Detroit runs mostly on a combined sewer, which means stormwater and household sewage share the same pipe under the alley. The regional system is built to handle about 1.7 inches of rain in an hour or 3.31 inches in a day, according to the Great Lakes Water Authority. On June 26, 2021, the City Airport gauge recorded 5.77 inches, the biggest single-day total in 80 years. Thousands of basements filled, and the average water height in FEMA claims was 10 inches.
Here's the part that surprises people. A sump pump moves groundwater out from around your foundation. It does nothing when combined sewer surcharges push water back up your lateral and out the floor drain. That's a job for a backwater valve, a flap valve we install on the sewer line under the basement floor. It lets wastewater leave and closes when flow reverses. While it's closed, you hold off on flushing and laundry so the flap stays shut. For homes with both risks, the city's setup pairs the valve with a sump pump and an overflow. Our sewer system backups service covers the lateral side of that work.