Public water system · ID5420030
ActiveHollister City of
At a glance
City of Hollister (PWSID ID5420030) is an active community water system in Twin Falls County, Idaho. It reports serving 220 people through 120 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 February 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
220
Service connections
120
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Hollister compare with other water systems in Twin Falls County?
By EPA's size categories, City of Hollister is a very small system (500 people or fewer). Twin Falls County has 54 active public water systems. Its population served is well below the county average of 1,409 people per system, and accounts for 0.3% of the 76,088 people reported by systems filed under the county. Across Idaho, the 1,961 active systems average 899 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Hollister is well below 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. Idaho has 765 active community water systems, 39% of the state's 1,961 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,861 Idaho systems (95%) list groundwater as their primary source.
Who owns and regulates City of Hollister?
EPA lists City of Hollister as owned by a local government. The ID state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 16 of the 54 active systems in Twin Falls County (30%) are also owned by a local government.
Does City of Hollister have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in February 2026. The violations listed here began between April 2013 and February 2026. By type: 9 monitoring and reporting, 1 public notice, recordkeeping or other, 1 monitoring and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Chlorine (4 of them). EPA lists 7 as resolved, 4 as archived and 1 as unaddressed. 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. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-02-15 | Public notice, recordkeeping or otherFailure to Consult with State · code 20 | Groundwater Rulecode 0700 | No | Unaddressed |
| 2025-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2025-06-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Archived |
| 2024-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Archived |
| 2023-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Archived |
| 2015-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2014-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 2014-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2013-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 2013-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2013-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 2013-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | 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.
City of Hollister: frequently asked questions
Who runs City of Hollister?
City of Hollister (PWSID ID5420030) is a community water system owned by a local government. It is regulated by the ID state drinking water program.
How many people does City of Hollister serve?
City of Hollister reports serving 220 people through 120 service connections in Twin Falls County, Idaho.
Where does City of Hollister 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 City of Hollister 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 February 2026. 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 City of Hollister'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 February 2026. For current results, consult the system's annual water quality report, EPA ECHO, or the ID state drinking water program.
Where can I find City of Hollister's water quality report?
As a community water system, City of Hollister 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 Twin Falls County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Twin Falls City of | Twin Falls | 56,121 | Community | Groundwater |
| Kimberly City of | Twin Falls | 5,359 | Community | Groundwater |
| Buhl City of | Twin Falls | 4,518 | Community | Groundwater |
| Filer Water Works | Twin Falls | 2,858 | Community | Groundwater |
| Hansen City of | Twin Falls | 1,200 | Community | Groundwater |
| LDS Church Kimberly Sc | Twin Falls | 659 | Transient non-community | Groundwater |
Related pages
Working with water-system records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
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, “Hollister City of, PWSID ID5420030, Idaho”, https://aquacensus.com/water-systems/idaho/hollister-city-of-id5420030 (data as of October 1, 2026).