What Act 125 actually says
Act 125, signed into Hawaiʻi law in 2017 and codified at HRS 342D-72, makes it illegal to operate a cesspool past January 1, 2050. Every cesspool on every island must be upgraded to an approved Individual Wastewater System (IWS), converted to septic, or connected to municipal sewer before that date.
January 1, 2050 is the only enacted statewide cesspool deadline. The Hawaiʻi Department of Health (DOH) Wastewater Branch is the agency that administers Act 125 and issues IWS permits.
Priority 1: plan first (planning urgency, not a legal date)
DOH publishes a Cesspool Hazard Assessment & Prioritization Tool that groups cesspools by risk to public health and the environment. Priority 1 identifies systems generally closer to shorelines, perennial streams, wetlands, or drinking-water sources, which include much of coastal Kauaʻi.
Priority 1 is a planning-urgency category to help homeowners and agencies decide where to convert first. It is not a legal deadline or a mandate to convert by any date other than the statewide January 1, 2050 deadline.
Priority 2: plan early (planning urgency, not a legal date)
Priority 2 groups systems in environmentally sensitive areas just outside the Priority 1 buffer, and in high-density residential zones where groundwater impacts are more likely.
Priority 2 is also a planning-urgency category. It is not a legal deadline. The only enacted statewide deadline is January 1, 2050.
The 2050 statewide deadline
Hawaiʻi's statewide cesspool deadline is 2050 under HRS 342D-72. Priority 1 through Priority 4 are planning tiers used by the Department of Health to sequence the work. They are not separate legal deadlines. HRS 342D-72(b) also carries an exemption, so the 2050 date is not absolute for every property.
How to find your property's priority category
The Hawaiʻi Cesspool Hazard Assessment & Prioritization Tool is the authoritative source. Look up your parcel there, or contact the Hawaiʻi DOH Wastewater Branch. We do not infer property priority from geography.
We can walk your property, check the DOH tool with you, and outline your options. Call (808) 855-3478 to schedule.
What happens if you wait
Operating a cesspool past January 1, 2050 will be prohibited under state law. Well before then, title companies, lenders, and insurers are already asking about wastewater system type on sales, refinances, and renewals. Several Kauaʻi sales in 2025 stalled at the cesspool disclosure step.
The cheapest cesspool conversion is the one planned years in advance rather than months before a sale.
Read the full Kauaʻi cesspool conversion guide
Our pillar page on Kauaʻi cesspool conversion and Act 125 compliance covers the four IWS options under Hawaiʻi DOH, the permit process timeline, and the financing landscape in detail.
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