Individual Wastewater Systems

Individual Wastewater Systems (IWS) are on-site systems for treating and disposing wastewater. Approved IWS treatment equipment are: septic tank, aerobic treatment unit, passive aerobic systems that still require a septic tank (i.e., Eljen, Presby), bioreactor garden (i.e., Ridge to Reefs), composting toilets and incinerator toilets. Composting toilets and incinerator toilets only treat toilet waste, shower and kitchen wastewater still requires treatment and disposal.

Engineer Resources

To file for an Individual Wastewater System (IWS) online, please go to: .

Additional Information


Homeowner Resources

How do I upgrade my existing cesspool or replace my failing cesspool or septic system?

1st step: Hire a Hawaii licensed civil engineer to help you develop a plan for a new individual wastewater system (IWS).   An IWS is either a septic or aerobic treatment unit system.  You can check if an engineer is a licensed civil engineer by using the Department of Commerce and Consumer Affairs’s (DCCA) Professional Vocational Licensing Search Tool to find the engineer’s record, check the License Class, and then the License’s status.

Alternatively, we also have a list of licensed civil engineers that prepare IWS plans in the State of Hawaii is provided below:

  • List of Licensed Civil Engineers that prepare IWS plans | pdf |

2nd step: Your licensed engineer will submit plans to the Wastewater Branch for review and approval.  Plans may be submitted online by your engineer to . Below are a list items that need to be submitted with the IWS plans.

  • Application Form
  • Owner’s Certification Form
  • Site Evaluation Form

3rd step: After plans are approved by the Wastewater Branch, you must hire a licensed contractor holding an A, C-9, C-37, C-37a or C-43 license. You can also check this by using the DCCA’s Professional Vocational Licensing Search Tool to find the contractor’s record, check the License Class, and then the License’s status. Hiring a contractor holding a license other than what is required will not be accepted by the Wastewater Branch.

4th step:  Your licensed civil engineer should be monitoring the construction of the IWS.  At the end of construction, your engineer is required to submit a final construction inspection report with a completed contractor certification form to the Wastewater Branch.

  • IWS Construction Inspection Report
  • Contractor Certification Form

5th step: Your licensed engineer submits the completed IWS Construction Inspection Report with Contractor Certification Form to the Wastewater Branch.  The Wastewater Branch will issue an approval to use letter to your engineer if there are no discrepancies with the IWS Construction Inspection Report and Contractor Certification Form.  The Wastewater Branch will not be able to issue you a final approval to use of your new IWS unless these two forms are submitted by your licensed engineer.   Your new IWS will be in non-compliance if the Wastewater Branch does not issue an approval to use of your system.

Should you have questions, please email your questions to [email protected] or contact one of our offices.  If you are a licensed civil engineer and would like to be added to our list, please email us your information or call the Oahu office.