What to Do When Your Basement Floods with Sewage
Sewage in your basement requires immediate, careful action. Here's the step-by-step guide for protecting your family, stopping the damage, and getting professional help fast.
Step One: Stop All Water Use Immediately
The moment you discover sewage has backed up into your basement, stop all water use in the home. Flushing toilets, running sinks, using the dishwasher, or running the washing machine will add more volume to the backup. Every gallon you put into the drain system adds to what's already in your basement. Instruct everyone in the household — including children — not to use any water fixtures until a technician has assessed and cleared the line.
Step Two: Keep People and Pets Away
Raw sewage contains harmful bacteria, including E. coli and other pathogens, as well as viruses and parasites. This is a serious health hazard. Keep children and pets completely out of the affected area. If adults need to enter to assess the situation, wear rubber boots, waterproof gloves, and eye protection. Do not touch your face while in the affected area. Wash hands and any exposed skin thoroughly with soap and warm water after any contact. If sewage has contacted food, water, or pet food that was stored in the basement, it must be discarded.
Step Three: Document Before Cleanup Begins
Before any water is removed or cleanup begins, document the damage thoroughly. Take photographs and video of all affected areas: the depth of the water, what items have been contacted, the condition of flooring, walls, and stored belongings. This documentation is critical for insurance claims. Note the time the backup was discovered and when each step was taken. If your homeowner's policy includes sewer backup coverage, contact your insurance company as soon as possible — ideally before cleanup begins — to understand the claim process and whether they require specific procedures to be followed.
Step Four: Call a Sewer Professional to Clear the Line
Even if you're focused on cleanup, the first call should be to a sewer service company. If the blockage hasn't been cleared, the basement will flood again the moment water is used. A technician with a camera and jetting equipment can identify what caused the backup, clear the obstruction, and confirm the line is open before any cleanup effort begins. Cleanup without clearing the line is putting water into a bucket with a hole in the bottom.
Step Five: Water Extraction and Drying
Once the line is confirmed clear, water must be removed from the basement as quickly as possible. Time is critical — sewage water accelerates mold growth in porous materials like drywall, insulation, and wood framing within 24 to 48 hours. A wet/dry vac can handle small volumes. For larger backups, a water extraction service or restoration company with commercial equipment is the appropriate resource. After extraction, the space needs aggressive drying with dehumidifiers and air movers — not just ventilation with open windows. In Minnesota's winter months, cold air outside the building can actually impede effective drying.
Step Six: Proper Sanitization
Any surface that contacted sewage water must be properly disinfected, not just dried. Hard surfaces — concrete floors, vinyl, ceramic tile — can be cleaned with appropriate EPA-registered disinfectants after visible contamination is removed. Porous materials — carpet, drywall, insulation, wood stud framing, ceiling tiles — that were contacted by sewage are typically not salvageable and should be removed and discarded. This is a source of genuine cost in a sewage backup situation. The material itself may not look severely damaged, but porous materials hold pathogens even after drying and cannot be reliably sanitized. A professional remediation contractor will guide you through what can be saved and what must go.
Preventing Future Backups
After the immediate crisis is resolved, address the underlying cause. Get a camera inspection to understand what caused the backup and whether your sewer lateral has other vulnerabilities. If tree roots were the cause, discuss long-term solutions rather than just clearing the line again. If the problem was a collapsed or deteriorated pipe, understand your repair options. Consider installing a backwater valve — a one-way valve that allows sewage to flow out of the home but prevents city sewer surges from flowing back in. Some Minnesota counties have programs to assist with the cost of backwater valve installation.
Need help now? Call Minnesota Sewer Pros at 612-816-8013. We provide emergency sewer response across 19 Minnesota counties.