KIHEI-WAILEA - FlushAware

Where does your drinking water come from?

Drinking water is transported from the rivers and ground waters of Na Wai Eha, Maui’s Four Great Waters of West Maui, across Central Maui to South Maui, where it enters resident homes to be used for household activities and is then flushed down the toilet or drain.
Where does your untreated sewage go?

Untreated sewage is conveyed through sewer mains to the Kihei-Wailea Wastewater Reclamation Facility, then the water is treated to "secondary¹" standards.
Effluent disinfection & disposal
Just under half of recent secondary municipal wastewater effluent in South Maui (48.2%) is UV disinfected ² and goes to R-1 ³ reuse irrigation, the balance (51.8%) contains significant fecal indicator bacteria and discharges as R-3 ⁴ into injection wells. Detailed County of Maui plant flow reports.
Effluent reaches the Pacific Ocean
Injected non-disinfected effluent releases into groundwater systems that flow into Pacific Ocean nearshore waters centered around Cove Park (Hunt 2007), where it emerges often through the reef itself, via openings that present as direct pathways from the wastewater treatment plant to the reef, similar to the flow shown with green dye in the video below.

See wastewater exiting the reef at Kahekili Beach Maui

Learn About Your Water Journey

Drinking Water Sources

Interesting Facts about Drinking Water Sources

From County of Maui: "If you live in Upcountry Maui, your water is surface water from the streams in East Maui. It's treated and disinfected at one of our three water treatment facilities (Kamole, Piiholo, Olinda) before it's delivered to your home. Customers in Haiku get their water from the Haiku or Kaupakalua wells and/or the Kamole Weir. Hana and Molokai also use groundwater. Lahaina has a mix of surface water and groundwater. The water treatment facilities for West Maui are located above Lahainaluna School and near the Kapalua Airport.

For Central Maui (Kahului, Wailuku, Waihe'e, Waikapū, Waiehu, Ma'alaea, Kihei, Wailea, Makena, Sprecklesville and Paia) your water is from surface and groundwaters of Na Wai Eha, Maui’s Four Great Waters of West Maui, which includes the ‘Īao Aquifer under the West Maui Mountains. That water is naturally filtered by lava rocks, disinfected, and sent to your home. A small amount of filtered surface water is added to the Central System at the Iao WTF."

The Iao and Waihee aquifer region has been designated by the Commission on Water Resources Management as a “water management area” due to over pumping. This points out that water reuse can alleviate stress on our primary drinking water source for Central & South Maui.

Na Wai Eha, The Four Great Waters of West Maui
Municipal Disposal Methods

Kihei-Wailea municipal wastewater reclamation facility disposal methods

Effluent Disposal Methods

48.2%

Disinfected Irrigation Use

51.8%

Non-disinfected Nearshore Injection Wells

On average, about 52% of recent effluent volumes are discharged into nearshore injection wells at the Kihei Wastewater Reclamation Facility, with about 48% used for irrigation reuse. See detailed County of Maui plant flow reports.

"Interested in seeing present and potential future Kihei wastewater reclamation facility irrigation reuse locations?

View Irrigation Reuse Locations View Irrigation Reuse Locations gallery image - 2 View Irrigation Reuse Locations gallery image - 3 View Irrigation Reuse Locations gallery image - 4
Injection Well Plume

Aerial photomosaic showing the Kihei non-disinfected injected municipal wastewater effluent plume as estimated by numerical modeling in South Maui, Hawaii

The non-disinfected effluent plume is roughly a mile long and a mile wide (0.93 mi, or 1.5 km) and flows beneath the urban strip seaward of the main highway. Colors represent effluent concentration, from 100 percent effluent at the plume core to 5 percent effluent at the outer plume margin. Popular nearshore recreations areas including Kalama Park and Cove Park are found within the modeled injection well plume area. (Hunt 2007).

This model shows a visualization of the non-disinfected underground municipal wastewater plume in Kihei, Maui
An injection well is a hole in the earth with a pipe inserted that pumps wastewater hundreds of feet into the ground before it is released into groundwater. This cutaway diagram of a modeled underground wastewater plume underneath Kihei, Maui, shows the deep puncture of the well much like a giant hypodermic needle, with colored surfaces of equal effluent concentration are shown at 20, 40, 60, and 80 percent effluent, with the highest concentrations of wastewater shown in red found near the surface because effluent is freshwater so floats above saline nearshore groundwater. (Hunt 2007).
Visualization showing modeled injection plume at Kihei, Maui.
This visualization reveals the injection well plume core and portrays plume extent to an outer limit of 5 percent effluent.
The injection plume encompasses 0.93 miles of coastline and its central axis is aligned southwest, extending through the south part of Kalama Park. (Hunt 2007).