This webpage is intended for informational purposes only and is designed to provide important introductory information for homeowners and realtors. FOR ADDITIONAL HELP REGARDING YOUR SPECIFIC SYSTEM, PLEASE HIRE A LICENSED WASTEWATER ENGINEER.

Wastewater Systems in Hawaii

When learning about wastewater systems in Hawaii, it’s important to understand that there are many different types of wastewater systems that exist and they all treat the wastewater to varying degrees.

• Cesspools: A cesspool is one of the oldest and most harmful types of wastewater disposal that discharges untreated wastewater from human waste directly to Hawaii’s groundwater. It can lead to contamination of groundwater, drinking water sources, streams, beaches, and oceans with disease-causing pathogens and other harmful substances. For additional information:
  • DOH: Cesspools in Hawaii
  • EPA: Cesspools in Hawaii
• Large Capacity Cesspool (LCC): A cesspool that serves:
  • Multiple residential dwellings, or single family residential dwellings and structures that produce wastewater.
  • Non-residential buildings that have the capacity to serve twenty or more persons per day.
  • Single family residential dwelling that is also used for business activities (e.g., beauty salon, childcare center, pet grooming, etc.).

  For more information on LCC, please visit: EPA: Large-Capacity Cesspools.

• Individual Wastewater System (IWS): Typically required for single family homes with flow rates less than 1000 gallons per day. IWS are typically composed of a septic tank unit and an absorption system. A septic tank performs primary treatment of wastewater, which uses anaerobic (no air added) digestion and settling to remove some organic matter and solids. An absorption system is usually a distributed network of perforated pipes that is more than 18 inches underground. It is usually fragile, so heavy objects (e.g., garden sheds, cement slabs) or tree roots can easily damage it. However, they can be placed under driveways or parking lots if properly designed for it. Though uncommon, some residences may require an aerobic treatment unit (higher quality of wastewater treatment) instead of a septic tank unit due to location or other geographical features. To determine what wastewater system is right for your property, please hire a wastewater engineer.
• Wastewater Treatment Works: Also known as Wastewater Treatment Plants (WWTP), they are typically required for wastewater flow rates that are greater than 1000 gallons per day. They are typically used for everything from large houses to regional wastewater facilities, like City and County of Honolulu’s Sand Island Wastewater Treatment Plant. Wastewater Treatment Works typically perform at least secondary treatment of wastewater, which uses aerobic (air added using a pump) digestion to reduce the amount of organic matter and pathogens in the water, and denitrification to prevent eutrophication. Higher levels of wastewater treatment are possible to achieve water known as recycled water that can be used for a variety of environmentally beneficial applications, including but not limited to irrigation. The counties’ or private company’s sewer system, which many people are connected to, collects the wastewater from its sewer system to a regional wastewater treatment works for treatment and disposal.

Although it has been the State of Hawaii’s goal to move towards more regional sewage collection to reduce the cost to homeowners and protect Hawaii’s environment, Hawaii still has many cesspools, IWS, and small Wastewater Treatment Works that are built and located on the property they service. It is important to exercise appropriate caution when owning, selling, or buying a property in Hawaii to ensure that the type of wastewater system is accurately identified, and that the wastewater system is managed and operated correctly, safely, and according to all state laws.

Since wastewater systems are below ground and out of sight, they are often times neglected when inspecting a property or misunderstood when detailing them on reports. For example, people will often refer to cesspools as “septic systems” or that the property is “sewered” when they have an IWS. The recurring maintenance costs and legal requirements for each wastewater system is very different, and every homeowner and realtor should be aware of them. For example:

• Cesspools and septic tanks must be regularly pumped by a registered pumper and hauler to prevent overflows and backed up wastewater.
• Components of aerobic treatment units or wastewater treatment works will typically need to be replaced every 10 to 20 years, unless otherwise stated by the manufacturers specifications.
• IWS should be inspected about every 5 years to ensure continued operation.
• Aerobic treatment units require a certified operator to perform operation and maintenance on it and have an active service contract.
• Wastewater treatment works require a certified operator to perform operation and maintenance on, at least, a weekly basis and submit data to the Department of Health.
• Before January 1, 2050, every cesspool in the State must be upgraded to an IWS or connected to a sewer system. For additional information and exemptions see section HRS 342D-72.
• Any homeowner who is found to be in violation of HRS chapter 342D, Water Pollution can be fined up to $60,000 for each separate offense and each day of each violation shall constitute a separate offense.

FAQ

Why is it that the wastewater branch has not notified me of the status of my application?

It is the responsibility of the licensed engineer that was hired by the homeowner to keep the homeowner informed on the progress of the project and of tasks that need to be completed to address our reviewers comments. The wastewater branch primarily communicates with only the engineer to expedite the review process and prevent conflicting information from slowing down applications. Additionally, the majority of work needed to address reviewer comments can only be completed and submitted by a licensed engineer. The wastewater branch does not mediate disputes between homeowners and the engineers or contractors they hire.

For additional information about the review process see our step-by-step guide for homeowners learning about the IWS installation process.

How do I know what wastewater system I have or if I am connected to a sewer system?

It is always best to hire a licensed wastewater engineer, certified operator, or licensed plumber to inspect your wastewater system, but you can take some simple steps to narrow down the potential options. You can find these simple steps on our guide titled, “What sort of wastewater system do I have?”. Additionally, you can request records from the wastewater branch to see if we have any information on your property’s wastewater system by following the instructions at: Record Request.

What do I do if I can’t find my wastewater system and the wastewater branch has no records of it?

At this point, we would recommend hiring an licensed wastewater engineer, certified operator, or licensed plumber to inspect your wastewater system. You can check to see if someone has a license by using DCCA’s License Search Tool or check if an operator is certified by calling our Oahu office. In the event that there is a cesspool, the Department of Health Wastewater Branch will require that a cesspool card/existing cesspool information card be filled out by the licensed engineer. A blank version of the card can be found on our IWS page.

What is the price of upgrading a cesspool by installing a new IWS/septic tank/aerobic treatment unit?

The price can vary based on the property’s location and geographical qualities, and other market conditions. The price can be broken down into the following categories: engineering costs (i.e., design, drafting, administrative, etc.), materials cost, and construction costs (i.e., labor, time, etc.). Typically, the majority of the price to the homeowner will consist of the cost of materials and construction, while the remainder will be the engineering cost. Please contact a wastewater engineer and wastewater contractor for accurate quotes of current prices.

How do I know when future financial support programs for cesspool upgrades will be available?

We have a dedicated page for financial support programs: “Financial Support Programs for Cesspool Conversion”. This will be the first place we upload new information regarding future programs and it contains details on past programs so you can get an idea of what to expect.

Where do I start when it comes to installing an IWS?

We have step-by-step guidance for homeowners wanting to install a new IWS: Individual Wastewater Systems: Homeowner Resources.

I heard that the 2050 deadline for cesspool conversion may be moved forward? What’s that about?

In Hawaii’s 2025 Legislative Session, senate bill SB 542 was introduced that would require properties, with cesspools that pose a greater risk to public health and the environment, be upgraded to an IWS as soon as 2035. This bill was not passed, and the 2050 deadline pursuant to section HRS 342D-72 is still in effect.

How do I check on the status of a building permit application?

Please contact your local county building department for the status of your building permit application.

How do I check on the status of an application for a new IWS?

Feel free to call your local wastewater branch office for assistance on this. Please have the Tax Map Key (TMK) of the property in question ready so that we can look up the records and the island on which the property is located. If you need help figuring out your TMK, please use our guide entitled: “What is my Tax Map Key (TMK) number?”. Please be respectful of the engineer’s time when calling and be mindful of the following:

• The more time our engineers take answering phone calls about reviews, the less time they have to perform the reviews.
• All reviews are on a first come, first serve basis. We do not expedite reviews by allowing applicants to “cut in line”.
• Our reviewers will often times provide comments that need to be addressed by engineers submitting plans. These comments cannot be addressed by the homeowner and must be addressed by the hired licensed engineer.
• It is the responsibility of the hired licensed engineer to keep the homeowner informed of the progress of the project and of things that need to be completed to address our reviewers comments.
• Homeowners calling reviewers and trying to resolve engineering comments will not accomplish anything other than slowing our pace of reviews because their hired licensed engineer must address the comments.

How long does it take to receive an approval of an IWS?

We only have, at most, one (1) reviewing engineer for each county and we receive thousands of applications for review a year. Our internal records indicate that over the years we have, on average, completed reviews within 10 days. This includes weekends, holidays, out-of-office days, long queues, and staffing issues over the years. However, this is not a guaranteed review time, some applications may take longer or shorter depending on the scope and complexity of the application, and any additional extenuating circumstances. If the design is in compliance with our rules, the Wastewater Branch will issue an approval to construct to the engineer.

Approvals also depend on the time it takes your engineer to respond to comments, our internal records indicate that it has taken submitting engineers about 25 days on average to respond and address the Department of Health Wastewater Branch’s comments.

Additionally, our internal records indicate that the construction/installation of a new IWS can take about 200 days on average. Following this, the Department of Health expects to receive the final reports and forms that demonstrate that the system has been constructed/installed as approved. If done so, an approval to use the new wastewater system is sent to the engineer. If not, the approval to use the new wastewater system will be significantly delayed.