In the Chicagoland area, there is no single cause behind every sewer backup.
Heavy rain can put additional pressure on drainage and sanitary sewer systems, especially when the ground is already saturated. Older sewer laterals can develop cracks, deterioration, root intrusion, or blockages. Basement floor drains, toilets, laundry areas, ejector systems, and other below-grade plumbing can become entry points when a system backs up.
Properties along the Fox River and surrounding waterways can face another layer of complexity during major rain and flooding events. High groundwater, saturated soil, drainage problems, and sewer issues can all happen at the same time.
Farther into McHenry and Kane counties, some properties rely on private septic systems rather than municipal sewer service. Septic backups require the same basic priority: stop the source, control contamination, and clean the affected property properly.
Not every backup has the same cause, so the cleanup process needs to account for what actually happened.