Council resolution urges prioritized recycled wastewater use for new housing

A lack of fresh water resources has long held back housing development on Maui. And now that there’s a post-disaster housing shortage, the Maui County Council will consider Friday a resolution calling for increased production and expansion of recycled wastewater use to make more potable water available for human consumption.

Mayor Richard Bissen’s administration said water for housing development is already a priority.

The resolution, introduced by South Maui Council Member Tom Cook, is on the Council’s regular meeting agenda Friday. The meeting begins at 9 a.m.

R-1 is the highest quality of treated wastewater. Although not for human consumption, it could be used for irrigation at parks, golf courses, hotels and condominium properties in West and South Maui, according to the resolution.

In order to reach the standard of “R-1” water, it must be oxidized, filtered and disinfected, according to the Hawaiʻi Department of Health.

Before the Aug. 8, 2023, wildfire, the Lahaina Wastewater Reclamation Facility produced 4.5 million gallons per day of R-1 water. Of that, an average of 3.16 million gallons per day went into underground injection wells in West Maui, according to the Council’s draft resolution.

(The use of underground injection wells in West Maui has been controversial for years, reaching the US Supreme Court in 2020. The high court’s ruling in the case led to a proposed Clean Water Act permit for the facility last year.)

In South Maui, a little more than 60% of the Kīhei Wastewater Reclamation Facility’s R-1 water is used for irrigation.

According to information provided to Cook’s office by the Department of Environmental Management’s Wastewater Reclamation Division, the county already has a six-year capital improvement plan for R-1 wastewater.

The draft Council resolution encourages the mayor and director of the Department of Environmental Management to invest in R-1 water production at the Kahului, Molokaʻi and Lānaʻi Wastewater Treatment Facilities, along with the expansion of the R-1 distribution system in West and South Maui. The Council also wants an annual progress report and asks the administration to explore public-private partnerships to expand R-1 wastewater distribution in West and South Maui.

Work has been ongoing for years to use R-1 water to off-set existing use of potable water, for landscaping, for example. That would make more potable water available for residential use.

Maui County’s largest wastewater treatment plant, the Wailuku-Kahului Wastewater Reclamation Facility, located near Kanahā Pond and the shoreline off of ‘Āmala Place, has an average plant flow of 5.54 million gallons per day. Because wastewater there does not go through ultraviolet treatment, the plant produces R-2 wastewater, a lower quality than R-1.

There are plans to upgrade the plant to produce R-1 wastewater, beginning in fiscal 2028. The projected cost is $50.8 million, including work to upgrade the plant itself and the R-1 water distribution system.

When asked for comment on the draft resolution, the Mayor’s Communications Office said: “Mayor Bissenʻs administration has always prioritized making more water available for housing development. The resolution underscores that the County Council shares our concerns.”

Here’s a breakdown from the Wastewater Reclamation Division on its six-year capital improvement plan for R-1 wastewater re-use.

In fiscal 2025:

• Kīhei Wastewater Reclamation Facility ultraviolet upgrade, $400,000 for design.
• North Kīhei reuse distribution system expansion, $1.5 million for construction.
• Honokōwai R-1 distribution system expansion, $400,000 for design.
• Lahaina recycled water force main construction/rehabilitation, $500,000 for design.

In fiscal 2026:

• Līloa Drive recycled water distribution line, $4 million for construction.
• South Maui reuse distribution system expansion in Wailea, $500,000 for preliminary engineering report and design.
• North Kīhei reuse distribution system expansion, $4 million for construction.
• Lahaina siphon and ditch distribution, $1 million for design.

In fiscal 2027:

• Kīhei WWRF ultraviolet upgrade, $4 million for construction.
• Honokōwai R-1 distribution system expansion, $4.3 million for construction.
• Lahaina recycled water force main construction/rehabilitation, $11.5 million for construction.

In fiscal 2028:

• South Maui reuse distribution system expansion in Wailea, $2 million for design.
• Wailuku-Kahului recycled water force main, $15 million for construction.
• Wailuku- Kahului recycled water pump station, $6 million for construction.
• Wailuku-Kahului WWRF R-1 upgrade, $1.8 million for design.
• Lahaina siphon and ditch distribution, $3.4 million for construction.

In fiscal 2029:

• Wailuku-Kahului recycled water force main, $10 million for construction..
• Lahaina siphon and ditch distribution, $5.2 million for construction.

In fiscal 2030:

• Wailuku-Kahului WWRF R-1 upgrade, $18 million for construction.

Current customer rates for R-1 reuse do not fully cover the cost of operating and maintaining the county’s R-1 distribution system. So funding for expansion will need to come from rate increases or other sources, such as the County’s general fund or a general obligation or revenue bonds.

The following shows the current approximate average volume of R-1 water used from Maui County wastewater reclamation facilities in Maui County in millions of gallons per day (mgd), and what remains available:

West Maui: Average total plant flow: 3.41 mgd; R-1 already re-used, 1.72 mgd; still available, 1.69 mgd; 50.4% re-used.

South Maui: Average total plant flow: 3.93 mgd; R-1 already re-used, 2.46 mgd; still available, 1.47 mgd; 62.6% re-used.

Central Maui: Average total plant flow: 5.54; R-1 already re-used, 0.19 mgd; still available, 0.29 mgd. (The Wailuku-Kahului Wastewater Reclamation Facility produces R-2 wastewater, which is a lower quality than R-1. Design work to upgrade that facility to R-1 water is set for fiscal 2028, and it’s expected to cost $1.8 million. Construction is planned for fiscal 2030, with an estimated price tag of $18 million.)

Lānaʻi: Average total plant flow: 0.35 mgd; R-1 already re-used, 0.09 mgd; still available, 0.26 mgd; 25.5% re-used. (R-1 water is obtained after treatment by Pūlama Lānaʻi’s polishing plant.)

Molokaʻi: Average total plant flow: 0.28 mgd; Secondary treated effluent already re-used, 0.00 mgd; secondary treated effluent available, 0.28 mgd; 0% re-used.

The Council meeting can be seen on Akakū Maui Community Media, cable Channel 53; or online via Teams at http://tinyurl.com/2p9zhjr2. Public testimony will be taken in person at the Council Chamber in the 8th floor of the Kalana O Maui Building in Wailuku, or by dialing 808-977-4067, code 234 794 559#.