The Village of Oak Park is telling property owners to disconnect their gutter downspouts from the municipal sewer system, a low-cost step that can reduce the risk of basement flooding and sewage backups.

The village posted the advisory on Monday, Aug. 10, two weeks after severe storms on Monday, July 27 dumped nearly 2.5 inches of rain on the area and triggered a Cook County disaster declaration. The village said preventing backups starts with keeping stormwater out of the sewer system, and that disconnecting gutter downspouts is one of the most effective steps property owners can take.

The fix is simple. When downspouts feed directly into the sewer system, heavy rain can overwhelm pipes and force sewage back into basements. Redirecting roof runoff onto a lawn or rain barrel keeps that water out of the system entirely, according to the village's Basement Flooding Prevention page.

The July 27 storms produced seven confirmed tornadoes across the Chicago metro area, straight-line winds of 80 to 105 mph, and hail up to 3 inches in diameter, according to the National Weather Service. A CoCoRaHS weather station 1.5 miles south of Oak Park recorded 2.45 inches of rainfall that day. Multiple Cook County municipalities experienced power outages, downed power lines, tree removal emergencies, debris, localized roadway flooding and structural damage.

Cook County Board President Toni Preckwinkle issued a disaster declaration in the days following the storms, a step needed before Gov. JB Pritzker could issue a state declaration and seek federal aid, the Chicago Tribune reported. Cook County's Department of Emergency Management asked residents to submit storm damage assessments to help determine eligibility for state and federal assistance. That survey closed Wednesday, Aug. 5.

The village directs residents to oak-park.us/backupprevention for detailed guidance on how to disconnect downspouts. No deadline is attached to the advisory.