The new KSDF will embrace practical measures to minimize reliance on fossil fuels, and incorporate materials and systems that support a healthy environment. By maximizing opportunities to provide natural light, natural ventilation, and nighttime cooling, the design will result in reduced operational costs. Additional considerations have been taken to promote extended Facility life, ensuring BWS and the surrounding community receive the most benefit from the new Facility.
Project Status
SEPTEMBER 2025
BWS recently approved the pilot test report submitted by Kalaeloa Desalco, which detailed findings and recommendations from the Project’s Pilot Testing Study completed in January 2024.
With this approval, BWS concluded desalinated water produced during the Pilot Test Study was a reasonable match to their existing water supply. They also concluded desalinated water from the new KSDF would not cause any detrimental impact to existing distribution pipes or customer assets.
Where will the plant be built?
The new facility will be located on a 20-acre empty lot in Campbell Industrial Park owned by BWS at 91-447 Olai Street (TMK: 9-1-31:28). The project site will include an administration building, laboratory, office, a building for the processing equipment, along with grading, drainage, roads, parking, utilities, fencing, landscaping, and security systems.
Why do we need this project?
The demand for fresh water from BWS’s ‘Ewa system is approaching capacity, as the district’s population is expected to grow by about 30 percent, or 50,000 people, by 2040. The seawater desalination plant will supplement BWS’s ongoing efforts to encourage conservation, use recycled water for non-potable water demands, and leverage brackish and saline aquifer supplies where possible.
What is the timeline for this project?
In 2023, BWS awarded a design-build-operate-maintain services contract to Kalaeloa Desalco LLC to design, build and operate the facility, with a targeted operational start date in 2027. This date is subject to change.
What are the benefits of seawater desalination?
For the City & County of Honolulu, the Kalaeloa Seawater Desalination Facility will produce high-quality drinking water for local customers, diversify O‘ahu’s fresh water production sources, and improve Hawai‘i’s water resilience to climate change.
What is seawater desalination?
Desalination describes the process of producing fresh water from a saline source, such as seawater. The process uses reverse osmosis, which pressurizes seawater to safely separate fresh water from the mineral salts when it is passed through a semi-permeable membrane within the system.
The reverse osmosis membrane separation method that the Kalaeloa Seawater Desalination Facility will use is the widely accepted technology for converting seawater into fresh water.
The KSDF will draw seawater to be treated through seawater reverse osmosis treatment processes with a final production capacity of 1.7 million gallons per day (MGD), with additional expandable future phases. Treated water will ultimately be discharged and blended with existing BWS water. The new Facility will also feature an administration building with accommodations for public visitors. Design of the KSDF will support sustainability initiatives set forth by BWS.
