Sewer Backups

Testing For Bacterial Contamination and Cleaning Up Sewage Backups in Buildings
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.

Both a one-time event and recurrent sewage leaks into a building would be a concern, 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 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.
In fact a very high level of pathogens can present on the concrete, on the lower portions of furnishings, and on and inside of paneled wall cavity.
Demolition, cleaning, and disinfection may needed. These surfaces need to be then re-tested after cleaning and disinfection were complete.
Additional testing should be conducted to confirm that the workers did not contaminate other building areas during this cleanup.
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.
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.
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.