. In 2018, to address the significant challenges raised by this conversion requirement, Act 132 established the Cesspool Conversion Working Group, tasked with further studying this issue and developing a long-range, comprehensive plan for the conversion of all cesspools in the next three decades.

The working group recently finalized its report, which also included what conversion options are available and how best to provide financial assistance to homeowners unable to afford the pricey conversions.


The counties of Maui, Honolulu, Kauaʻi and Hawaiʻi have 88,000 cesspools, which are a pit lined with cement or stone that lacks the ability to filter waste, eventually contaminating the surrounding soil.

Dr. Christopher Shuler with the University of Hawaiʻi at Mānoa, told the committee there’s not the capacity (workers, funding and materials) to replace the cesspools all at once, so the committee identified the locations of the cesspools and ranked them by their chances of causing harm to people and the environment.

Priority Level 1 cesspools had the greatest contamination hazard, followed by Priority Level 2 (significant contamination hazard) and Priority Level 3 (pronounced contamination hazard).

To see where the cesspools are located and their ranking, click here. For the Hawaiʻi Cesspool Prioritization Tool, click here. You can scroll on the site to find all the islands.

Cesspools near coastal areas are considered more hazardous because the untreated sewage can reach the ocean and affect the reefs. But inland cesspools can affect groundwater, which also presents major concerns.


Hawaiʻi Island has the most cesspools of the four counties with 48,596. It also has the most cesspools in the state ranked as Priority Level 1 with 5,119, which is 37% of the state’s Priority Level 1 cesspools.

Hawaiʻi Island has 2,619 cesspools at Priority Level 2 and 40,858 at Priority Level 3.

According to the study, Hawaiʻi County residents also have the least access to centralized sewers at 71%.

And, to make matters worse, the report found that Hawaiʻi Island homeowners also will be the most financailly affected in the state. On average, cesspool upgrades would exceed 2% of a Hawaiʻi county residentʻs income after a potential $10,000 rebate that the state could secure through grants and other means.

Ted Bohlen, a member of the Cesspool Conversion Working Group, told the joint committee the state will need a lot of additional help to administer the work to get the cesspool upgrades done. Staff will need to be hired; contractors will need to be identified; and grants will need to be procured to make the conversion more affordable for homeowners.


Finding enough contractors likely will be a big challenge with a limited number of skilled workers, including plumbers, needed to do the conversion work.

According to the study, the cesspool conversion construction cost could range from $10,000 to $38,000. While the most common conversion is a septic tank to connect to an existing or new public sewer, working group members said there needs to be a variety of sewage conversion and funding options.

“There isn’t a one size fits all solution,” one group member said. “Homeowners need incentives to make the conversion; and we need sustainable public outreach.”

Bohlen said the bottom line is the state needs to move forward with a plan to aggressively convert the problematic cesspools and hopes the Legislature will address this to lessen the burden to homeowners.

The 2022 report of the working group is available here.

Editorʻs note: This story was updated with a more accurate map of the cesspool priorities.

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