City of Oak Park issued the following announcement on Aug 27.
Our annual fire hydrant flushing program is beginning this week. This is necessary to help ensure hydrants don't freeze in the winter and it maintains the integrity of our water system.
This process can cause short periods of brown or "rusty" water for residents though. If you experience brown or "rusty" water in your tap run cold water in your laundry or bath tubs for few minutes until the water begins to run clear again.
If you have any questions please call the Department of Public Works at (248) 691-7497.
Original source can be found here.
Source: City of Oak Park