Act 125 (Cesspool Conversion)
Act 125, enacted in 2017, requires that every cesspool in Hawaiʻi be upgraded, converted to a septic or aerobic system, or connected to a sewer line by the year 2050. The state has roughly 83,000 cesspools, and the mandate applies statewide.
Cesspools discharge untreated wastewater into the ground, and Hawaiʻi has more of them than almost any state. Act 125 set the 2050 deadline for eliminating them; the Department of Health has since worked to prioritize conversions, with the highest priority given to cesspools near drinking-water sources, streams, and the shoreline.
A cesspool conversion is a ground-disturbing project. Depending on the site, a replacement can require an aerobic treatment unit rather than a conventional septic system, deeper excavation, and additional design where the parcel sits in a groundwater-protection zone — all of which affect cost, footprint, and permitting.
A documented cesspool on a parcel is a known future cost and a ground-disturbing project on the horizon. For due diligence, it's worth surfacing whether a parcel has a cesspool on record and what a compliant conversion would involve — before the deadline forces the timing.
By 2050, under Act 125 (2017). All cesspools statewide must be upgraded, converted to septic/aerobic systems, or connected to sewer by that deadline.
Roughly 83,000 statewide — among the highest counts of any U.S. state — which is why Act 125 set a firm conversion deadline.
This is a plain-language reference, not legal advice. KILO is a pre-development screening tool, not a system of record — confirm any determination with the agency of jurisdiction.