Every cesspool in Hawaii has the same deadline, but they don’t all pose the same risk. A cesspool a few hundred feet from a reef or a drinking water well is a bigger problem than one on a large inland lot. To sort that out, the state ranks cesspools by priority, and you can look up your own property in a couple of minutes.
Here’s how the ranking works, how to check your home, and what your result actually means.
Where the priority levels come from
The University of Hawaii Sea Grant College Program built the Hawaii Cesspool Prioritization Tool with the Department of Health (DOH). It first came out in 2021 and has been updated since, most recently with a 2024 report.
The tool scores every cesspool in the state using 15 layers of statewide data, weighted by expert input. The basic question is how likely a cesspool is to hurt people or the environment. Closeness to coral reefs, drinking water aquifers and streams is a big part of the picture.
You might also run into an older map. In 2017, DOH named 14 priority areas in a report to the legislature: Upcountry Maui; Kahaluu, Diamond Head, Waimanalo, Waialua and Ewa on Oahu; Kapoho, Keaau, Puako, Hilo Bay and the Kailua-Kona coast on Hawaii Island; and Kapaa/Wailua, Poipu/Koloa and Hanalei Bay on Kauai. That list was a first pass. The UH tool goes cesspool by cesspool and is the one that matters now.
What each level means
The tool sorts cesspools into three colors.
- Priority 1 (red): the highest risk to people and the environment. These cesspools sit right next to sensitive resources like coral reefs or drinking water aquifers.
- Priority 2 (orange): still a significant hazard. Often near streams or drinking water aquifers.
- Priority 3 (yellow): a real impact, but usually farther from the most sensitive places.
The 2021 analysis counted about 13,900 Priority 1 cesspools, 13,500 Priority 2, and 54,000 Priority 3 across the state. Hawaii Island has the most Priority 1 cesspools, about 37%, followed by Oahu at 35%, Kauai at 21% and Maui at 7%.
On Oahu, Priority 1 cesspools are concentrated along the coast. Large stretches of the Windward side, including Kahaluu and the rural shoreline from Hauula to Kahuku, fall into the top tier. So does most of the North Shore from Sunset Beach to Haleiwa, along with pockets in Kailua, Waimanalo, Ewa Beach, Makaha, Mokuleia and Waialua.
How to look up your property
- Go to the Hawaii Cesspool Prioritization Tool page and click the button to launch the map.
- Read and accept the terms.
- Type your street address, a place name, or your tax map key (TMK) into the search bar. You can also zoom in with the plus and minus buttons in the top left.
- Look at the color of the dot or area over your property. Red, orange or yellow means DOH considers it a conversion priority.
- If you want more detail, the “i” button in the top right explains the map, and the tools in the bottom left let you change the base map or create a report.
Your TMK is on your property tax bill or your county’s real property website. It’s the most reliable way to land on the right lot, especially in rural subdivisions where street addresses can be hit or miss.
The newest version of the tool also includes a layer showing areas where sewer expansion is planned. If you’re in one of those areas, connecting to the sewer may eventually be an option instead of an on-site system.
What your priority level does and doesn’t change
This is where a lot of people get confused.
It doesn’t change your deadline
Under current law, every cesspool has until January 1, 2050, no matter its priority. Bills to give Priority 1 and 2 cesspools earlier deadlines have been introduced, including one in 2026 that would have set 2035 for Priority 1, but none have passed. Our guide to Act 125 covers the full history.
It can affect your access to money
Some funding programs use priority levels to decide who gets help first. The DOH pilot grant only funded Priority 1 and 2 cesspools. Kauai’s current grant ranks applicants higher if they’re in a Level 1 or 2 area. If you’re red or orange on the map, future programs may well put you near the front of the line too. See our funding guide for what’s open now.
It may affect the system you need
Higher-priority cesspools tend to be in sensitive places, like near the shoreline or above drinking water. Those spots often come with shallow groundwater and tight setbacks, which can rule out a basic tank and leach field and point the engineer toward a treatment unit or raised mound. That can raise the cost, which our cost guide explains.
It’s a strong hint about what comes next
If the legislature does set earlier deadlines someday, the proposals so far have all started with Priority 1. A red result is a good reason to start planning now rather than later.
Keep the results in perspective
The tool is built from the best statewide data available, not from a visit to your yard. It’s a good starting point, but it can’t see your actual soil, how deep the groundwater is, or exactly where the cesspool sits on the lot. A site evaluation fills in those gaps and tells you which systems will actually work.
If your property shows up as Priority 1 or 2 and you’d like to know your options, we can take a look. Request a free estimate.
Frequently Asked Questions
How do I find out if my cesspool is Priority 1?
Search your address or TMK in the University of Hawaii’s Hawaii Cesspool Prioritization Tool. Red means Priority 1, orange means Priority 2, and yellow means Priority 3.
Does Priority 1 mean I have to convert sooner?
Not under current law. Every cesspool has until January 1, 2050. Priority 1 cesspools are first in line for some grants, and they’ve been the first target of bills proposing earlier deadlines.
Why is my area a priority when my cesspool works fine?
Priority isn’t about whether your cesspool is working. It’s about where the untreated wastewater ends up. A working cesspool near a reef or drinking water well still sends raw sewage into the ground right next to it.
Which island has the most Priority 1 cesspools?
Hawaii Island, with about 37% of the state’s Priority 1 cesspools. Oahu is close behind at about 35%.
What’s the difference between the 2017 priority areas and the new map?
The 2017 DOH report named 14 broad areas across the state. The University of Hawaii tool, released in 2021 and updated since, scores each cesspool individually and is the more detailed, current source.
What if the map is wrong about my property?
The map relies on statewide data, so it can miss details about a specific lot. If your cesspool’s location or condition is different from what the map assumes, a site evaluation and DOH will make the final call on what your property needs.
Is my septic tank on the map?
The tool tracks cesspools. If your home already has a permitted septic system or treatment unit, you’ve already converted and Act 125 doesn’t apply to you.
