If your Maui home sits on a cesspool, a big excavation job is in your future. State law requires every cesspool in Hawaiʻi to be upgraded, converted or connected to sewer, and Maui, especially Upcountry, has thousands of them.
The law: Act 125
In 2017 the Legislature passed Act 125, which requires all cesspools in the state to be upgraded to a septic system or aerobic treatment unit, or connected to a sewer, by 2050. In 2018, Act 132 created a Cesspool Conversion Working Group inside the Department of Health to build a long-range statewide conversion plan.
The state later sorted cesspools into priority 1, 2 and 3 levels using the University of Hawaiʻi's 2021 cesspool hazard assessment tool. Priority 1 cesspools pose the highest risk to drinking water, streams and reefs.
How many cesspools are on Maui?
Reporting from Maui Now puts the island's count at more than 12,000 cesspools, with about 7,400 of those Upcountry. Upcountry is a priority area because the Health Department linked nitrate contamination in groundwater there to sewage.
Is the 2050 deadline changing?
Possibly, and it's worth watching. Several 2026 bills proposed extending deadlines or staggering them by priority level. One proposal (SB 2243) would have set different end dates for priority 1, 2 and 3 cesspools, and it failed. Another (HB 1985) aimed to allow certain extensions and to have the Health Department focus on the highest-risk cesspools first. Until the law changes, plan around 2050. If you might sell sooner, expect buyers to ask what wastewater system the home has.
What the conversion actually involves
- Design: a licensed engineer evaluates soil and slope and designs a septic or aerobic system sized for the home.
- Health Department approval: the plans go to the state Department of Health's wastewater program.
- Excavation: the old cesspool is pumped and properly closed. A tank is set and a leach field or absorption bed is dug. On rocky Upcountry ground this is where cost and time swing the most.
- Inspection and backfill.
Look for contractors with excavation and septic experience. Hawaiʻi has specialty license classes for both, C-17 for excavating, grading and trenching and C-9 for cesspools. See how to check a license.
What does it cost?
The Cesspool Conversion Working Group's study estimated conversion construction costs from about $10,000 to $38,000, before Maui's realities such as rock, slope, access and long haul distances. Get at least three quotes and ask each contractor what happens if they hit rock.
The Kula fire rebuild showed how big a factor this is. Maui Now reported that costly wastewater upgrades slowed rebuilding Upcountry, while some Lahaina properties were allowed to keep structurally sound cesspools under Health Department guidance.
Find a contractor
Browse our septic and cesspool contractors, or see everyone in Upcountry. Landlords with older rentals can also ask Maui Property Managements about planning upgrades between tenants.
Sources
- Hawaiʻi Legislature: SB 2243 (2026) findings on Act 125
- Hawaiʻi Legislature: Act 132 (2018) Cesspool Conversion Working Group
- Maui Now: Kula fire rebuild runs into costly wastewater upgrades
- Big Island Now: Working group cost range for conversion
- Digital Democracy: SB 2243 status
- Digital Democracy: HB 1985