Sewage Backup in Your House? What to Do Right Now
Sewage coming through a toilet, floor drain, shower, sink, or other drain is different from an ordinary clean-water leak. Wastewater can contain harmful microorganisms and other contaminants, so avoiding unnecessary contact and identifying the cause are important first steps.
What causes sewage to back up into a house?
A backup means wastewater is not moving through the drainage system as intended. The problem may be inside the home's plumbing, farther down the sewer lateral, in a septic system, or within a larger municipal sewer system.
Blocked Drain or Sewer Line
A blockage can prevent wastewater from moving away from the home and cause it to return through a lower drain, toilet, shower, or other fixture.
Damaged Sewer Line
Broken, collapsed, deteriorated, displaced, or otherwise damaged sewer piping can interfere with normal wastewater flow.
Tree Roots
Roots can enter vulnerable sewer piping through joints, cracks, or damaged sections and contribute to restricted flow or blockage.
Heavy Rain or System Overload
Severe weather, groundwater infiltration, and overloaded sewer systems can contribute to sewer overflows and backups in some circumstances.
Septic System Problem
A full, damaged, flooded, or malfunctioning septic system can interfere with wastewater leaving the home and may cause slow drains or backups.
Municipal Sewer Problem
Problems in a public sewer system can sometimes affect multiple properties. The appropriate utility or local authority may need to determine whether the issue extends beyond the home's private plumbing.
What should you do after a sewage backup?
Treat a sewage backup differently from a small leak involving water from a known clean supply source. The immediate concern is not simply removing visible water. Contact with wastewater and contaminated materials also has to be considered.
- Keep children and pets completely away from the affected area.
- Avoid direct skin contact with sewage and contaminated water.
- Stop unnecessary use of toilets, sinks, showers, washing machines, and dishwashers while the drainage problem is unresolved.
- Do not enter standing water when electrical hazards may be present.
- Document visible damage from a safe location when possible.
- Determine whether the problem appears limited to one fixture or affects multiple drains.
- Arrange for the underlying plumbing, sewer, or septic problem to be identified and corrected.
Sewage-contaminated water can expose occupants to microorganisms and other contaminants. Porous materials contaminated by sewage may not be suitable for ordinary surface cleaning, and professional remediation may be appropriate.
Should you keep using the toilets and sinks?
If the drainage system is backing up, continuing to add wastewater can worsen some problems. Until the cause is understood, reducing unnecessary water use can help avoid sending additional water into a system that may already be blocked or overwhelmed.
What if sewage is coming through a basement floor drain?
Lower-level drains can become points where wastewater appears when a downstream sewer line cannot carry flow normally. A basement backup may therefore be related to a blockage, sewer-line problem, heavy rain, municipal sewer condition, or septic-system issue.
If what you are seeing appears to be ordinary groundwater or rainwater rather than wastewater, our water in basement guide covers those causes separately.
What if only one toilet is backing up?
A problem affecting a single fixture can sometimes indicate a more localized obstruction, while several fixtures backing up or draining slowly can suggest a problem farther along the drainage system. The pattern is useful information for a plumbing professional, but it does not by itself establish the exact cause.
Signs of a possible sewer or drain problem
Some sewer problems provide warning signs before a major backup occurs. Paying attention to patterns across several fixtures can help identify when the problem may extend beyond one clogged sink or toilet.
Multiple slow or backed-up drains
Several fixtures having drainage problems at the same time may indicate a restriction farther downstream in the drainage system.
Gurgling sounds
Unusual gurgling from toilets or drains when other plumbing fixtures are used can be a clue that drainage or venting is not functioning normally.
Water from a floor drain
Wastewater appearing at a basement or lower-level floor drain can indicate that water is backing up through the drainage system.
Sewage odor
Persistent sewer odors can indicate a drainage, trap, vent, sewer, or septic problem that deserves investigation.
Toilet behavior changes
Toilets that drain slowly, bubble, gurgle, or react when other fixtures are used can provide clues about the drainage system.
Problems after heavy rain
Backups associated with major rainfall may point toward saturated septic conditions, infiltration, or an overloaded sewer system.
How is sewage backup damage cleaned up?
Cleanup begins only after the area can be approached safely and the underlying sewage or drainage problem is being addressed. Sewage can contaminate both the standing water and materials it touches.
CDC guidance for sewage cleanup calls for protective measures such as rubber boots, rubber gloves, and goggles. Materials and surfaces also need to be evaluated according to whether they can actually be cleaned and dried safely.
What happens to carpet, drywall, and insulation?
Porous materials can absorb contaminated water. CDC guidance specifically advises discarding drywall and insulation contaminated with sewage or floodwater and identifies a number of other absorbent household items that may not be suitable for cleaning and reuse.
EPA also recommends using a professional experienced with contaminated water when water or mold damage was caused by sewage or other contaminated water.
Can you clean a sewage backup yourself?
The answer depends on the size and circumstances of the event, but sewage contamination introduces risks that are not present in many ordinary household water leaks. Significant contamination, affected porous building materials, electrical hazards, hidden contamination, or uncertainty about safe remediation are strong reasons to seek qualified professional assistance.
For the broader restoration process, see our water damage cleanup and repair guide.
Does homeowners insurance cover a sewage backup?
Coverage depends on the policy, the cause of the backup, exclusions, endorsements, deductibles, limits, and the circumstances of the loss. Sewer or drain backup coverage may be addressed differently from other forms of household water damage.
Do not assume that a standard homeowners policy automatically covers every sewer or drain backup. Review the actual policy and any applicable endorsements, and contact the insurer when appropriate.
What should you document?
- Where the sewage or wastewater entered the home.
- Which rooms and surfaces were affected.
- Damaged flooring, walls, furniture, and belongings.
- Plumbing or sewer findings about the suspected cause.
- Cleanup, plumbing, remediation, and repair invoices or estimates.
- Communications related to the loss and resulting work.
Continue to our water damage insurance guide for a broader explanation of water-related coverage questions.
Sewage backup FAQ
Is a sewage backup dangerous?
Sewage can contain harmful microorganisms and other contaminants. Direct contact should be avoided, children and pets should be kept away, and electrical or structural hazards must also be considered.
Why is sewage coming up through my basement drain?
Possible causes include a blocked or damaged sewer line, an overloaded sewer system, heavy-rain conditions, or a septic-system problem. The exact cause requires investigation of the drainage system.
Should I flush the toilet if the sewer is backing up?
When a drainage system is actively backing up, adding more wastewater can worsen some situations. Avoid unnecessary plumbing use until the underlying problem has been identified.
Can sewage-soaked carpet be saved?
Sewage can contaminate absorbent materials. CDC cleanup guidance identifies carpeting and carpet padding among materials that may need to be discarded after sewage or floodwater contamination.
Who do you call for a sewage backup?
The appropriate professional depends on the cause and extent of the problem. A plumber or sewer professional may be needed to correct the source, while contaminated-water cleanup may require a restoration or remediation professional. Municipal or septic-system problems can require different contacts.
Does homeowners insurance cover sewer backup cleanup?
It depends on the policy and cause of loss. Sewer or drain backup coverage may require specific coverage or an endorsement, so homeowners should review their own policy rather than assume coverage.
What should you figure out next?
Dealing with sewage or contaminated water in your home?
Sewage contamination, extensive affected areas, contaminated porous materials, hidden moisture, or electrical and structural hazards can require qualified professional assistance.