Public water system · HI0000331
ActiveHnl-Windward-Pearl Harbor
At a glance
Hnl-Windward-Pearl Harbor (PWSID HI0000331) is an active community water system in Honolulu County, Hawaii. It reports serving 631,389 people through 106,491 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2013.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
631,389
Service connections
106,491
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Hnl-Windward-Pearl Harbor compare with other water systems in Honolulu County?
By EPA's size categories, Hnl-Windward-Pearl Harbor is a very large system (more than 100,000 people). Honolulu County has 38 active public water systems, and Hnl-Windward-Pearl Harbor is the largest of them by population served. Its population served is about 21 times the county average of 29,687 people per system, and accounts for 56% of the 1,128,119 people reported by systems filed under the county. Across Hawaii, the 136 active systems average 11,181 people each. Nationally, the average active community water system reports serving 6,703 people, so Hnl-Windward-Pearl Harbor is about 94 times that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Hawaii has 119 active community water systems, 88% 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 Hnl-Windward-Pearl Harbor?
EPA lists Hnl-Windward-Pearl Harbor as owned by a local government. 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. 8 of the 38 active systems in Honolulu County (21%) are also owned by a local government.
Does Hnl-Windward-Pearl Harbor have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2013. The violations listed here began between January 2008 and October 2013. By type: 11 monitoring and reporting and 1 contaminant level above the legal limit. The contaminants or rules involved are Total coliform bacteria (TCR), Cadmium, Alachlor (Lasso) and Thallium. EPA lists 12 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2013-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Cadmiumcode 1015 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Alachlor (Lasso)code 2051 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Thalliumcode 1085 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Glyphosatecode 2034 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Ethylene dibromide (EDB)code 2946 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2,4-Trichlorobenzenecode 2378 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | cis-1,2-Dichloroethylenecode 2380 | No | Resolved |
| 2008-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Hnl-Windward-Pearl Harbor: frequently asked questions
Who runs Hnl-Windward-Pearl Harbor?
Hnl-Windward-Pearl Harbor (PWSID HI0000331) is a community water system owned by a local government. It is regulated by the HI state drinking water program.
How many people does Hnl-Windward-Pearl Harbor serve?
Hnl-Windward-Pearl Harbor reports serving 631,389 people through 106,491 service connections in Honolulu County, Hawaii.
Where does Hnl-Windward-Pearl Harbor 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 Hnl-Windward-Pearl Harbor have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2013. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Hnl-Windward-Pearl Harbor'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. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2013. For current results, consult the system's annual water quality report, EPA ECHO, or the HI state drinking water program.
Where can I find Hnl-Windward-Pearl Harbor's water quality report?
As a community water system, Hnl-Windward-Pearl Harbor must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Honolulu County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Waipahu-Ewa-Waianae | Honolulu | 217,479 | Community | Groundwater |
| Joint Base Pearl Harbor-Hickam | Honolulu | 65,230 | Community | Groundwater |
| Mililani | Honolulu | 50,573 | Community | Groundwater |
| Schofield Barracks | Honolulu | 37,920 | Community | Groundwater |
| Wahiawa | Honolulu | 23,348 | Community | Groundwater |
| Marine Corps Base Hawaii | Honolulu | 16,300 | Community | Purchased 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, “Hnl-Windward-Pearl Harbor, PWSID HI0000331, Hawaii”, https://aquacensus.com/water-systems/hawaii/hnl-windward-pearl-harbor-hi0000331 (data as of October 1, 2026).