Chicago-area residents are being asked to use less water to help prevent overflowing of storm water management systems across the region this week.

According to the Metropolitan Water Reclamation District, an “Overflow Action Day” has been issued Sunday, with rain expected to arrive in waves over the coming days.

Rain is expected to persist into Tuesday, with some parts of the area seeing at least 1-to-3 inches of rain, with locally heavier totals possible.

According to the alert, residents are being asked to delay taking baths or showers when possible. They are also being asked to flush toilets less frequently, and to avoid high-water-usage appliances like dishwashers and washing machines.

Overflow action alerts are used by MWRD in an effort to keep excess water from entering sewer systems. If too much water enters those systems, it can lead to flooding, including into the basements of residences and businesses.

Particularly severe flooding can result in the release of untreated or partially treated wastewater into the Chicago River.

The heaviest rain could fall Sunday night and into Monday morning, causing some localized street flooding in areas with poor drainage. Falling leaves could also cause sewer drains to clog, which could exacerbate that flooding.