Overflow Action Days

The regional combined sewer system cannot always handle the amount of rain that falls in addition to the daily load of sewage and industrial waste. Heavy rainfalls and rapid snow melt can tax the region's sewage system, resulting in the release of untreated wastewater into the Chicago River system.

As little as 0.3 inches of rain, depending on the location and severity, can trigger a combined sewer overflow at any number of over 300 outfalls that flow directly into the Chicago River and Little Calumet River.

Our effort #OverflowActionDay is an attempt to relieve pressure on the sewer system to protect the river system. Based on the concept of Ozone Action Days, Overflow Action Days alert people before, during, and after rain storms when we need to minimize the amount of water going down our drains to reduce the chance of a combined sewer overflow.

Here are some things you can do:

Reduce your shower time: A ten minute shower can use as much as 40 gallons per minute. Depending on your showerhead, reducing your shower by three minutes can save between eight and 22 gallons of water.

Turn off the faucet: Turn off the faucet while brushing your teeth, doing dishes, washing your face or cleaning. Don't let the faucet run while cleaning vegetables. Put a jug of water in your refrigerator rather than letting the water run to get a cold drink.

Fix your faucet: A faucet that leaks 60 drops per minute will waste 192 gallons per month or 2,304 gallons per year. 

Delay laundry: Rainy days are lazy days. You have our permission. Delaying laundry will reduce the amount of soapy water that might end up in the river.

Delay dish washing machine: But if you must, use a dishwasher if you have one. Running a full dishwasher requires about 20 gallons of water compared to 40 gallons if you washed the same number of dishes by hand.

Flush less: Each flush can use between 1.6 to five gallons of water. Replace leaky toilets. Products bearing the waterSense label can save nearly 13,000 gallons of water per year. Don't use the toilet as a wastebasket. It's estimated 75% of indoor water use is in the bathroom and a quarter of that is through toilets.

Remove downspouts from storm sewer: Install rain barrels to capture water from downspots and store for later use. A downspot can dump as much as 12 gallons per minute into the sewer system.

Natural Landscaping: Use native vegetation as opposed to turf grass. Native plants have root systems that extend down three to more than 10 feet. In contrast, the root zone of turf grass typically extends only about three to four inches, according to the city's department of water management. 

Permeable Paving: Use paving blocks or grids, rather than asphalt or concrete, to reduce runoff into the sewer system.

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South Branch of the Chicago River, May 2020. Photo credit: The Watchers.

Since the the Metropolitan Water Reclamation District (MWRD) treats all water that enters its sewers, any water conserved effectively increases treatment capacity. If concentrated and timed properly, Overflow Action Days has the ability to offset combined sewer overflows throughout the Chicago River system. 

In 1975 the MWRD began construction of the Tunnel and Reservoir Plan (TARP). The system captures excess stormwater and wastewater until it can be treated at one of three MWRD plants. TARP was designed to prevent flooding and combined sewer overflows. However, while the system of tunnels and reservoirs has contributed to significant improvements in water quality, the reservoirs are not complete and climate change has exacerbated these issues.

Why should you act now?

The Chicago metropolitan area cannot rely solely on MWRD’s tunnel and reservoir system to solve flooding and combined sewer overflows (CSOs). Climate change forces us to act collectively and to support multi-pronged approaches to reduce the environmental and economic damages of these extreme rain events. 

Climate change is making it harder to manage stormwater and prevent CSOs in the Chicago metropolitan area. Weather data shows the number of 100-year rain events has nearly doubled over the past century due to a rapidly changing climate. The increase in 100-year rain events necessitates that we increase capacity in our sewer system, demanding both water conservation and water storage (TARP and on site storage). 


North Branch of the Chicago River, May 2020.

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