Why Our Sewers Overflow When It Rains

More than 100 years ago, South Bend, Mishawaka, Elkhart and many other cities built storm sewers to carry rainwater and melting snow away from homes, businesses and  streets. In those horse-and-buggy days, these cities didn't have sewage treatment or even indoor plumbing.

When indoor plumbing came later, homeowners and businesses owners hooked their sewage lines to the existing storm sewers, combining storm water and raw sewage into one pipe. The pipes emptied directly into the river, until the 1950's when sewage treatment plants were built.

This was common practice in many U.S. cities, especially in the Northeast and Midwest.

During dry weather, a "combined" sewer system works much like a seperated sewer -- carrying all sewage to the treatment plant for treatment.

However, when it rains or snow melts, the sewers can be overloaded with incoming stormwater. When this happens, the sewers are designed to flow over internal dams in the underground pipes and into nearby streams and rivers. If they didn't have this release valve, raw sewage would back up into people's basements and streets.

Millons of gallons of untreated sewage and rainwater enter the river each year. State and federal regulations require cities to develop longterm plans to reduce these overflows.

River Report, October 2005* (pdf, 1.40 MB)

View the CSO Notification Page

*Acrobat Reader Required

Waste Water Treatment Plant
3113 Riverside Dr.
South Bend, Indiana 46628
574.277.8515