What to Do During a Sewage Backup

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The first thing to do during a sewage backup is stop adding water: do not flush a toilet, run a faucet, start a washing machine, or run a dishwasher anywhere in the house. Every gallon you send down a drain has nowhere to go and pushes more contaminated water up into your living space. The second thing is to treat what came up as a biohazard, not a mess to mop. Raw sewage carries disease-causing organisms, and the way you respond in the first few minutes affects both how much damage you take and whether anyone gets sick.

This guide covers the active emergency response and the safety protocol only. It does not cover what caused the backup or how to prevent the next one. If you want to understand why a line backs up, see our guide on what causes sewer line backups (079). If you are trying to read the early warning signs before a backup happens, see our guide on the signs of a sewer line problem (078). Right now, the priority is people, then containment, then documentation.

Stop the Flow: Why You Must Quit Running Water Immediately

Before anything else, stop sending water into the drain system. A sewage backup means wastewater cannot leave the house through its normal path, so anything you drain has to surface somewhere, usually at the lowest fixture or floor drain. Flushing a toilet on an upper floor can push more sewage into a basement. Running the kitchen sink while the line is blocked does the same thing.

Tell everyone in the home to stop using water entirely. That includes toilets, sinks, showers, tubs, the washing machine, the dishwasher, and any appliance with a drain hose. Turn off an ice maker if it cycles on its own. The goal is to hold the volume of contaminated water at whatever already escaped instead of feeding the problem.

If the backup is large or rising, shutting off the main water supply to the house removes the temptation and the risk of someone using a fixture out of habit. The procedure for locating and closing the main shutoff differs by home, so see our guide on how to shut off the water to your whole house (131) for the step-by-step. Closing the main stops fresh water from entering fixtures; it does not drain what is already in the pipes, so the no-running-water rule still applies until a professional clears the line.

Treat Sewage as a Biohazard: Keep People and Pets Clear

Sewage is contaminated water, and the correct mental model is biohazard, not housekeeping. According to the CDC, sewage and wastewater contain bacteria, fungi, parasites, and viruses that can cause intestinal, lung, and other infections. The EPA advises avoiding contact with flood water because of elevated contamination associated with raw sewage and other hazardous substances, and notes that early symptoms from exposure can include an upset stomach, intestinal problems, headache, and other flu-like discomfort.

Keep children and pets out of the affected area completely. They are lower to the ground, more likely to touch surfaces and then their mouths, and harder to decontaminate afterward. Close off the room if you can.

If you must enter the area at all, even briefly, do not eat, drink, or smoke there, and wash your hands thoroughly before you do any of those things afterward. The CDC’s guidance for people handling human waste is direct on this point. Cover any open cut or sore before exposure, and if a wound does contact sewage, clean and treat it right away, because broken skin is a direct route for infection. If you feel sick after exposure, contact a medical professional.

When (and When Not) to Cut Power to the Affected Area

Cut power to a flooded area only if you can reach the breaker without standing in water or touching anything wet. Water and electricity together can be lethal, and a sewage backup that reaches outlets, cords, or appliances can energize the water around them.

Ready.gov is explicit: do not touch electrical equipment if it is wet or if you are standing in water, and turn off the electricity only if it is safe to do so. In practice that means if your electrical panel is in a dry location you can reach without wading through the backup, you can switch off the circuits feeding the affected area. If reaching the panel means stepping into standing water, do not do it. Stay out, keep others out, and call a professional or your utility to cut power safely.

The same caution applies to unplugging anything. If an appliance or cord is sitting in or near the contaminated water, leave it alone. Do not wade in to rescue belongings or to reach a switch. No possession is worth an electrocution risk, and the water can be charged even if nothing looks wrong.

Ventilate Without Putting Yourself at Risk

Open windows and exterior doors near the affected area to move air through it, which helps with both odor and the buildup of gases that come off sewage. Fresh air exchange is a reasonable step as long as reaching the windows does not require entering the contaminated water or touching anything electrical.

Do not run your central HVAC system if the backup is near return vents or ductwork, because moving that air can spread contamination and odor through the rest of the house. If you are smelling persistent sewer gas in the home apart from the backup itself, that is a separate venting issue covered in our guide on what sewer gas is and why you smell it (152). For the active emergency, simple cross-ventilation with outside air is the safe move, and a professional crew will handle controlled drying and air scrubbing later.

Document Everything for Your Insurance Claim

Photograph and video the damage before anyone touches or removes anything. A clear visual record of how far the water spread, what it reached, and the condition of affected belongings is the foundation of an insurance claim, and it is far easier to capture now than to reconstruct later.

Work through the space methodically. Capture wide shots that show the extent of the flooding and close shots of damaged flooring, walls, furniture, and any standing water line on the wall. Note the date and time. Keep any receipts for emergency services, temporary lodging, or supplies you buy in response.

Coverage for sewage and water backup is not automatic. Many standard homeowners policies treat sewer or drain backup as a separate add-on rather than a default inclusion, so contact your insurer early to report the loss and ask exactly what your policy covers and what documentation it requires. Ask before you discard contaminated materials, since some insurers want to inspect or want specific proof first. Verify your own coverage and claim steps directly with your insurance company, because policies and requirements vary.

What a Licensed Plumber and Restoration Crew Will Do

A licensed plumber clears the blockage or repairs the failed line, and a certified restoration company handles the contaminated cleanup, drying, and disinfection. These are two different jobs, and a significant sewage backup usually needs both.

The plumber’s role is to find and remove the cause so wastewater can leave the house again. That can mean augering or jetting the line, running a camera to locate a break, or repairing or replacing damaged pipe. None of that is homeowner work when sewage is actively backing up, and a collapsed or offset line is excavation territory rather than a do-it-yourself fix.

The restoration crew handles the biohazard side: extracting contaminated water, removing and discarding porous materials that cannot be disinfected, cleaning and disinfecting surfaces with appropriate products, and drying the structure. Timing matters here. The CDC and EPA both note that wet materials should be dried within roughly 24 to 48 hours when possible, because mold can take hold quickly on materials that stay damp. The mechanism by which lingering moisture turns into a mold problem is covered separately in our guide on how plumbing leaks lead to mold (155); during the emergency, the takeaway is simply that fast, professional drying limits the secondary damage.

What You Should Never Try to Clean Up Yourself

Do not attempt the cleanup of a significant sewage backup yourself. The EPA states plainly that if water or mold damage was caused by sewage or other contaminated water, you should call in a professional who has experience cleaning and fixing buildings damaged by contaminated water, and that you should not attempt a mold cleanup yourself if the mold was caused by contaminated water.

Two categories of material generally cannot be salvaged after sewage contact and have to be discarded. Porous items that soak up contaminated water, such as carpet and padding, mattresses, upholstered furniture, and many fabrics, are very difficult to fully disinfect. The CDC also advises removing and discarding drywall and insulation that has been contaminated with sewage or flood water. Hard, non-porous surfaces like sealed concrete, tile, metal, and glass can often be cleaned and disinfected, which is part of why this is professional judgment rather than a guessing game.

If circumstances force you to be near the area at all before help arrives, the CDC’s minimum protective equipment for this kind of cleanup is goggles, an N-95 respirator, and protective gloves, plus rubber boots and rubber gloves when sewage is involved. Even with that gear, the safe default for a meaningful backup is to stay out, keep the area sealed off, and let trained crews with the right equipment do the work. The point is not to tough it out; it is to avoid turning a property loss into an illness or injury.

Frequently Asked Questions

What is the very first thing to do during a sewage backup?
Stop running water immediately. Do not flush toilets or use any sink, shower, washing machine, or dishwasher in the house. With the drain line blocked, every gallon you send down has nowhere to go and pushes more sewage up into the home. After that, keep people and pets away from the contaminated water and treat it as a biohazard.

Can I clean up a sewage backup myself?
For a significant backup, no. Sewage carries bacteria, viruses, and parasites, and federal guidance from the EPA is to call a professional experienced with contaminated water rather than attempt the cleanup yourself. Porous materials soaked with sewage, like carpet, padding, and contaminated drywall, usually have to be discarded, while a certified restoration crew disinfects and dries what can be saved.

Should I turn off the electricity during a sewage backup?
Only if you can reach the breaker panel without standing in water or touching anything wet. Sewage that reaches outlets or appliances can energize the water, which is potentially deadly. Federal safety guidance says not to touch electrical equipment if it is wet or if you are standing in water, and to cut power only when it is safe to do so. If the panel is in the flooded area, stay out and call a professional or your utility.

Is sewage backup water actually dangerous, or just gross?
It is genuinely dangerous. The CDC notes that sewage contains bacteria, fungi, parasites, and viruses that can cause intestinal, lung, and other infections, and the EPA warns that exposure can cause stomach upset, intestinal problems, headache, and flu-like symptoms. Avoid contact, keep cuts covered, do not eat or drink in the area, and wash thoroughly afterward.

Will my homeowners insurance cover a sewage backup?
It depends on your policy. Water or sewer backup coverage is often a separate add-on rather than part of a standard homeowners policy, so it is not guaranteed. Photograph and video everything before cleanup begins, save related receipts, and contact your insurer early to confirm what is covered and what documentation they need before you discard contaminated materials.

This is general information, not professional advice. A sewage backup involves contaminated water and serious health and electrical hazards, so call a licensed plumber and a certified restoration company for any meaningful backup, and do not attempt cleanup of significant contaminated material yourself.

Sources

CDC, Guidelines for Cleaning Safely After a Disaster (Natural Disasters): https://www.cdc.gov/natural-disasters/safety/index.html
CDC, Protecting Workers Handling Human Waste (Global WASH): https://www.cdc.gov/global-water-sanitation-hygiene/about/workers_handlingwaste.html
CDC, Homeowners and Renters Guide to Mold Cleanup After Disasters: https://www.cdc.gov/mold-health/communication-resources/guide-to-mold-cleanup.html
EPA, Flood Cleanup to Protect Indoor Air and Your Health: https://www.epa.gov/emergencies-iaq/flood-cleanup-protect-indoor-air-and-your-health
EPA, Mold Cleanup in Your Home: https://www.epa.gov/mold/mold-cleanup-your-home
Ready.gov, Floods (electrical safety during flooding): https://www.ready.gov/floods

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