Public water system · HI0000335
ActiveWaipahu-Ewa-Waianae
At a glance
Waipahu-Ewa-Waianae (PWSID HI0000335) is an active community water system in Honolulu County, Hawaii. It reports serving 217,479 people through 40,092 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 6 violations for this system; none is health-based, and the most recent began in January 2012.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
217,479
Service connections
40,092
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Waipahu-Ewa-Waianae compare with other water systems in Honolulu County?
By EPA's size categories, Waipahu-Ewa-Waianae is a very large system (more than 100,000 people). Honolulu County has 38 active public water systems, and Waipahu-Ewa-Waianae is the 2nd-largest of them by population served. Its population served is about 7.3 times the county average of 29,687 people per system, and accounts for 19% 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 Waipahu-Ewa-Waianae is about 32 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 Waipahu-Ewa-Waianae?
EPA lists Waipahu-Ewa-Waianae 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 Waipahu-Ewa-Waianae have drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in January 2012. The violations listed here began between July 1992 and January 2012. By type: 6 monitoring and reporting. The contaminant or rule involved most often is Nitrate (2 of them). EPA lists 6 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 |
|---|---|---|---|---|
| 2012-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2012-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 1992-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1992-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
All 6 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.
Waipahu-Ewa-Waianae: frequently asked questions
Who runs Waipahu-Ewa-Waianae?
Waipahu-Ewa-Waianae (PWSID HI0000335) is a community water system owned by a local government. It is regulated by the HI state drinking water program.
How many people does Waipahu-Ewa-Waianae serve?
Waipahu-Ewa-Waianae reports serving 217,479 people through 40,092 service connections in Honolulu County, Hawaii.
Where does Waipahu-Ewa-Waianae 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 Waipahu-Ewa-Waianae have any drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in January 2012. 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 Waipahu-Ewa-Waianae'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 records list 6 violations for this system; none is health-based, and the most recent began in January 2012. For current results, consult the system's annual water quality report, EPA ECHO, or the HI state drinking water program.
Where can I find Waipahu-Ewa-Waianae's water quality report?
As a community water system, Waipahu-Ewa-Waianae 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 |
|---|---|---|---|---|
| Hnl-Windward-Pearl Harbor | Honolulu | 631,389 | 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, “Waipahu-Ewa-Waianae, PWSID HI0000335, Hawaii”, https://aquacensus.com/water-systems/hawaii/waipahu-ewa-waianae-hi0000335 (data as of October 1, 2026).