Water Treatment Facilities

Treatment Facility Water Source Service Area(s)
Kamole Weir Wailoa Ditch  Pukalani, Makawao, Haliimaile, Haiku
Piiholo Waikamoi Forest  Lower Kula
Olinda Waikamoi Forest  Upper Kula, Ulupalakua, Kanaoi
Lahaina Kanaha Stream  Lahaina
Mahinahina Honokohau Ditch  Lahaina, Napili, Wahikuli, Kahana, Alaeloa
Iao Iao/Waikapu Ditch  Kahului, Wailuku, Kihei, Paia, Puunene

Kamole Weir

The Kamole is the largest water treatment facility on Maui. Treated water from the facility goes to 6,687 services and can supply water to almost the entire region, or 9,865 services, if necessary. The facility is the primary source of water for nearly all of Upcountry during times of drought.


This facility was built to meet regulatory requirements and improve Lower Kula's water quality. Piiholo is located in the Makawao Forest Reserve adjacent to the Piiholo Reservoir. It uses direct filtration to treat its water and uses chlorine as a disinfectant.


The water that supplies the Olinda comes from the Waikamoi Rain Forest, and is stored in the Waikamoi and Kahakapao Reservoirs. These reservoirs will also supply the non-potable agricultural line currently under construction.


This facility is located above Lahainaluna High School. The Lahaina Water Treatment Facility was completed in June 1997 at a cost of about $10 million. The Lahaina facility utilizes microfiltration to treat surface water and chlorine to disinfect it after treatment.


The Mahinahina is located near the Kapalua airport and draws from three primary sources of raw surface water. Mahinahina utilizes pre-sedimentation to treat raw surface water. Rapid mix, flocculation, and direct filtration with a mixed media filter are used. After this process, chlorine is added for disinfection.