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Hawai‘i Cesspool Prioritization Tool 


The Hawai‘i Cesspool Prioritization Tool (HCPT) is a map-based tool that displays the prioritization level for each of Hawai‘i’s 83,000+ cesspools. Per Act 125 Session Laws of Hawai‘i (2017), all cesspool owners are required to upgrade, convert, or connect to sewer before 2050. While all cesspools degrade water quality, some have particularly acute and hazardous impacts on human and ecosystem health because of their geographic location.

Based on the best available statewide data and expert input, cesspools across the islands have been classified in three categories of priority for their conversion. Each cesspool’s priority ranking represents the urgency of their replacement prior to 2050.

How to Use the HCPT

  1. Click the blue button above to launch the tool.
  2. Read and accept the terms and conditions. 
  3. Review the ‘i’ information button at the top right side of the screen for introductory information about the site.
  4. Use the + and – buttons at the top left of your screen to zoom in or out, or use the search bar to input a place name, address, or tax map key. 
  5. If your area of interest is shaded in red, orange, or yellow, the zone has been deemed a priority for conversion by the DOH. 
  6. To customize your view, use the buttons at the bottom left of your screen. The leftmost button (four stacked squares) allows you to customize your basemap. The middle button (ruler) provides measuring tools. The rightmost button (download) provides options to create a report for your area, upload shapefiles, and create buffers. 

What are the Priority Areas?

Screenshot-Hawai‘i Cesspool Prioritization Tool

The HCPT prioritization method places each geographic area into three prioritization categories:

Priority Level 1: These cesspools have the greatest potential to impact human health and the environment and are directly adjacent to sensitive natural resources like coral reefs or drinking water aquifers (map color red).

Priority Level 2: These cesspools rank behind Priority 1, but still pose a significant hazard to human health and the environment. Priority 2 cesspools may be close to sensitive natural resources like steams or drinking water aquifers (map color orange).

Priority Level 3: These cesspools still have an impact on human health and the environment but may be further away from sensitive natural resources or areas that may directly impact human health (map color yellow).

Hawai‘i Cesspool Prioritization Tool: Input Data

The HCPT’s Priority Areas were determined through a data-driven process. Fifteen statewide data layers with relevance to cesspool hazards were overlain with cesspool locations in a code-based geospatial tool. With expert input, these risk factors were weighed according to the significance of their environmental and human health impacts. These risk factors can be explored in the HCPT companion tool, the ‘Input Data App‘.

The tool creation process and methodology is detailed in the report, ‘Hawai‘i Cesspool Hazard Assessment & Prioritization Tool: Updated Report & Technical Appendices’ (2022). For a deeper dive into the 15 risk-factors, explore the Storymap, ‘Understanding the Priority Areas’ and view the video below, ‘How were the HCPT Priority Areas Determined?’.

Explore Further

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Cesspool Conversion Working Group

Report to the Legislature 2022 Regular Session

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Potty Portal

Wastewater Alternatives & Innovations (WAI)


For more information on the HCPT and Input Data App, contact Christopher Shuler,

To discuss educational opportunities and outreach products, contact Melanie Lander,