What Act 125 actually says
Act 125, signed into Hawaiʻi law in 2017, 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. There is no grandfather clause for residential property.
The Hawaiʻi Department of Health (DOH) Wastewater Branch is the agency that enforces Act 125, issues IWS permits, and maintains the cesspool priority ranking that determines whether your property faces the 2030, 2035, or 2050 deadline.
The 2030 priority tier (Priority 1)
Priority 1 cesspools are those DOH has identified as the highest risk to public health and the environment. The 2030 tier captures cesspools within 200 feet of a shoreline, perennial stream, wetland, or drinking-water source — meaning much of coastal Kauaʻi, the entire Hanalei Bay watershed, the Wailua River corridor, and any parcel near a drinking-water well falls under this earliest deadline.
If you own property on the North Shore, near Wailua, near Nāwiliwili, or anywhere along the south-shore coast, assume Priority 1 until DOH says otherwise.
The 2035 priority tier (Priority 2)
Priority 2 captures cesspools in environmentally sensitive areas just outside the Priority 1 buffer — typically high-density residential zones, areas with known groundwater contamination, and parcels in the broader watershed of impaired surface waters. Much of Kapaʻa, Līhuʻe, and Kōloa fall in this tier.
The 2050 statutory deadline (Priority 3)
Every cesspool not already retired under Priority 1 or 2 must be upgraded by January 1, 2050. This is the statutory backstop — the latest legal date a cesspool can be in service in the State of Hawaiʻi.
How to find out which tier your property is in
DOH publishes the cesspool priority map; your TMK and a quick site visit answer the tier question. We do this assessment for free as part of any Kauaʻi cesspool conversion consultation — call (808) 855-3478 and we'll tell you which deadline you're working against.
What happens if you miss your deadline
Operating an illegal cesspool after the deadline carries DOH enforcement risk and, more practically, kills any future property sale — title companies and lenders are increasingly flagging non-compliant cesspools at closing. Several Kauaʻi sales in 2025 stalled at the cesspool disclosure step.
The cheapest cesspool conversion is the one done two years before the deadline, not two months after a sale falls through. Permit queues at DOH are already lengthening as 2030 approaches.
Read the full Kauaʻi cesspool conversion guide
Our pillar page on Kauaʻi cesspool conversion & Act 125 compliance covers the four IWS options under Hawaiʻi DOH, the permit process timeline, full cost ranges, and the financing landscape in detail.
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