Public water system · IL0374870
ActiveSomonauk
At a glance
Somonauk (PWSID IL0374870) is an active community water system in DeKalb County, Illinois. It reports serving 1,860 people through 741 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in July 2007.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
1,860
Service connections
741
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Somonauk compare with other water systems in DeKalb County?
By EPA's size categories, Somonauk is a small system (501 to 3,300 people). DeKalb County has 43 active public water systems. Its population served is about 16% below the county average of 2,220 people per system, and accounts for 1.9% of the 95,450 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 Somonauk 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. Illinois has 1,773 active community water systems, 46% of the state's 3,872 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,808 Illinois systems (73%) list groundwater as their primary source.
Who owns and regulates Somonauk?
EPA lists Somonauk 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. 13 of the 43 active systems in DeKalb County (30%) are also owned by a local government.
Does Somonauk have drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in July 2007. The violations listed here began between June 1977 and July 2007. By type: 2 required treatment not met, 2 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Lead and Copper Rule (2 of them). EPA lists 3 as resolved and 2 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 |
|---|---|---|---|---|
| 2007-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 1995-08-01 | Required treatment not metOCCT/SOWT Study/Recommendation · code 57 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 1995-01-12 | Required treatment not metOCCT/SOWT Study/Recommendation · code 57 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 1992-10-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1977-06-30 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 5 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.
Somonauk: frequently asked questions
Who runs Somonauk?
Somonauk (PWSID IL0374870) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Somonauk serve?
Somonauk reports serving 1,860 people through 741 service connections in DeKalb County, Illinois.
Where does Somonauk 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 Somonauk have any drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in July 2007. 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 Somonauk'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 5 violations for this system; 2 are health-based, and the most recent began in July 2007. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Somonauk's water quality report?
As a community water system, Somonauk 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 DeKalb County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Dekalb | DeKalb | 40,290 | Community | Groundwater |
| Sycamore | DeKalb | 18,500 | Community | Groundwater |
| Sandwich | DeKalb | 7,156 | Community | Groundwater |
| Northern Illinois University-Dekalb | DeKalb | 6,500 | Community | Purchased groundwater |
| Genoa | DeKalb | 5,298 | Community | Groundwater |
| Cortland | DeKalb | 4,398 | 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, “Somonauk, PWSID IL0374870, Illinois”, https://aquacensus.com/water-systems/illinois/somonauk-il0374870 (data as of October 1, 2026).