Public water system · HI0000101
ActiveHilo
At a glance
Hilo (PWSID HI0000101) is an active community water system in Hawaii County, Hawaii. It reports serving 39,477 people through 14,621 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, 12 are health-based, and the most recent began in January 2009.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
39,477
Service connections
14,621
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Hilo compare with other water systems in Hawaii County?
By EPA's size categories, Hilo is a large system (10,001 to 100,000 people). Hawaii County has 39 active public water systems, and Hilo is the largest of them by population served. Its population served is about 11 times the county average of 3,693 people per system, and accounts for 27% of the 144,021 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 Hilo is about 5.9 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 Hilo?
EPA lists Hilo 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. 23 of the 39 active systems in Hawaii County (59%) are also owned by a local government.
Does Hilo have drinking water violations?
Of the 12 most recent violations in EPA's records, 12 are health-based, and the most recent began in January 2009. The violations listed here began between March 1999 and January 2009. By type: 12 required treatment not met. The contaminant or rule involved most often is Surface Water Treatment Rule (12 of them). EPA lists 10 as archived and 2 as resolved. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status. 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 |
|---|---|---|---|---|
| 2009-01-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2000-01-01 | Required treatment not metFailure to Filter (SWTR) · code 42 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1999-12-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-11-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-10-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-09-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-08-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-07-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-06-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-05-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-04-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
| 1999-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Archived |
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.
Hilo: frequently asked questions
Who runs Hilo?
Hilo (PWSID HI0000101) is a community water system owned by a local government. It is regulated by the HI state drinking water program.
How many people does Hilo serve?
Hilo reports serving 39,477 people through 14,621 service connections in Hawaii County, Hawaii.
Where does Hilo 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 Hilo have any drinking water violations?
Of the 12 most recent violations in EPA's records, 12 are health-based, and the most recent began in January 2009. 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 Hilo'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, 12 are health-based, and the most recent began in January 2009. For current results, consult the system's annual water quality report, EPA ECHO, or the HI state drinking water program.
Where can I find Hilo's water quality report?
As a community water system, Hilo 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 Hawaii County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| North Kona | Hawaii | 29,581 | Community | Groundwater |
| Waikoloa | Hawaii | 12,100 | Community | Groundwater |
| South Kohala | Hawaii | 9,612 | Community | Surface water |
| South Kona | Hawaii | 6,512 | Community | Groundwater |
| Olaa-Mountain View | Hawaii | 6,467 | Community | Groundwater |
| North Kohala | Hawaii | 4,933 | 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, “Hilo, PWSID HI0000101, Hawaii”, https://aquacensus.com/water-systems/hawaii/hilo-hi0000101 (data as of October 1, 2026).