Sewage Backup in Your Home: What to Do and Avoid

Arko Smygov
Co-owner, Pyper Plumbing · Published October 11, 2026 · 6 min read

Quick answer

Stop using all water and do not flush. Keep people and pets away from the sewage, and turn off power to any area where it has reached outlets or standing water. Do not pour chemical drain openers into the backup. Call a plumber, and call your sewer utility if you think the city main is involved.

Step 1: Stop adding water to the system

Every toilet flush, shower, load of laundry or dishwasher cycle sends more water into a line that is already blocked. Stop all of it. The City of Anacortes tells residents to stop using toilets, sinks, showers, dishwashers and laundry machines during a backup, and Seattle Public Utilities says to avoid flushing toilets or running water while sewage is backing up.

Tell everyone in the household, including guests. Put a note on the toilets if needed. Do not try to stop sewage from rising through a drain.

Step 2: Protect people and pets

Sewage carries germs that can make people sick. Keep children and pets out of the affected area. The City of Anacortes advises that people with young children, older adults, pregnant people, or anyone with a respiratory condition or weakened immune system consider leaving if the backup cannot be isolated.

If you must enter the area, follow the protective steps Seattle Public Utilities recommends.

Wear long sleeves, long pants, rubber boots, rubber gloves and eye protection.
Keep sewage away from your mouth, eyes, nose, cuts and sores. Cover and clean any wounds.
Do not eat or drink anything that sewage touched.
Wash hands thoroughly afterward. Wash contaminated clothes and shoes separately from other laundry.
If you cut yourself in sewage, ask a doctor about a tetanus shot.
See a doctor promptly if you develop nausea, vomiting or diarrhea after exposure.

Step 3: Handle electrical and heating equipment carefully

Do not use electrical equipment while standing in water. Seattle Public Utilities recommends shutting off power to the affected area and unplugging appliances, and turning off gas or other fuel to a furnace, heater or water heater if they were reached by water. The City of Anacortes adds that forced-air furnaces and air conditioners should be turned off if sewage has entered the ductwork.

If the breaker panel is in a wet area, do not go near it. Call your electric utility or 911. Pyper does not do electrical or gas work, so any wet wiring, panel or gas appliance needs a licensed electrician or your gas utility. If you smell gas, leave and call 911.

Step 4: Work out whether it is one drain or the main line

The location of the problem decides who fixes it. There is no home test that is certain, and city crews are the ones who determine the source. The City of Minneapolis, for example, states that a crew assesses the property to determine whether the blockage is in the city pipe or the private lateral. Still, a few clues help you describe the problem when you call.

A clog in one fixture, such as a single toilet that will not flush while everything else drains normally, is usually in that fixture's own drain line. Slow drains or gurgling across several fixtures, or sewage appearing at the lowest drain in the house (a basement floor drain or a ground-floor tub), points toward the main drain or the lateral that runs to the street. Plumbers generally look at the lowest drain first because that is where backed-up sewage emerges.

Neighbors matter too. Minneapolis notes that if neighbors have similar slow drains, the city pipe may be the cause. Ask next door, and call your sewer utility if others are affected.

One fixture affected, others fine: likely a local fixture or branch clog.
Several fixtures slow, gurgling, or a low drain backing up: likely the main drain, lateral or city main.
Neighbors with the same problem: report it to your sewer utility right away.

Step 5: Do not use chemical drain openers

It is tempting to pour in a drain opener. Do not do it on a sewage backup. Standing sewage will not let the product work as intended, and the caustic liquid stays in the pipe and the standing water where it can splash onto you or onto the plumber who comes to clear the line. Sewage is already hazardous, and adding a corrosive makes a spill or splash worse.

MedlinePlus lists common drain cleaner ingredients, including hydrochloric acid, lye (sodium hydroxide), potassium hydroxide and sulfuric acid, and says exposure can cause burns to the skin, eyes, mouth, throat and airways, and breathing trouble. Never mix cleaning products either. Seattle Public Utilities warns that bleach and ammonia produce toxic fumes.

If someone is splashed, flush skin or eyes with water for at least 15 minutes and call Poison Help at 1-800-222-1222 or 911.

Step 6: Notify the right people

If you think the city main is involved, or you cannot tell, call your sewer utility or public works department. The City of Anacortes says to call Public Works for a suspected main line obstruction, and for a lateral or unknown location, to have Public Works check the main and then hire a sewer contractor. After hours, their guidance is to call 911. In Seattle, mainline problems go to Seattle Public Utilities.

Who pays depends on where the failure is. Anacortes states that property owners maintain the lateral line and are responsible for damage from obstructions on their portion, while the city maintains the main and may be responsible only if negligent. Local rules differ, so check with your own city or sewer district.

Then call your insurance company. Some policies cover sewer backup and others do not, and coverage often depends on an endorsement. Take photos before and after cleanup, photograph items before discarding them, list damaged items, and keep receipts. The City of Anacortes advises checking with your adjuster before throwing anything away, and not delaying cleanup while a claim is pending, because delay often causes more damage.

Cleanup: small spills versus a professional job

Small, contained backups, such as a bathroom floor, can be cleaned by the homeowner using the protective gear above. Larger backups, backups into carpet or walls, or any sewage that reached ductwork should go to a professional cleaning or restoration company.

Basic guidance from the City of Anacortes and Seattle Public Utilities:

Remove standing water and solid waste. Use a wet vacuum only on a GFCI outlet.
Discard porous items sewage touched, such as carpet, mattresses, upholstered furniture, food, medicines and cosmetics.
Wash hard surfaces with detergent and hot water first, then disinfect. Seattle lists about eight tablespoons of bleach per gallon of water, and Anacortes lists a 1 to 10 bleach and water mix left on for 15 to 20 minutes. Follow your local guidance.
Remove or sanitize wallboard and wall coverings within 24 hours, and cut wallboard out several inches above the water line if needed.
Dry the space with fans, dehumidifiers and open windows once the sewage is removed.
Have a qualified technician check motors, wiring and appliances before using them again.

What a plumber does once you call

A plumber typically clears the blockage from a cleanout or another access point and then inspects the line, often with a camera, to find the cause. Causes can include roots, a broken or offset pipe section, buildup, or a collapsed line. If the pipe is damaged, clearing it only restores flow for a while, so the camera inspection tells you whether a repair or replacement is needed.

Ask for the findings in writing or on video, because your insurer or city may want them.

When to call Pyper Plumbing

Call us when sewage is backing up, several fixtures are affected, or a drain keeps returning after being cleared. Pyper Plumbing provides drain cleaning and sewer line repair for homes in Snohomish, Skagit, Whatcom and Island counties.

Two limits to know. If your home is on a septic system, call a septic professional, since Pyper does not do septic work. And Pyper does not clean up or restore sewage damage inside the home, so plan for a cleanup or restoration company separately. We can tell you honestly which problem you have and who should handle each part.

Common questions

Can I use drain cleaner on a sewage backup?

No. Chemical drain openers are corrosive, can splash back during later work, and will not reliably clear a blocked sewer line. Call a plumber instead, and call Poison Help at 1-800-222-1222 if anyone is exposed.

How do I know if the backup is the main sewer line?

Several fixtures slowing or gurgling, sewage at the lowest drain in the house, or neighbors with the same problem suggest the main line or lateral. A plumber or your sewer utility can confirm the location.

Who is responsible for a sewer backup, me or the city?

It depends on where the blockage is. In general, owners maintain the private lateral and cities maintain the public main, but rules differ by city. Call your sewer utility to find out.

Is sewage cleanup something I can do myself?

Small, contained spills can be handled with gloves, boots, eye protection and proper disinfecting. Larger spills, sewage in carpet or walls, or any in ductwork are best left to a professional cleaning company.

Sources

Facts in this guide come from the following references. Local rules and manufacturer instructions can differ, so follow your utility and your equipment manual.

This guide is general information, not a substitute for an on-site inspection. If you smell natural gas, leave the building and call 911 or your gas utility. Pyper does not perform gas line work.

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