Public water system · IA7740011
ActiveJohnston Municipal Water Supply
At a glance
Johnston Municipal Water Supply (PWSID IA7740011) is an active community water system in Polk County, Iowa. It reports serving 24,897 people through 7,657 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in May 2013.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
24,897
Service connections
7,657
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Johnston Municipal Water Supply compare with other water systems in Polk County?
By EPA's size categories, Johnston Municipal Water Supply is a large system (10,001 to 100,000 people). Polk County has 38 active public water systems, and Johnston Municipal Water Supply is the 4th-largest of them by population served. Its population served is about twice the county average of 12,857 people per system, and accounts for 5.1% of the 488,556 people reported by systems filed under the county. Across Iowa, the 1,828 active systems average 1,718 people each. Nationally, the average active community water system reports serving 6,703 people, so Johnston Municipal Water Supply is about 3.7 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. Iowa has 1,084 active community water systems, 59% of the state's 1,828 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 119 Iowa systems (6.5%) list purchased surface water as their primary source.
Who owns and regulates Johnston Municipal Water Supply?
EPA lists Johnston Municipal Water Supply as owned by a local government. The IA 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 38 active systems in Polk County (42%) are also owned by a local government.
Does Johnston Municipal Water Supply have drinking water violations?
EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in May 2013. The violations listed here began between July 1993 and May 2013. By type: 3 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (3 of them). EPA lists 3 as resolved and 1 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 |
|---|---|---|---|---|
| 2013-05-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2003-09-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1993-07-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
All 4 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.
Johnston Municipal Water Supply: frequently asked questions
Who runs Johnston Municipal Water Supply?
Johnston Municipal Water Supply (PWSID IA7740011) is a community water system owned by a local government. It is regulated by the IA state drinking water program.
How many people does Johnston Municipal Water Supply serve?
Johnston Municipal Water Supply reports serving 24,897 people through 7,657 service connections in Polk County, Iowa.
Where does Johnston Municipal Water Supply get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Johnston Municipal Water Supply have any drinking water violations?
EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in May 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 Johnston Municipal Water Supply'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 4 violations for this system; 1 is health-based, and the most recent began in May 2013. For current results, consult the system's annual water quality report, EPA ECHO, or the IA state drinking water program.
Where can I find Johnston Municipal Water Supply's water quality report?
As a community water system, Johnston Municipal Water Supply 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 Polk County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Des Moines Water Works | Polk | 246,055 | Community | Purchased surface water |
| Ankeny, City of | Polk | 76,207 | Community | Purchased surface water |
| Urbandale Water Utility | Polk | 45,605 | Community | Purchased surface water |
| Clive Water Department | Polk | 20,277 | Community | Purchased surface water |
| Altoona Water Supply | Polk | 19,565 | Community | Groundwater |
| Grimes Water Supply | Polk | 17,809 | 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, “Johnston Municipal Water Supply, PWSID IA7740011, Iowa”, https://aquacensus.com/water-systems/iowa/johnston-municipal-water-supply-ia7740011 (data as of October 1, 2026).