Photograph of sewer line break in a crawl spaceFirst Priority Actions for a Sewage Backup
4 Key Steps to Septic Backup or Sewer Backup Cleanup & Repair

  • POST a QUESTION or READ FAQs about how to stop an overflowing toilet, how to clean up a septic or sewage backup, how to fix backing up sewers and septic lines

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Sewage backup response:

What to do in response to a septic or sewer backup into or even outside and around a building or in response to building flooding: this article explains how to respond to septic system or sewer backups in a building.

Yes a toilet backing up is disgusting. It's also unsanitary and can be a serious health hazard in a building.

Here we explain the inspection, cleanup and other steps necessary to sanitize a building that has suffered flooding or sewage-contaminated backups as well as steps to return the building drain, waste, vent system to operation.

This article also explains how to stop a toilet from overflowing and it offers some first aid for toilet backups and other plumbing drain or sewer piping backup conditions.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

What to do When the Septic or Sewer System Backs Up At or In a Building

PHOTO of sewage contamination sludge on the floor in a basement from a sewer line backupIn this article series we explain the causes of & response to sewer or septic backups into buildings, the health hazards, testing, and cleanup of sewage backups, and the cure or prevention of future sewage or septic backup problems.

[Click any image for an enlarged, detailed version]

Just below in this article we give the first-response priorities & steps in a sewage spill or leak response.

Watch out: sewage spills contain contaminants that can cause serious illness or disease. Disease causing agents in raw sewage include bacteria, fungi, parasites, and viruses and can cause serious illnesses including Hepatitis A.

Step 1: Is the sewage-spill contaminated building safe to enter?

If a building has been flooded by sewage or wastewater there may be unsafe electrical wiring, bacterial and pathogen hazards, mold hazards, even unsafe mechanical systems.

Watch out: sewage spills contain contaminants that can cause serious illness or disease. Disease causing agents in raw sewage include bacteria, fungi, parasites, and viruses and can cause serious illnesses including bacterial infections, Tetanus, Hepatitis A, Leptospirosis, infections by Cryptosporidium & Giardia and gastrointestinal diseases.


You should assume that any surface or material touched by sewage is contaminated.

Watch out: Unless you are wearing appropriate safety gear, do not enter confined spaces that have been contaminated with sewage, as toxic, flammable or asphyxiating or even explosive gases including methane and hydrogen sulfide as well as airborne pathogens may be present.

Keep children & pets out of the sewage-spill area

At BUILDING ENTRY for DAMAGE ASSESSMENT we discuss safety procedures for people considering entering a building following a disaster including flooding or possibly sewage backups.

For sewage backups in tight spaces such as crawl areas, see CRAWL SPACE SAFETY ADVICE. Presuming that the building is safe to enter, go to step 2.

Step 2: damage control for sewage backups & spills

Toilet backupIf there are measures that can be taken to stop continued sewage entry or water spread through the building, such as stopping a TOILET OVERFLOW or even opening a door or window for fresh air or to reduce wastewater spread, do that.

If the sewage or wastewater are being spread by water from a burst plumbing supply or hot water heating pipe, turn off the water to the building and if needed for safety or to stop further you may also need to turn off the (hot water or steam) heating system.

Items that have been soaked and are not salvageable may best be placed outdoors. By removing wet and contaminated materials from the building it may be easier to inspect, repair leaks, and clean the building itself.

Watch out: do not handle sewage-contaminated materials without proper personal safety protection: there are bacterial, pathogenic, respiratory and infection hazards.

Watch out: generally we do not move already-contaminated building contents into a clean building area - doing so will simply expand the necessary scope and cost of building cleaning and disinfection. But where temporarily moving items outdoors is not practical, it may make sense to move wet or contaminated items that are to be salvaged into a concrete or tiled floor garage or similar area.

Items there can be later removed for cleaning and the clean-up of a hard-surfaced floor will be less troublesome than other surfaces.

If necessary get help from your local emergency authorities such as fire department and health department both for emergency response (such as pumping a flooded basement) or further building safety assessment.

See FLOOD DAMAGE REPAIR PRIORITIES. If the building water supply is by private well that was covered by floodwaters,


Step 3: sewage backup or spill cleanup

Step 4: prevent a sewage backup recurrence

Inaccessible and contaminated crawl area requires special protection and debris removal before a sewage spill can be addressed (C) Daniel FriedmanDisturbing as it may sound, we find that some buildings suffer chronic flooding, leaks, sewage backups and spills. It makes sense to do more than just clean-up a sewage spill: one needs to identify and repair the underlying problem that caused the sewage overflow, spill or backup.

Diagnose the cause of the sewage backup

The root cause of a sewage backup may be a simple single-event toilet overflow, a chronic drain clog


or private septic system failure problem


or even a natural disaster or area flooding.

If your building has had a septic or sewage system backup into the structure you will want to review this article

and DRAIN & SEWER PIPING - where we discuss sewer line leaks.

Separately, at SEWAGE BACKUP TEST & CLEANUP we discuss how to test for bacterial or other pathogens in a building - tests that may be useful after a sewage spill cleanup in order to assure that the building is acceptably clean.

If the event that caused the sewage or septic backup into the building has also left the building drain system clogged (likely if the entire system was flooded),

see BLOCKED DRAIN REPAIR METHODS to try clearing your blocked drain before going to more drastic measures. If you have had sewage back up and spill out of toilets into the building, cleanup is needed and you may face bacterial hazards.

The inspection for an underlying cause of chronic drain backups, toilet overflows, and sewage spills may need to include these less-direct causes:

Emergency Toilet Overflow Rescue Procedure - how to stop a toilet from overflowing

This topic has been moved to a separate article: please see TOILET OVERFLOW EMERGENCY

Question: what do we do about sewage found in our yard

Evidence of sewage backup outdoors near a drain line cleanout (C) PGWe did not know that the sewage was backing up out of pipe into the yard. (Pictures at bottom).

When we found out we used rubber gloves and heavy duty trash bags to pick up used toilet paper and waste as much as we could. We cannot afford to have a plumber or someone come out to cleanup.

How can we cleanup? What can we use or buy to cleanup? Where can we buy products? Just wondering, what could be the problem causing this backup?

Please advise as soon as possible both my husband and I are unemployed and do odd jobs when available. - Anonymous by private email 2017/04/19


Once you've cleaned up obvious sewage, paper, waste, there's not more that's likely to be appropriate nor needed outdoors; rain and time and soil bacteria should be sufficient PROVIDED that the source of the backup is repaired.

From your photo I see what looks like sewage backed up out of a white PVC drain line cleanout, but I'm not sure - it could also be an access to a septic tank or even a point in a septic drainfield.

If the pipe is connected to a public sewer than the drain line past that point has clogged and needs to be cleared - by hiring a plumber with a power auger or renting a drain cleaning tool. Keep in mind that if the clog is because the sewer pipe is broken then unclogging it won't suffice: the damaged section of piping will need to be dug up and repaired.

If the pipe is connected to a septic tank then the tank or drainfield is backing up or has failed.

If the septic system has failed or a sewer pipe is broken or clogged, the problem needs to be found and fixed. Otherwise the backup will continue and worse, it may back up into your home causing more costly and risky damage.

  1. Start at CLOGGED DRAIN DIAGNOSIS & REPAIR if drains in the building are slow or backing up
  2. If you think your house drains are not blocked,

  3. And then be sure to

    read SEPTIC FAILURE CRITERIA for help in determining if in fact the septic system has failed

Question: what to do about sewage flooded heating equipment or other mechanicals

2018/09/02 Richard Forget said:

Interesting document. I did not see any verbiage so my question is what protocols should be used for cleaning a furnace that was exposed to raw sewage?

When is a furnace beyond cleaning and would need to be replaced?

Your documentation also mentioned concerns about mould from prolonged exposure to raw sewage.

If the front of the drywall is not visibly showing mould contamination would it also be expected that the back side of the drywall to be the same?

Reply: suggestions for sewage backups affecting furnace heating equipment

First let's be sure we're on the same topic, as people don't use these words identically.

"Furnace" - means a forced air heating system.

"Boiler" - means forced hot water heat.

The distinction is important as you'll read below where we discuss moving contaminated air into other building areas.

Protocol for Cleaning a Heating Furnace Exposed to Sewage Flooding

In sum the same protocols will apply to a furnace exposed to a sewage backup as to one exposed to area flooding.

That is because the standard assumption is that floodwaters are unsanitary, and because any electrical or many other mechanical components actually inundated need to be replaced.

Even if the equipment runs after having been dried one cannot assume it is safe to operate, nor can one assume that it will not fail later because of ensuing corrosion.


And at the end of that article


on restoring flood damaged buildings
for more broad advice as well as our comments on heating system restoration guidance from FEMA and HUD - both of whom give incomplete and in my opinion somewhat risky guidance.

Additional warnings about health risks associated with sewage are in the REFERENCES section of this page.

Additional suggestions for sewage backups affecting furnace heating equipment

Distinguish among these exposures to sewage and sewage pathogens in the heating system and equipment:

Inundated or wet furnace or other equipment

1. Any mechanicals that were wet, such as an oil burner motor or electrical controls or a blower fan motor should be replaced

2. Refractory-fabric type combustion chamber liner that was wet should be replaced; refractory-brick liners may be salvageable.

3. The heating equipment, motors, controls, that were not inundated should be inspected for safe operating condition as they could still have been wet by splash-up

Furnace parts not inundated

4. Droplet aerosols & contaminated dust:

Because sewage cleanup by just about any means risks formation of aerosols or tiny droplets of sewage waters and also risks the movement of sewage-contaminated dust into area air even when the area has been dried, additional cleaning, disinfection and sanitizing are likely to be required for

It may be more economical to replace these parts than to disassemble, clean, and re-assemble them.

Watch out: if anyone ran the blower fan at all, even briefly, following flooding or a sewage backup, contaminated or pathogen-laden dust may have been blown through other areas of the HVAC duct system. In that case it’s likely that the remaining ductwork needs to be cleaned and sanitized.

Flexduct that was wet is not salvageable. Flexduct that was not wet but has been contaminated by airborne dust or droplets is not likely to be salvageable as it is not reliably cleaned and is likely to be further damaged by any mechanical cleaning effort.

Solid metal ductwork can usually be cleaned and sanitized if that work is performed thoroughly.

More details are at  FLOOD DAMAGE in DUCT WORK - flooded ducts need to be cleaned and sanitized and air filters replaced - found at

Watch out: following HVAC duct and air handler cleaning and disinfection or sanitizing, an expert should collect intelligently-chosen representative sampling locations to collect surface samples (usually sterile swabs) to be processed by a qualified laboratory to confirm that the surfaces are not still contaminated by sewage bacteria.

Watch out: the fact that you ask about cleaning for a specific appliance in an areas exposed to sewage backup suggests that incomplete or amateur sewage backup cleaning has been done at the site where the sewage backup occurred. Therefore one should not assume that health and sanitation of the heating system are the only topic that needs careful review.


Continue reading at SEWAGE CLEANUP STANDARDS - where we describe in more detail the steps in removing sewage & disinfecting & cleaning a building interior after a sewage backup or spill and where we provide documents with still more detail from experts on sewage spill remediation, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see SEWAGE BACKUP RESPONSE FAQs - questions & answers posted originally at this article






Or see these

Septic or Sewer Backup Articles

Suggested citation for this web page

SEWAGE BACKUP, WHAT TO DO at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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