PHOTO of sewage contamination sludge on the floor in a basement from a sewer line backup Sewage or Septic Contamination in Buildings
Investigate, Test & Clean-Up Sewage Contamination

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Sewage backup cause, prevention, & response:

This article series explains how to deal with and test for sewage backup contamination, sewage contamination testing, inspection, and cleanup- remediation in residential and commercial buildings. If you have had sewage back up and spill out of toilets into the building, cleanup is needed and you may face bacterial hazards.

If you have had a sewage backup or burst house drain pipe in your building this document offers some advice on how to test for sewage contamination, bacterial and viral hazards, and links to sewage spill cleanup and bacterial hazard information regarding sewage and septic spill contamination.

We explain why and how testing for sewage contamination is performed and we discuss the urgency of proper cleanup following a sewage backup or spill in a building. The photo above shows what dirt and sewage sludge may look like in a basement after a sewer line backup.

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.

Testing For Bacterial Contamination and Cleaning Up Sewage Backups in Buildings

Sewage backup under a homeIf your building has had a septic or sewage system backup into the structure

In this article 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.

[Click to enlarge any image]

Checking buildings for indoor air quality or other contaminants which may affect occupant health should not omit inspecting and taking site history for evidence of sewage or septic system backups into the structure or basement or crawl space areas below the structure.

Gray water and black water (sewage) can cause a wide range of fungal, bacteriological, viral, and parasitic hazards in buildings.

The photo at left shows evidence of raw sewage overflow in the crawl space under a home. Although a new waste line was installed (the white pipe at the top of the photograph) no cleanup has been performed.

Both a one-time event and recurrent sewage leaks into a building would be aconcern, particularly if prompt and competent cleaning were not performed.

If recurrent sewage contamination has occurred more extensive building cleaning and treatment are likely to be required.

One reason that experts recommend very prompt treatment following a sewage backup in a building is the wish to avoid transmission of bacterial contamination to other building areas.

Examples of sewage bacteria and virus transmission might be by movement of people from contaminated areas to other building areas (tracking contaminated soil), and air movement of aerosolized particles or contaminated dust through the building by natural convection, heating and air conditioning equipment, or other sources of air and dust movement.

Wet crawl space unsafe to enter (C) Daniel Friedman

Testing for Sewage or Septic Contamination

PHOTO of sewage contamination effluent and water stains on the floor in a basement after a sewer line backup

Watch out: sewage spills contain contaminants that can cause serious illness or disease. The photograph above shows a rather innocent-looking wet concrete basement floor following a sewer line backup into this building. In fact a very high level of pathogens was present on the concrete, on the lower portions of furnishings, and on and inside the paneled wall cavity.

Demolition, cleaning, and disinfection were needed. These surfaces were then re-tested after cleaning and disinfection were complete.

Additional testing was conducted to confirm that the workers did not contaminate other building areas during this cleanup.

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.

For a detailed list of the pathogens found in common household wastewater such as a septic tank and drainfield, see also our discussion of pathogens in sewage
see what makes up the contents of residential sewage explained at SEWAGE PATHOGENS in SEPTIC SLUDGE.


While sewage may contain many pathogens harmful to building occupants, testing for this problem usually focuses on indicator organisms including total coliform, fecal coliform, Escherichia coli (E. coli), and Enterococcus as these species are expected in human sewage waste. They are potentially harmful themselves as well as serving as an indicator of sewage contamination.

How are Sewage Contamination Tests Conducted?

Copan sterile swab example, used for sewage contamination test at

Sterile Swab Tests for Sewage Contamination

Typical sampling methods to test for sewage contamination in buildings include use of sterile swabs on sample surfaces both in the suspected area and as a control in other building areas where low or no contamination is expected.

Step by step details of how sterile swabs are used to collect environmental samples of suspected mold, sewage, pesticide residue, or other substances are found at SWAB TEST KIT PROCEDURE

Swab tests for environmental sampling are also discussed at

Bulk Sample Tests for Sewage Contamination

Bulk samples of debris or building materials may also be collected, such as drywall suspected of having been wet with a sewage backup. Samples are sent to a qualified laboratory for culture and examination for these bacteria.

Since there are a variety of tests for bacteria and for possible sewage contamination, specification of the definitive lab test for sewage contamination is important where health concerns are at stake. Be sure to review the test choices with your laboratory before ordering a specific test as test accuracy and cost vary widely.

UV Light for Spotting Sewage Contamination& Urine

We also use UV light to screen buildings for sewage contaminants, urine, or other body fluids, including blood. See

Sewage Backup & Contamination Cleaning Guidelines & Standards


At SEWAGE & SEPTIC CONTAMINANTS we list the pathogens and contaminants commonly found in sewage and in sewage backup waters. In this article series we explain the causes of 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.


Continue reading at SALVAGE BUILDING CONTENTS if you need to remove and clean or salvage building contents such as clothing & furniture,or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see SEWAGE CONTAMINATION FAQs - questions and answers about sewage contamination in or around buildings.

Or see HEALTH DEPARTMENT HELP for RENTERS if your rental home has unsanitary or unsafe conditions that are not being addressed properly

Or see these

Sewage Contamination Articles

Suggested citation for this web page

SEWAGE CONTAMINATION in BUILDINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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