Public water system · ID5420058
ActiveTwin Falls City of
At a glance
City of Twin Falls (PWSID ID5420058) is an active community water system in Twin Falls County, Idaho. It reports serving 56,121 people through 19,273 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
56,121
Service connections
19,273
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Twin Falls compare with other water systems in Twin Falls County?
By EPA's size categories, City of Twin Falls is a large system (10,001 to 100,000 people). Twin Falls County has 54 active public water systems, and City of Twin Falls is the largest of them by population served. Its population served is about 40 times the county average of 1,409 people per system, and accounts for 74% 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 Twin Falls is about 8.4 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. 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 Twin Falls?
EPA lists City of Twin Falls 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 Twin Falls 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 2012 and February 2026. By type: 7 monitoring and reporting, 3 public notice, recordkeeping or other, 1 monitoring and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Public Notice (3 of them). EPA lists 9 as resolved and 3 as archived. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-02-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2026-02-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Archived |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2022-07-01 | Monitoring and reportingInitial, Follow-up, or Routine Source Water M/R · code 56 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2022-07-01 | Monitoring and reportingInitial, Follow-up, or Routine Source Water M/R · code 56 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2022-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2015-02-17 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Archived |
| 2012-07-12 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2012-05-05 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2012-05-05 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2012-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Arseniccode 1005 | Yes | 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 Twin Falls: frequently asked questions
Who runs City of Twin Falls?
City of Twin Falls (PWSID ID5420058) 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 Twin Falls serve?
City of Twin Falls reports serving 56,121 people through 19,273 service connections in Twin Falls County, Idaho.
Where does City of Twin Falls 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 Twin Falls 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 Twin Falls' 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 Twin Falls' water quality report?
As a community water system, City of Twin Falls 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 |
|---|---|---|---|---|
| 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 |
| Amalgamated Sugar Twin Falls | Twin Falls | 460 | Non-transient non-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, “Twin Falls City of, PWSID ID5420058, Idaho”, https://aquacensus.com/water-systems/idaho/twin-falls-city-of-id5420058 (data as of October 1, 2026).