Short answer
With a sewage backup, protect people first. Keep children and pets out, stop using water, and switch off power only if you can do it from a dry spot. Then call a plumber, ask your city or sewer utility whether the main may be blocked, and tell your insurer before cleanup. Photograph everything. Wear rubber boots, gloves and eye protection for any contact.
Do this first
- Get people out of the affected area. Keep children and pets away. If you smell gas, leave the house and call the gas company or emergency services from outside. Do not use switches or anything that could spark.
- Stop adding water to the drains. Do not flush toilets, run showers, or use the washing machine or dishwasher. Water you send down can come back up in the basement. If a fixture is running, shut it off.
- Do not step into standing water near outlets, appliances or the electrical panel. The CDC says to turn off power at the main breaker only if you can reach it without entering the water, and to call an electrician if you cannot.
- Do not try to plug a floor drain to stop sewage coming up. The City of Northville, Michigan warns that an added obstruction can damage the household drainage system.
- Take photos and video before you move or touch anything.
- Call a licensed plumber, and call your city or sewer utility if the main may be involved (details below).
- Call your insurer before cleanup starts, and keep every receipt.
- Only then clean up, and only the parts that are safe for you to do (see below).
This is general information from public health and utility sources, not a substitute for your local health department, utility or insurer.
What is a sewage backup and why does it happen
A sewage backup, sometimes called a sewer line backup or a sewer backup in the basement, means wastewater comes up through a floor drain, toilet, tub or sink instead of flowing out to the main. Seattle Public Utilities says backups usually happen when something blocks the sewer pipe and stops wastewater flowing freely. Its handout names tree roots, grease and flushed objects such as wipes as common reasons.
The blockage may be in a fixture drain, in your private line to the street, or in the public main. The City of Northville says most backups come from problems in the home plumbing or the private line, and only rarely from the public line. To understand which pipe is whose, see main sewer line location: how to find yours and sewer cleanout and sewer cleaning explained.
Health risks of a sewage backup
Treat sewage as a health hazard, not just a mess. Colorado's public health department, in its homeowner guidance on cleaning up after sewer backups (2011), says untreated sewage contains disease-causing organisms such as bacteria, viruses and parasites. It says skin contact can cause infections and rashes, accidental swallowing through unwashed hands or food surfaces can cause nausea, abdominal pain, vomiting and diarrhea, and breathing in airborne microorganisms can cause respiratory infections and allergic reactions.
The CDC's guide to cleaning safely after a disaster says floodwater can carry dangerous bacteria and that skin contact alone is not a serious risk, but eating or drinking contaminated items can make you sick. The City of Northville adds that germs spread by touching contaminated items or by tracking them on shoes, and that children and pets are especially vulnerable. Both Northville and the City of Livonia, Michigan advise keeping cuts and sores clean and covered, and asking a doctor or the health department about a tetanus shot if you cut yourself during cleanup.
Who to call after a sewer backup, and in what order
The right order depends on what you see, but most homes can follow this sequence quickly.
| Call | When | What to ask |
|---|---|---|
| Emergency services or the gas company | You smell gas, see sparking, or fear an electrical hazard | Leave first, call from outside |
| An electrician | You cannot reach the panel without entering water | Power shut-off and inspection before restoring power |
| A licensed plumber | Almost always | Cause, location, a written scope, and a copy of any camera video |
| City public works or your sewer utility | Several homes affected, no water running yet backups continue, or you suspect the main | Whether the main is blocked, and the claim process if one exists |
| Your insurer or agent | Before cleanup begins | What they need: photos, a list of items, receipts |
| County health department | Cleanup questions, exposure concerns, sewage in the yard | Local cleanup guidance |
Seattle Public Utilities lists the steps as: protect people and turn off power, call a plumber, call the utility, document damage and keep invoices, then clean up. The City of Livonia says a city crew will check whether the backup is in the city main or your private line. If the main is clear, you hire a licensed plumber or drain service. Livonia says to get several estimates and check references. For help vetting a company, see drain cleaning near me: how to find and vet a company.
One more caution from Seattle Public Utilities: before attempting to clear a blockage in your private line, call the gas utility so you do not damage a gas line. Ask your plumber whether that applies where you live.
Protective gear and hygiene
For sewage the CDC recommends rubber boots, rubber gloves and goggles. Northville adds protective clothing, and recommends removing gloves by turning them inside out without touching the dirty outside, then disposing of them properly. Colorado's bulletin adds a dust mask when cleaning to avoid breathing airborne microorganisms.
- Wash your hands often, especially before eating. Do not eat or drink anything that touched sewer water, and keep contaminated hands away from your mouth, eyes and nose.
- The CDC says to wash cleanup clothes in hot water with detergent, separate from clean laundry.
- Never mix bleach with ammonia. Colorado, Northville, Livonia and the CDC all warn about this, because the mix makes toxic gas.
What you can and cannot clean yourself
Hard, non-porous surfaces can often be cleaned and disinfected by the household. Porous materials soak sewage up and are very hard to make safe. The CDC's list of things to discard includes mattresses, carpeting and padding, rugs, upholstered furniture, stuffed animals, baby toys, pillows, foam rubber, books and paper products, plus drywall and insulation contaminated with sewage.
| Item | General guidance |
|---|---|
| Concrete floors and walls | Colorado says wash thoroughly and let dry out |
| Tile, vinyl, sealed hard floors, counters, fixtures | Washington State's health department says wash with hot water and dish detergent, rinse with a bleach solution, then let air dry |
| Wall-to-wall carpet and pad | Washington says it usually cannot be cleaned adequately; Livonia says soaked pad should be thrown out |
| Soft or soaked drywall and insulation | Colorado says consider removing and replacing; Northville says remove wet drywall within 24 hours |
| Upholstered furniture, mattresses, stuffed toys | Generally discard; some valued pieces can go to a professional cleaner |
| Furnace, ductwork, wet motors or wiring | Northville says have a qualified technician inspect before turning back on |
Keep a list of discarded items and photograph them before they go.
Drying and disinfection basics
Speed matters, but so does doing it in a safe order: remove standing sewage, remove what cannot be saved, clean, then disinfect and dry. The CDC advises cleaning and drying within 24 to 48 hours when possible, and the EPA says the same window helps prevent mold in water-damaged areas. The EPA also says that if the damage came from sewage, you should call in a professional. Colorado warns that drying a basement can take several weeks.
- Clean before disinfecting. Wash with hot water and detergent first, then disinfect.
- Open the area up. Open windows and doors. Colorado says fans and dehumidifiers can circulate air, but furnace blowers and whole-house air conditioning should only run if the ducts were not touched by wastewater. Other guidance cautions against fans until you know the water is clean, so ask a professional or your health department.
- Do not use heat to dry a closed-up interior. Northville warns that mildew and more water damage may result.
- Flush and disinfect plumbing fixtures after the water recedes, before normal use (Northville).
| Source | Solution given |
|---|---|
| Colorado Dept. of Public Health and Environment (2011) | One-quarter cup bleach per gallon of water, in contact for at least one minute, then rinse |
| City of Northville and City of Livonia, Michigan | Eight tablespoons of bleach per gallon of water |
| Washington State Department of Health | One tablespoon of unscented bleach per gallon of water, as a rinse after detergent cleaning |
The spread is large, so confirm with your local health department.
When to leave cleanup to professionals
The City of Northville recommends a thorough professional sanitized cleanup. The City of Chilton, Wisconsin calls a professional restoration company the best way to deal with a sewage backup in the basement. The EPA says to call a professional when damage comes from sewage. Consider that route if:
- The affected area is large, or sewage reached walls, insulation or flooring you cannot easily remove.
- Ductwork, a furnace, a water heater or other equipment was touched.
- You cannot keep children or pets away from the area.
- You are unsure about electrical or gas hazards. Call the utility or emergency services for those.
Whoever does the work, ask for a written scope and keep invoices.
Insurance, photos and city claims
Insurance rules differ widely, so this page does not say what any policy covers. Call your insurer before cleanup and ask what they require. In general:
- Take before and after photos, keep a list of discarded items with photos, and keep receipts for cleaning, plumbing and restoration (Northville and Livonia both advise this).
- If the backup might be a public sewer problem, ask the city about its claim process right away. Livonia and Northville both say a written claim must be filed within 45 days and that the claimant must show a defect in the public sewer, under Michigan law. Other places differ.
Preventing a sewer line backup
- Keep grease, wipes, paper towels and sanitary products out of drains. Northville and Seattle Public Utilities both list these as common causes.
- Know where your cleanout is and keep it accessible, as Northville advises.
- Ask a plumber about a backflow valve on the lowest drain (Northville and Chilton both mention it) and about periodic cleaning of the private line.
- Get a camera look after a blockage is cleared. Seattle Public Utilities says a camera cannot see under water, so inspection helps most after the line is clear. Ask for a copy of the video.
- Check for roots if backups return: tree roots in sewer lines.
If gurgling or slow drains come first, read gurgling drains and toilets and clogged drain: what to try yourself and when to call a plumber. If you are on a septic system, the cause may be the tank or drainfield. Call a septic professional and your county health department, and see septic pumping near me and signs your septic system is failing.
What to look up where you live
- Your city public works or sewer district: who owns which part of the line, the emergency number, and whether there is a claim process with a deadline.
- County health department or environmental health office: local cleanup guidance and what to do about sewage in the yard.
- State or provincial plumbing or contractor licensing board: to confirm a plumber's licence and check complaints.
- Your insurance agent: what your policy says about sewer backup and what they need from you.
For Canadian readers. Plumbing is regulated by each province or territory, and municipalities set their own rules for sewer connections and backups. Check your provincial regulator and your city. Costs are in Canadian dollars and cannot be compared directly with US figures.
For plumbing, drain and septic company owners
A sewage backup is the call that cannot wait, and your customers search for it in the middle of the night. If you want to be the company that picks up and gets found, read emergency plumber marketing and plumbing answering service. You can also book a call with LiveLeadsLane. LiveLeadsLane is a marketing practice for contractors, not a directory, and it does not take jobs or refer homeowners.
