Sewage contamination in building is the result of septic system backups or sewage pipe damages.  Sewage backflow in a building can damage the integrity of its structure and render it inhabitable as well. Sewage contains a range of pathogenic microorganisms like E.coli, Salmonella, Vibrio, mycobacteria, moulds, viruses and protozoa like Cryptosporidium and Giardia. Recurrent sewage leaks or spills in particular areas such as the basement of residential or commercial buildings, allow all these micro-organisms to proliferate. Exposure to these pathogens poses a serious health risk.

What Should One Do After Sewage Back-up?
Once a building gets contaminated with sewage, the most important steps to be taken are immediate removal of sewage water, disinfection of the contaminated surfaces, and prompt drying of the surfaces. Sewage remediation may require special equipment such as heavy duty vacuum cleaners. Hiring the services of remediation or restoration professionals is therefore recommended.

Documentation of contaminated materials is important. It’s difficult to clean contaminated porous materials. Therefore, any material that is porous (such as carpet, gypsum wallboard, insulation, upholstered furniture, clothing) and directly got contaminated by sewage is supposed to be discarded since the pathogenic micro-organisms have already penetrated the material.  Semi-porous material like wood furniture or pressed wood products may be thoroughly cleaned, disinfected and dried. Non-porous surfaces like metal, glass and ceramic tile floorings can be cleaned and disinfected.

Determining the effectiveness of sewage cleanup
Opinions differ as to whether microbial sampling to document effectiveness of sewage remediation is necessary. Those who think it’s not necessary argue that the primary objective of sewage remediation is to remove the sewage water and disinfecting and drying of contaminated interior surfaces. However those who support sampling recommend screening for E. coli and fecal coliforms.  E. coli (Escherichia coli in full) are found in the intestines of humans and animals and hence in fecal matter which happens to be a major component of sewage. Direct or indirect contact with E. coli contaminated water, food, air or surfaces could lead to harmful health effects. E. coli is only used as an indicator since not all strains of E. coli are pathogenic. However, E. coli strain O157:H7 is a toxin producing strain and potentially dangerous.

Even though sewage may contain many other pathogens, E. coli is the easiest to detect and identify. Hence the reason it’s used as a marker of sewage contamination.

To ensure that sewage decontamination has been effectively done, a swab test is performed on surfaces. A suspect area is identified and marked. A swab is uniformly rolled over the entire marked area (e.g. 10cm x10cm) and enclosed back into its container. Such swabs are sent to the lab at the earliest for analytical purposes. The lab would then process the swabs for detection of E. coli and other coliforms. Along with determining the presence or absence of E. coli, it is highly recommended to quantify them. Quantification gives us an idea of the bacterial load of the particular suspect area. This helps also determine the effectiveness of the disinfecting agent.

If the lab results are positive for E. coli and other coliforms, further cleaning would be required.