Cesspool Conversion Guide
Technical Assistance for the Cesspool Conversion Process
This page aims to provide a step-by-step guide for homeowners in Hawaiʻi looking to convert their cesspools or install an Individual Wastewater System (IWS).
It covers the approval process, from hiring a licensed civil engineer to final compliance with the Hawaiʻi Wastewater Branch. You'll find key information on system options, site evaluations, wastewater treatment methods, and contractor requirements.
Additionally, the page offers resources on assessing wastewater capacity, environmental considerations, and connecting to existing sewer lines. Whether you're starting the process or exploring your options, this guide will help you navigate wastewater system installation and compliance in Hawaiʻi.
Are you a Hawaiʻi homeowner looking to convert a cesspool? Here are the steps to obtain approval for an Individual Wastewater System (IWS) in Hawaiʻi
Hire a Hawaiʻi-licensed Civil Engineer
Submit Plans for DOH WWB Review
Hire a Licensed Contractor
Construction Oversight and Final Report
Final Submission and System Approval
What is the best individual wastewater system for your property?
Upgrading a cesspool or replacing a failing septic system involves installing an Onsite Wastewater Treatment and Disposal System (OWTS), also known as an Individual Wastewater Treatment System (IWS). The IWS typically utilizes a septic or aerobic treatment unit. Below is a summary of the steps recommended by the Department of Health Wastewater Branch (DOH WWB). Refer to the DOH website for the most up-to-date requirements.
Step One (Hire a Hawaiʻi-licensed Civil Engineer)
Hire a Hawaiʻi licensed civil engineer to help develop a plan for a new onsite wastewater treatment system. Licensed engineers can be found using the Department of Commerce and Consumer Affairs (DCCA) Professional Licensing Search Tool or the HDOH’s approved engineer list.
Step Two (Submit Plans for DOH WWB Review)
The licensed engineer submits the plans to the Department of Health Wastewater Branch (DOH WWB) for official review and approval. This submission includes the application form, the owner certification form, and the site evaluation form. Common types of approved IWS include septic systems and aerobic treatment units. Other alternative systems may be approved such as passive aerobic systems such as bioreactor gardens, composting and incinerator toilets.
Step Three (Hire a Licensed Contractor)
After the DOH WWB approves your plans, you must hire a licensed contractor who holds one of the following specific licenses: A, C-9, C-37, C-37a, or C-43. The Department of Health Wastewater Branch (DOH WWB) will not accept work performed by a contractor with any other license. You can verify the contractor's License Class and current status using the DCCA's Professional Vocational Licensing Search Tool on the DOH website.
Step Four (Construction Oversight and Final Report)
The licensed civil engineer should be monitoring the OWTS construction. Once complete, the engineer should submit the Final Construction Inspection Report and the completed Contractor Certification Form to the Wastewater Branch.
Step Five (Final Submission and System Approval)
The licensed engineer should submit the completed Construction Inspection Report and Contractor Certification Form to the DOH WWB. If these documents have no discrepancies, the Wastewater Branch will issue an Approval to Use letter. Without this final approval, the new IWS/OWTS will be in non-compliance.
Should you have questions with this process, please email your questions to doh.wwb@doh.hawaii.gov or info@waicleanwater.org.
Things to Consider in Converting
What Can a Cesspool Be Converted To? While IWS’s consisting of a septic tank and a leach field are common, they may not be the best option available depending on your location and conditions. More advanced systems can treat waste more effectively and reduce pollution. Learn more at the US Environmental Protection Agency: Types of Septic Systems. For further information, visit What to Expect in Designing your Wastewater Treatment System and NOWRA’s Onsite Wastewater Treatment System.
Assess Household Wastewater Capacity - A cesspool serving the equivalent of more than five (5) bedrooms is considered a Large-Capacity Cesspool (LCC) with more rules. More info at US Environmental Protection Agency: Large-Capacity Cesspools
Proximity to the Ocean - If your home is within 1,000 feet of drinking water well, 50 feet from the ocean, converting your cesspool is essential to protect groundwater and marine ecosystems from pollution. Therefore it may require higher treatment standards as well to ensure leaching into these environments. Consult with your licensed engineer to determine the best options for your property.
Availability to Connect to Existing Sewer - To determine if your Hawaiʻi property can connect to existing sewer lines, contact your county’s Wastewater Division for sewer maps and service area details. A licensed civil engineer can assess feasibility, including distance, elevation, and infrastructure needs. If eligible, you’ll need a sewer connection permit, and a contractor will handle installation. The county will inspect the connection before granting final approval. Check with Honolulu, Maui, Hawaiʻi, or Kauaʻi Wastewater Divisions for specific requirements.
Financing Options for Homeowners Converting Cesspools - Check out our financial resources and see if you are eligible for any funding opportunities to support your cesspool conversion.
What are cesspools, and why do they need to be converted?
A cesspool is a hole in the ground receiving untreated wastewater. Cesspools pollute the environment and endanger public health.
More info at Hawaii Department of Health: Cesspools in Hawaii
Are all cesspools equally harmful as each other?
Not all cesspools are equally harmful as they can vary in size and the volume of waste they handle. Additionally, the location of the cesspool, the type of waste that is disposed of, and the surrounding soil conditions can also affect the level of harm.
A cesspool that is located near a water source or in an area with high water table could be more harmful than one that is located farther away or in an area with a lower water table.
Graphic by Michael Mezzacapo
Department of Health’s List of Priority Areas
Map of Cesspool Locations in Hawaiʻi
Click on the map to see an interactive map based on a number of studies by University of Hawaiʻi and the Department of Health. You can enter any address into the search bar to move the map there. If there is an orange dot at the location you entered, this property is likely served by a cesspool. If the map area is shaded in blue, it is located in one of the cesspool upgrade priority areas as defined by the Hawaiʻi Department of Health. The priority areas will be updated soon. Research is ongoing to better identify properties that are most likely served by cesspools.
Note: Cesspool locations and priority areas are subject to change. Hawaiʻi lacks a complete map of all cesspool locations.