The Maui Department of Water Supply serves five main sections within the County:
- Central Maui
- Upcountry Maui
- West Maui
- East Maui
The system with the most customers is the Central system, which includes Wailuku, Paia, Kahului, Puunene, and Kihei.
The next largest system is the Upcountry water system, which is actually the largest geographically. This includes Kula, Pukalani, Makawao, and Haiku.
Lahaina is third, then Molokai, and then Hana. Water on the island of Lanai is provided by a private company.