Sewage backup under a homeSewage Backup Clean-up Procedures & Standards
For sewage removal, sanitizing, contents salvage, carpet disposal

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Sewer backup or overflow cleanup procedures:

This article provides a list of septic or sewage backup cleaning procedures, recommendations and standards for buildings.

Citing expert sources we describe the key steps in evaluating, cleaning up & disinfecting a building where there has been a sewage spill. We include safety procedures as well as explanatory details. We include a list of sewage spill cleanup guidelines & standards articles in PDF format near the end of this article.

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.

Sewage Backup & Contamination Cleaning Procedures & Standards

Spraying a biocide at a mold remediation project (C) Daniel Friedman

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Advice for Rapid Disinfecting & Drying Out a Sewage Contaminated Building

In planning for the clean-up of a sewage contaminated building, there are important considerations that an onsite expert would consider, such as the safety of building entry, health risks to occupants in other building areas, the scope of clean-up work needed, what materials can be salvaged and what items should be discarded, and the protection of other building areas during cleanup, such as a consideration of the ease with which air or dust can move from a contaminated area into the occupied building space.

An appropriate response to sewage spills in a building goes beyond dumping some kitty litter on the ground.

Following other sewage backup cleaning steps given just below we include a source list of documents describing what experts advise at SEWAGE CLEANUP STANDARDS. This article is adapted from those documents.

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.

Steps in an Effective Approach to Cleaning up a Sewage Spill

  1. Immediate response to a sewage spill for safety of building occupants and for damage control are given

    at SEWAGE BACKUP, WHAT TO DO. If you have not read that article, do so, then return here. There we discuss building entry hazards such as electrical shock and other immediate risks.
  2. Inspect for scope of sewage backup & contamination: an inspection of the building interior and exterior is required to make sure that the scope of cleanup and disinfection will be adequate following any sewage or plumbing drain backup or leak.

    An inspection for mold or other contaminants in the same area, and further cleaning needs should be made at the same time so that you do not have to do the job twice. For upper building areas

    see MOLD CONTROL, FLOOD RESPONSE and for basements and crawl spaces also


    Watch out: in our experience [DF] when a building has been wet enough to allow water to enter even just the very bottom of a wall cavity, there is a high risk of harmful and costly mold contamination of both the interior wall cavity surfaces as well as wall insulation.

    Some materials (plaster, mineral wool or cellulose insulation) resist mold growth a bit more than others (drywall, fiberglass insulation, exposed wood surfaces).

    More advice on handling wall and floor cavities where the floors have been wet is at Step 6. FLOOD DAMAGED BUILDING CLEAN-UP for carpeting and rugs that have been wet by area or building flooding

  3. Decide who is going to perform the clean-up of the sewage spill: yourself or a professional contractor.
    • Reasons to hire a professional water restoration company:
      • Your insurance company is paying for the clean-up.
      • The total area of contamination and scope of work are just too large for you to handle
      • Sewage spill has been in place for 24-hours or longer
      • The building HVAC system (air conditioning, forced warm air heating system) has been contaminated
      • You or building occupants are people at extra risk: asthmatic, elderly, compromised immune system , infants
    • If you are going to perform the sewage spill cleanup yourself 
      • Wear rubber gloves, eye protection, rubber boots, impervious coveralls
      • Do not directly touch sewage material; sewage spill or sewage contaminated materials such as carpets, clothing, furniture that contact bare skin can cause a serious infection
      • Take extra care that eyes, open cuts or sores or similar high-risk areas do not come in contact with sewage; be sure to keep on eye protection when spraying or washing off items outdoors during salvage operations, as sprayed sewage droplets are unsafe.
      • Wash your hands frequently; wash and disinfect clothing, gloves, boots that are to be re-used. Effective hand washing requires plenty of soap and at least 30 seconds of active scrubbing.
      • Watch out: airborne water droplets of sewage contaminated water or cleaning water carry pathogens and are dangerous;

        Ensure that your vaccinations are up to date for tetanus and diphtheria. Vaccinations are also available for hepatitis A.

        Don't touch fecal waste nor raw sewage with bare hands

        Don't breathe or become wet by sewage waters

        Do not touch your eyes, nose, ears, nor open cuts or sores when working around sewage

        Do not eat, drink, apply lip balm or lipstick (!) and do not chew gum while working with sewage cleanup

        If you are accidentally wet by or touch sewage, stop and bathe.

        Clean everything: after working on sewage cleanup, change out of your work clothing and bathe; clean all clothing, equipment, tools that come into contact with sewage materials by using an appropriate sanitizer, or if appropriate, discard those materials.

  4. Remove salvageable & non-salvageable contents & furnishings from the affected area.

    Remove non-salvageable items for disposal: wet carpets and padding should have been removed and discarded as well as wet upholstered furniture & curtains. (Valuable area rugs may be able to be salvaged by professional cleaning and sanitizing). If walls are covered with plastic or vinyl wallpaper it should be removed as well to speed drying of drywall.

    Use plastic bags to collect discarded materials for removal from the property.

    If available, heavy-duty contractor-grade plastic bags will reduce the risk of tearing or or leaks. If you only have think kitchen garbage bags available, double-bag items for added safety.

    Remove, clean, & store salvageable contents: wet contents that can be cleaned (hard-surfaced furniture, dishes, plastic items) should be removed from the sewage backup area and if weather permits, placed outdoors in a sheltered area. If weather or security do not permit that step, place salvageable items on a plastic-covered area of a concrete garage floor or similar area where the risk of cross-contamination of other building areas is minimized and where floor cleaning after salvage will be easy.

    Where weather permits, complete cleaning of salvageable materials outdoors.

    Be sure that cleaned salvaged items are stored dry and protected from the weather but do not bring them back into the sewage spill area until cleaning in that area and dryout of that area as well as restoration work have been completed.

    For large sewage spill cleanup projects you may require a clearance inspection and testing before contents are returned to the area as well as before it can be occupied.

    Tip: clothing can usually be laundered or dry-cleaned; sheets, towels, blankets and similar bedding may also be salvageable by cleaning;

    Tip: take photographs of the sewage spill and of sewage or water-damaged building contents and materials to assist in a later inventory of losses. Photos can be particularly helpful if insured items must be disposed-of quickly as part of damage control for the building.

  5. Prevent cross-contamination: measures to assure that sewage contaminated soil was not tracked into the living area, or appropriate cleaning there if needed and that airborne sewage-contaminated dust (or mold spores) are not blown to other building spaces.
    1. Close doors between the contaminated area and other building rooms
    2. Use 6-mil plastic taped as necessary at open doorways that cannot be closed.
    3. Seal off HVAC air intake or outlet registers for systems that are (wisely) to be left shut down during the cleaning and drying procedure.
    4. Use negative air (fans blowing out through one or more windows) to keep air pressure in the contaminated area lower than in the rest of the building. This step helps prevent sewage-contaminated dust from being blown to other building areas.

  6. Demolition & removal of wastewater-contaminated materials: remove any suspect or contaminated drywall, carpeting, carpet padding, paneling, building insulation or similar materials in the affected area.

    Remove & dispose of drywall, baseboard trim, or wall paneling that have been wet by sewage.

    Evaluate the porosity of remaining building materials to decide on demolition/disposal vs. cleaning. Quoting from Morey (2007):

    Highly porous (permeance factor >10) materials that have been exposed to sewage backflow and have a value that exceeds the cost of restoration such as high-value rugs and carpet, upholstery, and other textiles should be removed and restored off site.

    Highly porous materials with low cost or replacement value, such as carpet cushion, carpet, cardboard, tackless strip, wicker, and straw, should be removed and discarded as soon as possible. Other materials, such as saturated mattresses and cloth upholstery, regardless of value, cannot be restored and should be discarded. If disposal is necessary, these materials should be bagged in plastic for removal to a proper disposal site.

    Semiporous (permeance factor of >1 to 10) materials, including items such as linoleum, vinyl wall covering and upholstery, and hardboard furniture, along with construction materials such as wood, painted drywall, and plaster, should be cleaned, disinfected, or replaced as part of the initial restoration process.

    If these materials are not removed or properly disinfected, they can become reservoirs for growth of microorganisms.

    Nonporous materials (permeance factor ≤1) such as Formica™, linoleum, vinyl, and tile finishing materials can be inspected for subsurface contamination with a nonpenetration moisture meter.

    Although these materials may be rated as nonporous, they must be evaluated carefully because contamination can migrate from the perimeter and become trapped below the surface. If migration of contamination below the surface has not occurred, these materials may be fully restored. -
    Morey (2007)

    Remove other sewage-contaminated contents: all porous material (cardboard, paper, books cloth) carpeting, carpet padding, upholstered furniture, mattresses, curtains, stuffed animals, wet books and similar items should be discarded. Discard food that has been contaminated or is in the contaminated area.

    Also discard items for which cleaning, even if technically possible, is not cost-effective - if it costs more to clean it than to replace it, it's trash.

    Use plastic bags to collect baggable demolition materials for removal from the property.

    Watch out: carpeting warning: while we frequently hear from readers whose building owner or cleaning company promise to "sanitize" wall to wall carpets that have been left in place, typically by using a carpet cleaning machine, steam, and spraying with a sanitizer. Those measures are unlikely to be effective.

    It is very difficult to adequately sanitize a thick dense material like carpeting and virtually impossible to adequately sanitize carpet padding and flooring below a sewage-spilled-on carpet.


    In more than 40 years of field inspection and lab testing I have not once found that steam cleaning of an in-situ carpet was able to penetrate to sufficient depth to sanitize dense carpets, carpet padding, floor surfaces below the padding, nor could it penetrate heavy upholstered furniture.

    Generally health department and departments of environmental protection or conservation recommend that such carpets and their padding be discarded.

    Valuable area rugs or carpets can sometimes be cleaned and sanitized by a carpet professional. In such cases the carpet is removed from the building for professional cleaning and disinfection off-site. Be sure to warn the professional that the area carpet was subject to a sewage spill.

    Watch out: don't try leaving a "to be salvaged" wet carpet rolled up and waiting for days: the level of contamination will increase as will mold growth, and as well bleeding colors may ruin the carpet. Prompt removal and prompt cleaning and drying will be required.

  7. Remove water & apply an initial disinfectant in the sewage spill area as quickly as possible: following removal of soaked contents.
    • Remove standing water using buckets, mops, sponges, water-removing shop vac (that will have to be disinfected or discarded after the project) or rented sewage spill cleanup equipment. Don't rent a shop vac for sewage spill cleanup without discussing that use with the rental service - doing so risks infecting someone else.
    • Collect and discard solid waste. Check with your local health department about requirements for bagging and disposal of solid sewage waste if it cannot be disposed-of into the public sewer system.
    • Initial disinfecting: After water removal, all affected materials should be decontaminated by spraying with a disinfectant solution. It is not the intent of this pre spray to effect full disinfection because the presence of organics precludes this. The objective is to initiate the reduction and containment of microorganisms as quickly as possible. - Morey (2007)
    • Prepare the affected area for rapid drying.

      At SEWAGE BACKUP, WHAT TO DO under damage control as well as earlier in this article we advised removing stored contents, both salvageable to be cleaned and not-economical-to-salvage to be discarded. Now the sewage-contaminated area should be empty of contents, giving room for further demolition and cleaning.

      Open lower wall cavities for the full length of walls along floors that were soaked with sewage effluent even if you do not see water stains on the upper walls themselves.

      Starting in the areas that were most wet, remove baseboard trim and cut away the lower 12" of drywall. If there are water stains above floor level, remove drywall to at least 12" above the high water mark. Remove wet wall insulation if present.

      Continue removing material around the room until you reach an area two feet past any area that was wet by sewage waters.

      Watch out
      : if a sewage backup soaked building floors in a finished space there is a good chance that wastewater has penetrated into the lower wall cavities.

      Removing baseboard trim and removing the lower 12-inches of drywall along the full length of walls that were soaked can reduce the chances of mold growth in the wall cavities, and exposure of those areas will also make building disinfection and the use of sanitizers easier later.

      Simply cutting a few holes or use of a "water extraction" procedure that relies on small holes in walls or on dehumidifiers alone will rarely be effective against mold contamination following building flooding if the wall cavity bottoms have been soaked.

  8. Wash the contaminated area surfaces that have been exposed after contents removal and drywall removal in the prior step.

    Use a household detergent solution to remove visible sewage contamination and dirt. (Some stains may remain in some materials and will be further disinfected in the next step).

    Watch out: failure to include this washing step means that disinfection / sanitizing, performed next, is likely to be ineffective.

    Additional cleaning: detergent washing & crack cleaning:

    Residual organic matter in cracks and crevices can be removed by pressure washing with a disinfectant solution.

    [pressure washing] solution then must be recovered with an extraction unit, immediately after application, to prevent further migration or saturation of contaminants into other porous materials. - Morey (2007)

  9. Dry the affected area as rapidly as possible: using a combination of portable fans and dehumidifiers. If we can dry a wet building area in 24-48 hours the chances of a costly mold contamination issue are greatly reduced.

    Dehumidifiers + Fans: When weather does not suggest opening building windows (rain, winter with heat on) one or more dehumidifiers combined with additional portable fans that stir building air will dry out a wet area far more quickly than the use of either a dehumidifier or a fan alone.

    Watch out: if the area has become mold contaminated fans stir airborne mold spores - an unsafe condition that requires use of a HEPA-filter respirator for working in the area and careful containment to avoid blowing contaminated dust into other building areas.

    Open windows + Fans
    : For dry clear weather an alternative dry-out procedure for wet building interiors can be followed using open windows.

    To avoid cross-contamination of other building areas it's best if the wet area is under negative air pressure with respect to the rest of the building.

    Fans blowing out from some windows can help speed air movement through the wet area.

    Watch out: fans, portable air conditioners & dehumidifiers used to move air containing sewage-contaminated droplets or airborne dust from the contaminated area will themselves become contaminated, unsanitary, and should not be re-used afterwards without cleaning or if that's not economical they should be replaced.

    Generally it won't make sense to both run a dehumidifier and have windows open - you would be trying to dehumidify the whole world.

  10. Second bacterial disinfection of the contaminated area. Professional cleaning companies use a variety of sanitizers and disinfectants beyond simple diluted bleach. The choice depends in part on just what surfaces and materials need treatment.

    Generally you should select a disinfectant described by its manufacturer as bactericidal - able to kill bacteria. As Morey (2007) points out, the disinfectant selected must be capable of inactivating potential pathogenic microorganisms on inert substrates.

    (DISINFECTANTS & SANITIZERS, SOURCES). The second disinfection treatment will be allowed to air-dry.

    Using bleach to disinfect a sewage spill area: If you are using bleach follow these guidelines & warnings
    • Bleach concentration: use a mixture of 3/4 of a cup household bleach per gallon of water (or other concentration recommended by the bleach or disinfectant manufacturer). Only use bleach that is labeled as Sanitizes or Kills Germs

      Technical detail: chlorine bleach solutions in concentrations sufficiently strong to act as disinfectants in a sewage-spill-contaminated building need to be at a concentration of 50 to 1000 ppm (parts per million) for disinfecting surfaces of appliances and food preparation areas.

      The chlorine concentration necessary for disinfecting walls and floors is 200 ppm.
    • Bleach disinfectant contact time: bleach or similar disinfectants must remain in complete surface contact for at least 15 minutes to be effective.

      Allow the disinfectant to air-dry on the treated surface. If the bleach solution dries in less than this amount of time an additional application should be made so that total contact time with the disinfectant is adequate. - Berry et als., U.S. EPA ret. 2/2014

      Watch out: Be careful using bleach: it is a powerful oxidant and should not contact skin or eyes; never mix bleach with ammonia - the result will be a release of dangerous chlorine gas. Watch out also that the use of bleach on most porous materials is likely to cause discoloration or loss of color.

      See MOLD CLEANUP, BLEACH for more advice.


      Watch out: do not rely on disinfectants, sanitizers, or sealants as a substitute for actual physical washing and cleaning. It is important to physically remove contaminated materials or mold from buildings. Use of sprays or sealants alone is not reliable and is never a substitute for actual cleaning.

      See MOLD CLEANUP - MISTAKES to AVOID where we discuss problems of unnecessary costs, cross contamination, using bleach to "kill" mold, reliance on ozone treatments and other snafus. If you or your contractor are thinking of using ozone generators in the building,


      Sanitizing a crawl space is described at CRAWL SPACE DRYOUT - home.

      Watch out: reliance on ozone generators is not a safe reliable way to disinfect a sewage contaminated building.

  11. Check for contaminated mechanical equipment: If building water supply, fixtures, appliances etc. were contaminated they will need to be cleaned and disinfected or if necessary replaced. Any possible effect on the building HVAC systems - for example a warm air heat or air conditioning duct system exposed to contamination.

    Inspect the interior of air handlers that are in or close to the sewage-backup area. Inspect for evidence of sewage waters entering HVAC ducts - for example if sewage water entered a ceiling where ductwork is also routed.

    Watch out: if HVAC equipment that moves air through the building was operated during the time of sewage contamination or sewage backup cleaning, that equipment and ductwork may be contaminated by unsanitary dust even if actual sewage liquid waste never entered therein.

  12. Check for cross-contamination of other building areas by sewage-contaminated water or debris tracked from the cleaning area to the reset of the building, or sewage-contaminated dust or water droplets that may have entered other building spaces or may have contaminated the air conditioning or heating systems.

    Simply noticing muddy of sewage-waste footprints passing out of the work area is evidence of floor contamination. Testing for contaminated dust or for high levels of sewage pathogens may mean a few surface tests for sewage contaminants in the living area, starting with the most-suspect areas of floors.

    If you need to take this step check with a certified environmental test lab licensed for your state or province to ask what swab or tape lift or other sampling methods the lab recommends.

  13. Check sewage or water ejecting systems & equipment: Examination of the sewage ejector pump to remove any other pending blockages and to assure that the proper type of sewage grinder pump, check valves, piping, etc. are installed.


  14. Choices of post-cleanup sealants: in areas prone to high moisture such as basements and crawl spaces, additional optional protection against mold growth can be obtained by using a sanitizer and when surfaces are dry, a sealant. See
  15. Prevent a future sewage backup:  to prevent a recurrence of building sewage spills see Step 4 found


  16. Sewage or flood warning systems: in low building floors, crawl spaces, basements, installation of a warning system that indicates if the sewage pump is not working, so that residents can stop using toilets and fixtures long enough to fix the problem and avoid future sewage spills in the structure.



  17. Building moisture control: in addition to removing contaminated soil (ok) in a flooded dirt floor basement or crawl area, typically we'd install a heavy plastic barrier to prevent soil moisture from continuing to enter the crawl area where it invites mold contamination.



    see CRAWL SPACE DRYOUT - home to be sure there are not other sources of water entry into the crawl area.

Sewage Backup & Contamination Cleaning Guidelines & Standards

The following articles giving excellent examples of sewage backup response procedures for buildings, including a discussion of the health concerns, cleaning procedures, special considerations for carpeting and other materials, and even disposal of sewage or wastewater backup cleaning wastewater. I have bold-faced the most helpful documents below.

Sewage or Septic Backup Cleanup Procedures & Standards Research


Continue reading at SEWAGE CONTAMINATION in BUILDINGS - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see SEWAGE CLEANUP PROCEDURES & STANDARDS FAQs - questions and answers posted originally on this page.

Or see CARPET MOLD / ODOR TESTS for carpeting or rugs that have been wet and may be mold-contaminated

Or see SALVAGE BUILDING CONTENTS - sorting & handling items that can or cannot be salvaged after flooding or sewage backup

Or see Step 4. BUILDING DRY-OUT PROCEDURES - emergency response to dry out a building after any sort of flooding

Or see Step 6. FLOOD DAMAGED BUILDING CLEAN-UP for carpeting and rugs that have been wet by area or building flooding

Or see this

Article series on sewage backups

Suggested citation for this web page

SEWAGE CLEANUP PROCEDURES & STANDARDS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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