How to Clean Up a Sewage Backup: Step-by-Step Safety Guide

A sewageSewage is wastewater containing biological and chemical cont... More backup is one of the most hazardous situations a homeowner can face. Raw sewageSewage is wastewater containing biological and chemical cont... More contains human waste, pathogensPathogens are microorganisms such as bacteria, viruses, or f... More, bacteria, and virusesViruses are microscopic infectious agents that can only repr... More that pose serious health risks, and the longer contaminated water sits in your home, the worse the structural damage becomes.

This guide walks you through exactly what to do after a sewageSewage is wastewater containing biological and chemical cont... More backup, step by step, including when to attempt cleanup yourself and when to call a professional restorationRestoration is the process of returning a property to its pr... More company. RestorationMaster technicians have responded to thousands of sewageSewage is wastewater containing biological and chemical cont... More backup emergencies. The guidance below reflects the same protocols our IICRC-certified crews follow on every job.

Important: DIY sewageSewage is wastewater containing biological and chemical cont... More cleanup is only appropriate for minor, contained spills in a single room. Any backup that has spread across multiple rooms, been sitting for more than 24 hours, or originated from a septic tank or main sewer line requires professional remediation.

Key Takeaways: Sewage Cleanup

• SewageSewage is wastewater containing biological and chemical cont... More backup is Category 3 water damage — remove all porousPorous describes a material that contains small openings or ... More materials, do not clean them.
• Wear an N95 respirator, nitrile gloves, rubber boots, coveralls, and sealed goggles.
• Use a HEPA-filtered vacuum or submersible pump to remove standing water.
• Dry the area within 24 to 48 hours to prevent moldMold is a type of fungus that grows in damp or humid conditi... More growth.
• DIY cleanup only applies to minor, contained, single-room spills.
• Never run HVAC or ceiling fans before the area is decontaminated.
• SewageSewage is wastewater containing biological and chemical cont... More odorAn odor is a smell, often detectable by the human nose, whic... More after 48 hours means hidden contaminationContamination is the presence of harmful or unwanted substan... More remains.

What is Sewage?

SewageSewage is wastewater containing biological and chemical cont... More is wastewaterWastewater is used water that contains contaminants, chemica... More generated from toilets, sinks, showers, washing machines, and dishwashers in homes and businesses. While sewageSewage is wastewater containing biological and chemical cont... More is primarily water, it carries a mixture of human waste, urine, bacteria, virusesViruses are microscopic infectious agents that can only repr... More, parasites, chemicals, and soaps that make it a serious biohazard.

Under IICRC S500 standards, the water damage restorationWater damage restoration is the professional process of clea... More industry classifies sewageSewage is wastewater containing biological and chemical cont... More backup as Category 3 water damage, the most contaminated and dangerous classification. This matters because it directly determines the cleanup protocol: all porousPorous describes a material that contains small openings or ... More materials that come in contact with Category 3 water must be removed and discarded, not simply dried or cleaned.

Types of Sewage

• Blackwater: WastewaterWastewater is used water that contains contaminants, chemica... More from toilets. Contains human waste, urine, and the highest concentration of pathogensPathogens are microorganisms such as bacteria, viruses, or f... More. Always classified as Category 3 water damage. Requires full protective gear and professional-grade disinfectants.
• Greywater: WastewaterWastewater is used water that contains contaminants, chemica... More from sinks, showers, and washing machines. Lower pathogen load than blackwater, but still contains contaminants, including soap, grease, and chemicals. Can degrade to Category 3 if left standing for more than 24 hours.

What Should I Do After Sewage Backup?

Before any cleanup begins, take the following precautions. Do not skip these steps, even if the spill appears minor.

• Evacuate children, elderly family members, and pets from the affected area immediately. Do not allow them back until the area is fully cleaned and cleared.
• Shut off electricity and gas to the affected area. Contact your utility company or turn off the breaker yourself, but only if the panel is located safely above the water line. Never step through standing water to reach an electrical panel.
• Turn off the water supply to prevent additional sewageSewage is wastewater containing biological and chemical cont... More from entering the space.
• Open windows to ventilate the affected area and reduce airborne contaminants.
• Close interior doors between the contaminated area and the rest of the home to limit the spread of sewage-contaminated air and debris.
• Do not attempt to unclogTo unclog is to clear obstructions from pipes, drains, or eq... More drains. The sewageSewage is wastewater containing biological and chemical cont... More water must be fully removed before addressing the underlying cause.
• Move dry, uncontaminated items out of the area if you can do so without entering the contaminated zone.
• Add small amounts of diluted chlorine bleach to standing water if you are unable to remove it immediately. This limits bacterial growth while you wait for extraction.
• Contact your homeowners’ insurance company. Document the damage thoroughly with photos and video before cleanup begins. You will need this for your insurance claim.

Read: Why Sewage Backup Should Be Cleaned by Professionals

How to Clean Up a Sewage Backup: Step-by-Step

These steps apply to minor, contained sewageSewage is wastewater containing biological and chemical cont... More spills only. If the backup has spread beyond a single room, originated from a main sewer line or septic system, or has been sitting for more than 24 hours, stop here and call a professional restoration company.

Step 1: Put On the Right Protective Equipment

This is not optional. SewageSewage is wastewater containing biological and chemical cont... More contains pathogensPathogens are microorganisms such as bacteria, viruses, or f... More that cause serious illness, including E. coli, hepatitis A, Salmonella, and leptospirosis. Before entering the affected area, you need:

• N95 or P100 respirator (not a standard dust mask, which does not filter biological particles)
• Nitrile or rubber gloves rated for chemical and biological hazards
• Rubber boots or waterproof shoe covers
• Waterproof coveralls or clothes you are prepared to discard after cleanup
• Safety goggles that seal against your face (standard glasses do not protect against splash exposure)

Do not allow any skin to come into direct contact with sewageSewage is wastewater containing biological and chemical cont... More water or contaminated surfaces.

Step 2: Remove Standing Water and Solid Waste

Remove sewageSewage is wastewater containing biological and chemical cont... More water as quickly as possible. For small volumes, use a wet-dry vacuum equipped with a HEPA filter (standard shop vac filters are not adequate for sewageSewage is wastewater containing biological and chemical cont... More). For larger volumes, use a submersible pump or call a professional for water extraction.

Carefully collect solid waste using disposable tools and place it directly into heavy-duty plastic bags. Double-bag the waste, seal it tightly, and dispose of it immediately. Do not leave bagged sewageSewage is wastewater containing biological and chemical cont... More waste sitting in the affected area.

Step 3: Remove and Discard Contaminated Porous Materials

Under IICRC Category 3 protocol, any porousPorous describes a material that contains small openings or ... More material that has been in contact with sewageSewage is wastewater containing biological and chemical cont... More must be removed and discarded. This includes:

• Carpet, carpet padding, and area rugs
• Drywall and wall paneling (up to at least 12 inches above the water line)
• Flooring underlayment and insulationInsulation is a material used in buildings to reduce the tra... More
• Upholstered furniture and mattresses
• Books, paper products, and cardboard
• Food and consumable goods of any kind

These materials cannot be reliably cleaned and disinfected. Attempting to salvage them creates ongoing moldMold is a type of fungus that grows in damp or humid conditi... More and pathogen risk.

Step 4: Clean and Disinfect All Surfaces

Wash all hard surfaces (walls, floors, baseboards, concrete) with hot water and a bactericidal disinfectantA disinfectant is a chemical substance used to kill or inact... More. Follow this sequenceSequence is the specific order or progression of steps taken... More:

• First pass: scrub with hot water and a quality household detergent to remove physical contaminationContamination is the presence of harmful or unwanted substan... More
• Second pass: disinfect with a solutionA solution is a homogeneous mixture of two or more substance... More of 1 part chlorine bleach to 4 parts water, applied with a stiff brush
• Rinse thoroughly with clean water
• Apply an EPA-registered disinfectant rated for sewageSewage is wastewater containing biological and chemical cont... More or Category 3 water damage for a final pass

Pay extra attention to floor grout, wall corners, and any surfaces that have had prolonged contact with standing water. These areas harbor bacteria even after visible contaminationContamination is the presence of harmful or unwanted substan... More is removed.

Step 5: Dry the Area Completely

After disinfecting, the affected area must be dried completely within 24 to 48 hours to prevent moldMold is a type of fungus that grows in damp or humid conditi... More growth. MoldMold is a type of fungus that grows in damp or humid conditi... More can begin colonizing damp materials in as little as 24 hours following a water intrusion event.

Use a combination of:

• High-volume fans or air movers directed at wet surfaces
• Commercial-grade dehumidifiers (residential units are often insufficient for this level of saturationSaturation is the point at which a material or environment c... More)
• Open windows if the outdoor humidityHumidity is the amount of moisture or water vapor present in... More is lower than the indoor humidityHumidity is the amount of moisture or water vapor present in... More

Monitor moisture levels with a moisture meterA moisture meter is a device used to measure the moisture le... More. Do not close up walls or replace flooring until readings return to normal baseline levels.

Step 6: Clean or Discard Contaminated Items

Non-porous items (hard furniture, appliances, tile surfaces) can be cleaned with an antibacterial disinfectantA disinfectant is a chemical substance used to kill or inact... More, rinsed thoroughly, and allowed to dry completely before reuse.

• For clothing and linens with minor sewageSewage is wastewater containing biological and chemical cont... More contact: Machine wash on the hottest setting appropriate for the fabric, with one cup of chlorine bleach added if the fabric can tolerate it.
• For items with high sentimental or monetary value: Contact a professional contents restorationRestoration is the process of returning a property to its pr... More company before discarding. Specialized cleaning techniques can sometimes salvage items that appear unsalvageableUnsalvageable items or materials are too damaged, contaminat... More.

Step 7: Inspect for Mold

SewageSewage is wastewater containing biological and chemical cont... More backups create ideal conditions for moldMold is a type of fungus that grows in damp or humid conditi... More growth throughout the affected area, including on surfaces that had no direct contact with wastewaterWastewater is used water that contains contaminants, chemica... More. Elevated indoor humidityHumidity is the amount of moisture or water vapor present in... More affects areas well beyond the visible spill zone. After cleanup and dryingDrying is the process of removing moisture from materials, s... More, inspect all surfaces for visible moldMold is a type of fungus that grows in damp or humid conditi... More growth. Pay close attention to wall cavities, behind baseboards, under flooring, and in ceiling spaces above the affected area if water wicked upward.

Use an EPA-approved moldMold is a type of fungus that grows in damp or humid conditi... More cleaner to address any visible moldMold is a type of fungus that grows in damp or humid conditi... More growth. If the affected area is larger than 10 square feet, or if moldMold is a type of fungus that grows in damp or humid conditi... More is present inside walls or ductwork, contact a mold remediationMold remediation is the process of identifying, removing, an... More specialist. Disturbing large moldMold is a type of fungus that grows in damp or humid conditi... More colonies without proper containment spreads sporesSpores are microscopic reproductive units of fungi or mold t... More throughout your home.

What NOT to Do After a Sewage Backup

These common mistakes can make a sewageSewage is wastewater containing biological and chemical cont... More backup significantly worse, create health hazards, or damage your insurance claim.

• Do not run your HVAC system or ceiling fans before the area is decontaminated. Running forced air before cleanup is complete aerosolizes sewage-contaminated particles and spreads them throughout your entire home through the duct system.
• Do not use a standard shop vacuum on sewageSewage is wastewater containing biological and chemical cont... More water. A regular wet-dry vacuum without HEPA filtration will blow contaminated particles into the air. If you do not have a HEPA-filtered unit, use a pump or call a professional for extraction.
• Do not pour undiluted bleach directly onto sewageSewage is wastewater containing biological and chemical cont... More. Undiluted bleach can react with organic waste and produce toxic chlorine gas. Always dilute bleach before use (1 part bleach to 4 parts water).
• Do not delay cleanup. After 24 hours, the bacterial load in sewageSewage is wastewater containing biological and chemical cont... More water increases exponentially. Category 3 water that was manageable at the 2-hour mark becomes significantly more hazardous by the 24-hour mark.
• Do not attempt to clean and keep porousPorous describes a material that contains small openings or ... More materials. Carpet, drywall, and insulationInsulation is a material used in buildings to reduce the tra... More that have absorbed sewageSewage is wastewater containing biological and chemical cont... More cannot be reliably disinfected. Keeping them creates ongoing moldMold is a type of fungus that grows in damp or humid conditi... More and pathogen risk.
• Do not ignore odorAn odor is a smell, often detectable by the human nose, whic... More after cleanup. Persistent sewageSewage is wastewater containing biological and chemical cont... More odorAn odor is a smell, often detectable by the human nose, whic... More after cleanup indicates residual contaminationContamination is the presence of harmful or unwanted substan... More, often in hidden areas like subfloorThe subfloor is the foundational layer beneath flooring mate... More cavities, wall voids, or drain traps. Do not assume the odorAn odor is a smell, often detectable by the human nose, whic... More will dissipate on its own.

How to Get Rid of Sewage Smell After a Backup

Sewage odor after cleanup is caused by two things: residual hydrogen sulfide gas (the primary source of the “rotten egg” smell) and ongoing bacterial activity in contaminated materials that were not fully removed or disinfected.

Surface cleaning alone will not eliminate sewageSewage is wastewater containing biological and chemical cont... More odorAn odor is a smell, often detectable by the human nose, whic... More. To address it properly:

• After disinfecting, apply an EPA-registered odorAn odor is a smell, often detectable by the human nose, whic... More neutralizer (not a maskingMasking is the process of covering or protecting surfaces to... More agent or air freshener, which only cover the smell temporarily)
• Run air scrubbers with HEPA and activated carbon filters, which remove both particulates and odor-causing gases
• Check subfloorThe subfloor is the foundational layer beneath flooring mate... More cavities and wall voids, where contaminated water may have wicked upward into areas that were not cleaned
• Flush all drains in the affected area with a diluted bleach solutionA solution is a homogeneous mixture of two or more substance... More to eliminate odor-causing bacterial buildup in the drain traps
• Replace any drain trap water seals that may have dried out, as empty P-traps allow sewer gas to enter the home directly

If sewageSewage is wastewater containing biological and chemical cont... More odorAn odor is a smell, often detectable by the human nose, whic... More persists more than 48 hours after cleanup, contaminationContamination is the presence of harmful or unwanted substan... More likely remains in a concealed location. This is a strong indicator that professional remediation is needed.

Health Risks of Sewage Exposure

SewageSewage is wastewater containing biological and chemical cont... More is classified as a biohazard because it contains active pathogensPathogens are microorganisms such as bacteria, viruses, or f... More capable of causing serious disease. Exposure during a sewage backup can occur through direct skin contact, ingestion of contaminated water or food, or inhalation of aerosolized particles.

Diseases associated with sewageSewage is wastewater containing biological and chemical cont... More exposure include:

• Hepatitis A (viral liver infectionInfection is the invasion and multiplication of harmful micr... More transmitted via the fecal-oral route)
• E. coli infectionInfection is the invasion and multiplication of harmful micr... More (can cause severe gastrointestinal illness and kidney failure)
• Salmonella (causes severe diarrhea, fever, and abdominal cramps)
• Leptospirosis (bacterial infectionInfection is the invasion and multiplication of harmful micr... More that can leadLead is a heavy metal that can be toxic to humans, especiall... More to kidney damage, meningitis, and liver failure)
• Cryptosporidiosis (parasitic infectionInfection is the invasion and multiplication of harmful micr... More causing severe diarrhea, particularly dangerous for immunocompromised individuals)
• Giardia (parasitic infectionInfection is the invasion and multiplication of harmful micr... More causing gastrointestinal illness)

Children, elderly individuals, pregnant women, and anyone who is immunocompromised face a significantly higher risk from sewageSewage is wastewater containing biological and chemical cont... More exposure. If any of these individuals were in the affected area, consult a healthcare provider even if no immediate symptoms are present.

When to Call a Professional Sewage Cleanup Company

Professional sewageSewage is wastewater containing biological and chemical cont... More cleanup is always the safer option. It is required in the following situations:

• The spill has spread beyond a single room. Multi-room contaminationContamination is the presence of harmful or unwanted substan... More requires industrial extraction equipment and full decontamination protocols that are not practical for DIY.
• The backup has been sitting for more than 24 hours. After 24 hours, bacterial and viral load increase significantly, making DIY cleanup substantially more hazardous.
• The backup originated from a main sewer line or septic system. These sources produce the highest contaminationContamination is the presence of harmful or unwanted substan... More levels and the largest volume of sewageSewage is wastewater containing biological and chemical cont... More.
• If there is any chance that sewageSewage is wastewater containing biological and chemical cont... More water contacted your HVAC system. Contaminated ductwork requires professional duct cleaning to restore safe indoor air qualityIndoor air quality (IAQ) refers to the condition of the air ... More.
• Structural materials (drywall, subfloorThe subfloor is the foundational layer beneath flooring mate... More, framing) are affected. Removing and replacing structural materials requires moisture mapping, controlled demolition, and clearance testing.
• Any household member has a compromised immune system, is elderly, or is pregnant. Elevated health risk justifies professional handling regardless of spill size.
• Visible moldMold is a type of fungus that grows in damp or humid conditi... More is present. MoldMold is a type of fungus that grows in damp or humid conditi... More that appears within 24 to 48 hours of a sewageSewage is wastewater containing biological and chemical cont... More backup indicates rapid colonization. Professional remediation is needed to contain it safely.

How Much Does Sewage Backup Cleanup Cost?

SewageSewage is wastewater containing biological and chemical cont... More backup cleanup costs vary based on the size of the affected area, the materials impacted, and whether structural restorationRestoration is the process of returning a property to its pr... More is needed. Use the table below as a general reference.

Scenario	Estimated Cost	Notes
Minor bathroom/utility area backup	$2,000 – $3,500	Contained spill, single room, no structural damage
Kitchen or laundry room backup	$2,500 – $4,500	May involve appliances and cabinetry
Basement sewageSewage is wastewater containing biological and chemical cont... More backup	$3,000 – $7,000	Larger area, potential flooring/drywall removal
Full home sewageSewage is wastewater containing biological and chemical cont... More backup	$7,000 – $10,000+	Structural materials affected, moldMold is a type of fungus that grows in damp or humid conditi... More risk
Septic tank pumping	$250 – $500	Add-on if a septic system is involved
Sewer line clearing (plumber)	$150 – $300	For a clogged municipal line

These figures reflect cleanup and water damage mitigation only. Structural repairs, flooring replacement, and contents restorationRestoration is the process of returning a property to its pr... More are billed separately. Most homeowners’ insurance policies cover sudden and accidental sewageSewage is wastewater containing biological and chemical cont... More backups, though coverage for gradual issues or sewer line damage varies by policy. Review your policy and contact your insurer as early as possible.

Contact RestorationMaster for Emergency Sewage Cleanup

RestorationMaster has responded to sewageSewage is wastewater containing biological and chemical cont... More backup emergencies throughout the United States. Our IICRC-certified technicians are available 24 hours a day, 7 days a week, and can be on-site within hours of your call.

We handle the complete cleanup and restorationRestoration is the process of returning a property to its pr... More process from start to finish: water extraction, disinfection, structural dryingDrying is the process of removing moisture from materials, s... More, demolition of unsalvageableUnsalvageable items or materials are too damaged, contaminat... More materials, moldMold is a type of fungus that grows in damp or humid conditi... More preventionPrevention refers to actions taken to reduce the likelihood ... More, odorAn odor is a smell, often detectable by the human nose, whic... More removal, and full property restorationRestoration is the process of returning a property to its pr... More. We also work directly with homeowners’ insurance companies and can document your claim from the initial assessment.

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Frequently Asked Questions

What is Category 3 water damage?

Category 3 is the IICRC S500 classification for grossly contaminated water that contains pathogenic agents and poses a significant health threat. SewageSewage is wastewater containing biological and chemical cont... More backup is always classified as Category 3. This classification requires full removal of all affected porousPorous describes a material that contains small openings or ... More materials and EPA-registered disinfection of all surfaces. It is the most serious water damage classification and cannot be treated the same way as a clean water leak.

How do you get rid of sewage smell after cleanup?

Persistent sewageSewage is wastewater containing biological and chemical cont... More odorAn odor is a smell, often detectable by the human nose, whic... More after cleanup means residual contaminationContamination is the presence of harmful or unwanted substan... More remains somewhere in the affected space, often in subfloorThe subfloor is the foundational layer beneath flooring mate... More cavities, wall voids, or drain traps. To eliminate it: use an EPA-registered odorAn odor is a smell, often detectable by the human nose, whic... More neutralizer (not an air freshener), run activated carbon air scrubbers, flush and treat all drains in the affected area, and inspect concealed spaces for hidden contaminationContamination is the presence of harmful or unwanted substan... More. If odorAn odor is a smell, often detectable by the human nose, whic... More persists after 48 hours, call a professional.

How do you prevent sewage backups?

The most effective preventionPrevention refers to actions taken to reduce the likelihood ... More steps are: have your sewer line inspected and cleaned every 1 to 2 years if you live in an older home or have trees near the sewer line, install a backwater valve on your main drain line, avoid flushing anything other than toilet paper, and have your septic tank pumped every 3 to 5 years if you are on a private system. If your neighborhood has experienced sewer backups during heavy rain, talk to your municipality about a backwater valve subsidy program.

Does sewage backup cause mold?

Yes. SewageSewage is wastewater containing biological and chemical cont... More backups create the two conditions moldMold is a type of fungus that grows in damp or humid conditi... More requires: organic material and moisture. MoldMold is a type of fungus that grows in damp or humid conditi... More can begin growing within 24 to 48 hours of a water intrusion event, and sewage-saturated materials like drywall, insulationInsulation is a material used in buildings to reduce the tra... More, and wood framing are highly susceptible. Thorough dryingDrying is the process of removing moisture from materials, s... More within the first 24 to 48 hours is the most important factor in preventing moldMold is a type of fungus that grows in damp or humid conditi... More growth after a sewageSewage is wastewater containing biological and chemical cont... More backup.