State drinking water records

Hawaii drinking water systems

118 community water systems serve Hawaii and are listed below under 4 counties and on the pages of 134 cities and towns. Their own population figures add up to 1,507,181 people, a sum that counts people twice where one system sells water to another.

5 of them (4%) had at least one health-based violation in the last 10 years. 8 systems still have one unresolved.

109 rely mainly on groundwater and 9 on surface water, counting water bought from other systems.

117 systems filed a lead service line inventory listing 0 lead lines, 490 galvanized lines that must be replaced and 34,235 lines of unknown material.

21 systems are placed by the county their records name: EPA has no service area map for 20 of them, and 1 has one that does not line up with its own records.

Community water systems: 118
People served, sum of each system's own figure: 1,507,181
Systems with a health-based violation, last 10 years: 5
Systems with one unresolved: 8
Lead service lines in inventories: 0

Counties

4 counties

Each county counts the systems whose service area map reaches it. Systems placed only by a mailing address are listed on the county pages but not counted here.

County	Systems	People served	With a health-based violation, 10 years	With one unresolved
Hawaii County	33	143,185	0	1
Honolulu County	20	1,102,978	0	2
Kauai County	14	76,457	0	0
Maui County	30	165,719	1	4

Largest systems

System	Main county	People served	Main source	Health-based violations, 10 years	Unresolved
HNL-Windward-Pearl Harbor	Honolulu County	631,389	Groundwater	0	0
Waipahu-Ewa-Waianae	Honolulu County	217,479	Groundwater	0	0
Wailuku	Maui County	74,511	Surface water	0	0
Joint Base Pearl Harbor-Hickam	Honolulu County	65,230	Groundwater	0	1
Mililani	Honolulu County	50,573	Groundwater	0	0
Hilo	Hawaii County	39,477	Groundwater	0	0
Schofield Barracks	Honolulu County	37,920	Groundwater	0	0
Lihue-Kapaa	Kauai County	34,854	Surface water	0	0
Makawao	Maui County	29,868	Surface water	1	0
North Kona	Hawaii County	29,581	Groundwater	0	1
Wahiawa	Honolulu County	23,348	Groundwater	0	0
Lahaina	Maui County	20,065	Surface water	0	0
Marine Corps Base Hawaii	Honolulu County	16,300	Purchased groundwater	0	0
Kalaheo-Koloa	Kauai County	12,660	Groundwater	0	0
Waikoloa	Hawaii County	12,100	Groundwater	0	0

Systems with unresolved health-based violations

8 systems

System	Main county	People served	Main source	Unresolved
Kipu	Maui County	80	Purchased groundwater	2
Joint Base Pearl Harbor-Hickam	Honolulu County	65,230	Groundwater	1
North Kona	Hawaii County	29,581	Groundwater	1
Aliamanu	Honolulu County	6,406	Purchased groundwater	1
Lanai City	Maui County	3,200	Groundwater	1
Maunaloa-Kaluakoi	Maui County	1,000	Purchased groundwater	1
Kualapuu	Maui County	500	Groundwater	1
Kalaupapa NHP	Maui County	110	Groundwater	1

Back to All states

Counties come from the counties EPA lists each system serving, matched to 2024 Census counties; where EPA lists none, from the county coded in the system's ID, its service area map, or its mailing address. A county holding at least a fifth of a system's service area map is added when at least a fifth of that map lies in those counties. Towns are the ones EPA lists and the Census places such a map covers, always inside those counties. In New England, where EPA's town names a whole Town, it is not matched to the village of the same name. A system is not listed in a county holding less than a fifth of its map, or in a county or town its map reaches when the map lies mostly outside the counties EPA lists, so a page can leave out a system that serves part of the area. Methodology and limitations