What Causes Sewer Backup in a House?

Tree roots are a major cause of sewer line damage. They seek out moisture and can grow into tiny cracks or loose joints in underground pipes. Once inside, they expand and create a dense mass that traps solids and completely blocks the pipe. This blockage prevents wastewater from leaving your home, causing it to back up through the lowest drain.

Clogs inside your home's plumbing can also cause a backup. Pouring cooking grease down a drain is a frequent culprit, as it hardens and sticks to pipe walls. Flushing non-flushable items like wipes, paper towels, or feminine hygiene products creates similar blockages. Even too much toilet paper or a buildup of hair and soap scum can slow flow enough to cause a problem.

Stop using all water immediately. Do not flush toilets, run sinks, or use appliances like washing machines or dishwashers. Every gallon you add will make the backup worse. If you know where your main water shutoff valve is, turning it off can prevent additional water from entering your plumbing system.

Avoid contact with the sewage water. It contains harmful bacteria, viruses, and other pathogens that pose serious health risks. Keep children and pets away from the affected area. If you must be in the space, wear rubber boots and gloves. Open windows if it is safe to do so to start ventilating the area.

• Do not try to use chemical drain cleaners.
• Do not attempt to plunge a drain connected to a main sewer backup.
• Turn off your home's electricity at the breaker if water is near outlets or appliances.
• Take photos of the damage from a safe distance for insurance purposes.
• Contact a plumber to address the sewer line blockage.
• Contact local water damage pros for cleanup and sanitation.

Sewage backup is a category 3 water loss, or "black water," which is grossly contaminated. Proper cleanup requires specialized equipment and disinfectants to make the area safe again. The pros have industrial-grade extractors, air scrubbers, and antimicrobial treatments. They follow strict protocols to remove sewage, dry the structure, and sanitize affected surfaces to prevent mold and lingering odors.

This process, often called sewage backup cleanup and sanitation, protects your health and your home's structure. The pros also use moisture mapping tools to find hidden dampness in walls and subfloors. Leaving any contamination or moisture behind can lead to severe mold growth and compromise building materials, requiring more extensive repairs later.