OAK BROOK, IL · DuPage County

OAK BROOK Water System

Current status

No open violations on record as of July 4, 2026.

This system's next federally required Consumer Confidence Report is due July 1, 2027, under the EPA's revised reporting rule.

Data sourced from the EPA ECHO database (SDWA bulk download), last refreshed July 4, 2026. This is a record-keeping and public-information tool — it does not replace Illinois’s official records. Always confirm current status with Illinois before making decisions based on this information.

System facts

System ID (PWSID): IL0430700
System type: Community Water System
Population served: 9,400
Service connections: 3,295
Ownership: local government
Water source: surface water (rivers, lakes, or reservoirs)

Violation history

Maximum Contaminant Level Violation, Average
Health-based
Combined Radium (-226 and -228)
October 1, 1989 – March 9, 1992
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Gross Alpha, Excl. Radon and U
December 1, 1985 – June 11, 1986
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Combined Radium (-226 and -228)
October 4, 1985 – October 3, 1989
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Gross Alpha, Excl. Radon and U
December 2, 1981 – December 1, 1985
Archived
Monitoring, Regular
—
Gross Alpha, Excl. Radon and U
June 30, 1977 – June 29, 1981
Archived

Resolved addressed and confirmed by the stateArchived closed in EPA's records (typically due to age or a data correction)

Period	Violation	Contaminant / rule	Health-based	Status
October 1, 1989 – March 9, 1992	Maximum Contaminant Level Violation, Average	Combined Radium (-226 and -228)	Health-based	Resolved
December 1, 1985 – June 11, 1986	Maximum Contaminant Level Violation, Average	Gross Alpha, Excl. Radon and U	Health-based	Resolved
October 4, 1985 – October 3, 1989	Maximum Contaminant Level Violation, Average	Combined Radium (-226 and -228)	Health-based	Resolved
December 2, 1981 – December 1, 1985	Maximum Contaminant Level Violation, Average	Gross Alpha, Excl. Radon and U	Health-based	Archived
June 30, 1977 – June 29, 1981	Monitoring, Regular	Gross Alpha, Excl. Radon and U	—	Archived

Resolved addressed and confirmed by the stateArchived closed in EPA's records (typically due to age or a data correction)

Enforcement actions

June 23, 2025State Public Notification received1 linked violation
June 11, 2025State Compliance achieved1 linked violation
November 13, 2024State Compliance achieved1 linked violation
November 1, 2024State Violation/Reminder Notice1 linked violation
October 15, 2024State Violation/Reminder Notice1 linked violation
October 15, 2024State Public Notification requested1 linked violation
October 2, 2024State Public Notification received3 linked violations
February 27, 2024State Compliance achieved2 linked violations
October 11, 2023State Public Notification requested2 linked violations
March 9, 1992State Compliance achieved2 linked violations
October 25, 1991State Public Notification received1 linked violation
July 26, 1991State Public Notification received1 linked violation
April 29, 1991State Public Notification received1 linked violation
January 29, 1991State Public Notification received1 linked violation
January 28, 1991State Public Notification received1 linked violation
October 29, 1990State Public Notification received2 linked violations
July 27, 1990State Public Notification received1 linked violation
April 27, 1990State Public Notification received1 linked violation
January 29, 1990State Public Notification received1 linked violation
June 11, 1986State Compliance achieved1 linked violation

Contact

O'MALLEY, TIM

630-368-5276

OAK BROOK, IL 60523