The short answer
Overwhelmed Municipal Sewer Systems
During a heavy rainstorm, the volume of water entering the sewer system can exceed its designed capacity. This is often due to inflow from downspouts or sump pumps wrongly connected to sanitary sewers. When the main public sewer line is full, there is nowhere for your home's wastewater to go. This hydraulic overload forces sewage to reverse its flow and come back up your drains.
Aging public infrastructure with cracks or broken pipes also allows significant groundwater to seep in, a process called infiltration. Combined sewer systems, which carry both stormwater and sewage, are especially vulnerable to overloading. When the treatment plant cannot handle the surge, backups become more likely throughout the connected neighborhood, affecting multiple homes at once.
Issues with Your Private Sewer Line
Problems on your property can also cause a backup during rain. Tree roots often infiltrate older sewer pipes, creating a partial blockage that catches debris. When heavy rain saturates the ground, extra water seeps through these root masses and cracks, further reducing flow. This combination of a pre-existing obstruction and added water can create a complete clog right at your property line.
A sagging section of pipe, known as a belly, can also trap waste and cause frequent blockages. During a storm, the sudden influx from the city main can push material against this low point, sealing it shut. If your private line has a reverse slope or is damaged, it cannot drain properly when the public system is under pressure.
- Tree root intrusion into pipe joints or cracks.
- Collapsed, sagging, or broken sections of clay or cast iron pipe.
- Grease, wipes, or other debris forming a partial blockage.
- Poor installation or a pipe with an incorrect slope.
- Corrosion in older metal pipes reducing the interior diameter.
- Damage from soil shifting when the ground is saturated.
The Role of Sump Pumps and Foundation Drains
Many homes have foundation drain tiles or a sump pump pit designed to collect groundwater. If these systems are mistakenly connected to the home's sanitary sewer line, they illegally discharge hundreds of gallons of stormwater into it. This direct inflow during a downpour can instantly overwhelm the capacity of your private line and the public sewer, triggering a backup directly in your basement or lowest bathroom.
Correcting these improper connections is a critical plumbing task. A qualified plumber can inspect your system to ensure sump pumps and foundation drains discharge to the yard or storm sewer, not the sanitary line. This prevents your home from contributing to the sewer overload and reduces your personal risk of a messy and hazardous backup.
Immediate Actions During a Backup
If sewage begins to back up into your home, prioritize safety. Avoid all contact with the contaminated water, as it contains harmful bacteria and viruses. Do not run any water down drains or flush toilets, as this will add to the problem. If you know the location of your main home sewer cleanout, you may carefully open it to relieve pressure, but be prepared for a release of sewage.
Then, contact a plumber to address the blockage and local water damage pros for the essential cleanup. The pros have the equipment and training to safely extract the hazardous water, sanitize the affected areas, and begin drying. Keep children and pets away from the area, and do not attempt to clean it with a standard wet vacuum or mop.
Preventing Future Sewer Backups
Long-term prevention focuses on managing what goes into your drains and maintaining your private line. Never pour fats or grease down sinks, and only flush human waste and toilet paper. Consider having a plumber perform a video camera inspection of your sewer line to identify roots, cracks, or bellies. Installing a backwater valve on your main sewer line can provide a mechanical barrier to prevent reverse flow during a public sewer overload.
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Call (405) 565-9833 any time, day or night, and describe what happened.
Call Now (405) 565-9833Frequently asked questions
Is the sewage backup water dangerous?
Yes, it is considered Category 3 black water, containing pathogens, chemicals, and other hazards. Direct contact poses serious health risks. Always treat it as hazardous and rely on professionals for proper cleanup and disinfection.
Will my homeowner's insurance cover this damage?
Coverage depends entirely on your specific policy and the cause. Damage from water entering from outside may have different rules than a drain backup. Policies vary, and your insurer decides what is covered.
Who is responsible for fixing the backup?
You are typically responsible for the sewer line from your house to the connection with the public main, including any clogs there. The city manages blockages in the main public sewer line. A plumber can help determine the location.