Public water system · IL1090200

Active

Colchester

At a glance

Colchester (PWSID IL1090200) is an active community water system in McDonough County, Illinois. It reports serving 1,395 people through 620 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2009.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO public records.

Population served

1,395

Service connections

620

Primary source

SWP

Purchased surface water

System type

CWS

Community water system

System record

PWSIDIL1090200

System typeCommunity water system

Activity statusActive

Population served1,395

Service connections620

Primary water sourcePurchased surface water

Owner typeLocal government

Primacy agencyIL state drinking water program

City servedColchester

StateIllinois

ZIP—

CountyMcDonough County

How does Colchester compare with other water systems in McDonough County?

By EPA's size categories, Colchester is a small system (501 to 3,300 people). McDonough County has 21 active public water systems, and Colchester is the 5th-largest of them by population served. Its population served is about 12% below the county average of 1,588 people per system, and accounts for 4.2% of the 33,349 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 Colchester 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. 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 Colchester?

EPA lists Colchester 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. 12 of the 21 active systems in McDonough County (57%) are also owned by a local government.

Does Colchester have drinking water violations?

Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2009. The violations listed here began between August 2006 and January 2009. By type: 10 required treatment not met, 1 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Interim Enhanced Surface Water Treatment Rule (10 of them). EPA lists 12 as resolved. 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.

Began	Violation	Contaminant or rule	Health-based	Status
2009-01-01	Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24	Total coliform bacteria (TCR)code 3100	No	Resolved
2008-03-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2008-02-11	Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75	Public Noticecode 7500	No	Resolved
2008-02-01	Required treatment not metSingle Turbidity Exceed (Enhanced SWTR) · code 43	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2008-02-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-12-01	Required treatment not metSingle Turbidity Exceed (Enhanced SWTR) · code 43	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-12-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-05-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-04-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-03-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2007-03-01	Required treatment not metSingle Turbidity Exceed (Enhanced SWTR) · code 43	Interim Enhanced Surface Water Treatment Rulecode 0300	Yes	Resolved
2006-08-01	Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44	Interim Enhanced Surface Water Treatment Rulecode 0300	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.

Colchester: frequently asked questions

Who runs Colchester?

Colchester (PWSID IL1090200) is a community water system owned by a local government. It is regulated by the IL state drinking water program.

How many people does Colchester serve?

Colchester reports serving 1,395 people through 620 service connections in McDonough County, Illinois.

Where does Colchester 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 Colchester have any drinking water violations?

Of the 12 most recent violations in EPA's records, 10 are health-based, and the most recent began in January 2009. 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 Colchester'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, 10 are health-based, and the most recent began in January 2009. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.

Where can I find Colchester's water quality report?

As a community water system, Colchester 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 McDonough County

Water system	County	Population served	Type	Source
Macomb	McDonough	15,051	Community	Surface water
Western Illinois University	McDonough	8,000	Community	Purchased surface water
Bushnell	McDonough	2,972	Community	Groundwater
West Prairie Water Co-Op	McDonough	2,395	Community	Purchased groundwater
Blandinsville	McDonough	569	Community	Surface water
Good Hope	McDonough	536	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, “Colchester, PWSID IL1090200, Illinois”, https://aquacensus.com/water-systems/illinois/colchester-il1090200 (data as of October 1, 2026).