Public water system · HI0000438
ActiveKoolau Ranch
At a glance
Koolau Ranch (PWSID HI0000438) is an active non-transient non-community water system in Kauai County, Hawaii. It reports serving 60 people through 9 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's Safe Drinking Water Act records list no violations for this system.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
60
Service connections
9
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Koolau Ranch compare with other water systems in Kauai County?
By EPA's size categories, Koolau Ranch is a very small system (500 people or fewer). Kauai County has 19 active public water systems. Its population served is well below the county average of 4,167 people per system, and accounts for less than 0.1% of the 79,166 people reported by systems filed under the county. Across Hawaii, the 136 active systems average 11,181 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Koolau Ranch is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. Hawaii has 14 active non-transient non-community water systems, 10% of the state's 136 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 112 Hawaii systems (82%) list groundwater as their primary source.
Who owns and regulates Koolau Ranch?
EPA lists Koolau Ranch as privately owned. The HI state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 6 of the 19 active systems in Kauai County (32%) are also privately owned.
Does Koolau Ranch have drinking water violations?
No SDWA violations on record.
EPA's SDWA violation and enforcement data (via EPA ECHO, updated quarterly) lists no violations for Koolau Ranch. For the latest compliance status, check EPA ECHO for current compliance history.
Koolau Ranch: frequently asked questions
Who runs Koolau Ranch?
Koolau Ranch (PWSID HI0000438) is a non-transient non-community water system privately owned. It is regulated by the HI state drinking water program.
How many people does Koolau Ranch serve?
Koolau Ranch reports serving 60 people through 9 service connections in Kauai County, Hawaii.
Where does Koolau Ranch get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Koolau Ranch have any drinking water violations?
EPA's Safe Drinking Water Act records list no violations for this system.
Is Koolau Ranch's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's Safe Drinking Water Act records list no violations for this system. For current results, consult EPA ECHO, or the HI state drinking water program.
Where can I find Koolau Ranch's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Koolau Ranch is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Kauai County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Lihue-Kapaa | Kauai | 34,854 | Community | Surface water |
| Kalaheo-Koloa | Kauai | 12,660 | Community | Groundwater |
| Princeville | Kauai | 6,911 | Community | Groundwater |
| Kekaha-Waimea | Kauai | 5,998 | Community | Groundwater |
| Hanapepe-Eleele | Kauai | 5,592 | Community | Groundwater |
| Kilauea | Kauai | 3,420 | Community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Koolau Ranch, PWSID HI0000438, Hawaii”, https://aquacensus.com/water-systems/hawaii/koolau-ranch-hi0000438 (data as of October 1, 2026).