Public water system · IL0430270
ActiveDarien
At a glance
Darien (PWSID IL0430270) is an active community water system in DuPage County, Illinois. It reports serving 21,751 people through 8,944 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 2 violations for this system; none is health-based, and the most recent began in July 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
21,751
Service connections
8,944
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Darien compare with other water systems in DuPage County?
By EPA's size categories, Darien is a large system (10,001 to 100,000 people). DuPage County has 125 active public water systems. Its population served is about 3.2 times the county average of 6,865 people per system, and accounts for 2.5% of the 858,100 people reported by systems filed under the county. Across Illinois, the 3,872 active systems average 3,204 people each. Nationally, the average active community water system reports serving 6,703 people, so Darien is about 3.2 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. Illinois has 1,773 active community water systems, 46% of the state's 3,872 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 619 Illinois systems (16%) list purchased surface water as their primary source.
Who owns and regulates Darien?
EPA lists Darien as owned by a local government. The IL state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 32 of the 125 active systems in DuPage County (26%) are also owned by a local government.
Does Darien have drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in July 2024. The violations listed here began between June 1977 and July 2024. By type: 1 public notice, recordkeeping or other and 1 monitoring and reporting. The contaminants or rules involved are Consumer Confidence Rule and Gross alpha (excluding radon and uranium). EPA lists 1 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 |
|---|---|---|---|---|
| 2024-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 1977-06-30 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 2 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.
Darien: frequently asked questions
Who runs Darien?
Darien (PWSID IL0430270) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Darien serve?
Darien reports serving 21,751 people through 8,944 service connections in DuPage County, Illinois.
Where does Darien 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 Darien have any drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in July 2024. 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 Darien'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 2 violations for this system; none is health-based, and the most recent began in July 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Darien's water quality report?
As a community water system, Darien 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 DuPage County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Naperville | DuPage | 156,406 | Community | Purchased surface water |
| Wheaton | DuPage | 53,970 | Community | Purchased surface water |
| Downers Grove | DuPage | 49,425 | Community | Purchased surface water |
| Elmhurst | DuPage | 45,000 | Community | Purchased surface water |
| Lombard | DuPage | 44,476 | Community | Purchased surface water |
| Carol Stream | DuPage | 39,854 | Community | Purchased surface water |
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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, “Darien, PWSID IL0430270, Illinois”, https://aquacensus.com/water-systems/illinois/darien-il0430270 (data as of October 1, 2026).