Sewer water at the floor drain on the east side
Joliet's East Side treatment plant serves a 14-square-mile area on both sides of the river, and the City's sewer plan describes it as having the oldest collection system, parts of it combined, carrying rain and sewage in the same pipe. Some old overflow points have been closed, but in a hard storm the lowest drain in an older basement can still take water back from the sewer.
A sump pump can't stop that. The fixes are on the sewer side: an overhead sewer that sends basement fixtures to a sealed ejector pit, a backflow device, and footing tile taken off the sewer.
Downtown and the 2019 flood maps
FEMA flood maps that took effect on February 15, 2019 added properties to the floodplain in the area the City describes as between the Des Plaines River and Eastern Avenue, from Ruby Street south to Hickory Creek. If your house is in that area, its mapped flood risk is higher than it was before 2019. The cost guide covers how flood insurance treats a sump pump.
Three to five days of pumping after a big rain
Joliet's FAQ tells residents that most sump pumps run for 3 to 5 days after a heavy rain. Over August 16-19, 2025, a station west-northwest of town logged 6.09 inches, and the Weather Service had reports of standing or flowing water on many Joliet streets. Days of steady pumping, on ComEd power that can drop in the same storm, is the case a backup pump is built for. Every Joliet ZIP is on the list, along with Crest Hill, Shorewood, Lockport, New Lenox and Romeoville, and Plainfield and Bolingbrook are close by.