Overview

• The Metropolitan Water Reclamation District of Greater Chicago (MWRD) has declared an Overflow Action Day Alert for Tuesday, May 20, 2025, due to forecasted heavy rain.
• Chicago-area residents are advised to limit water use by delaying showers, baths, laundry, and dishwashing, and by flushing toilets less frequently during the alert.
• Heavy rain has pushed daily wastewater treatment volumes from an average of 1.47 billion gallons to over 2 billion gallons, reducing the sewer system's storage buffer.
• The alert aims to mitigate flooding, sewer backups, and potential contamination of the Chicago River and Lake Michigan.
• Showers and storms are expected to continue into Wednesday, with meteorologists warning of possible severe weather in southern counties.