The first thirty minutes, in order
Stop every water fixture in the house, including the dishwasher and washing machine. Say it out loud to everyone home, because an unaware family member starting laundry is the most common way a contained backup becomes a flood.
Keep people and pets out and close the door to the affected space. Sewage is category 3 contaminated water. If outlets, the furnace, the water heater or the sump pump sit near standing water, cut those circuits at the breaker, and do not wade in to reach a panel that is already in the wet area.
Do not open a cleanout while the line is under pressure. Then report to your sewer utility, and only then call a plumber.
Who to call, by where you live
St. Louis City and St. Louis County are served by the Metropolitan St. Louis Sewer District, which operates a 24-hour customer service line and dispatches crews to check the public main. Reporting establishes a record and can shift responsibility for the repair off your bill entirely.
Wentzville, St. Charles, St. Peters, O'Fallon, Cottleville and Lake Saint Louis operate or contract their own sanitary sewer service, so the equivalent call is to that city's sewer or public works department. If you are on septic, there is no utility to call; a backup with a full tank usually means pumping first and inspection second.
Storm-driven backups look different
If the water arrived during heavy rain and is relatively clear or grey rather than black, you may be seeing a surcharged combined sewer rather than a clog in your line. Older parts of St. Louis City and the inner-ring suburbs sit on combined systems that carry sanitary flow and stormwater in the same pipe, and when the system fills, water can push back up through a basement floor drain in a house that was fine an hour earlier.
That is a system condition, not a blockage you can cable away. Report it, document it, and ask a plumber about a backwater valve, which closes when flow reverses.
Finding someone nearby, quickly
Browse plumbing pros below, or use the city pages to narrow to your municipality. Every listing shows the services offered and service areas so you can see who actually covers your address rather than dispatching from across the metro.
Requesting quotes through the form reaches several local pros at once, which is usually faster than working down a list one call at a time.
