Why Test for Bacteria?

Damage from flood water containing sewage and feces is a very common problem encountered by home owners and building managers. Environmental professionals are often called to address the problems. Sewage wastewater, if it contains fecal waste, may be contaminated with a wide variety of microbes, including viruses, parasites, bacteria, and yeasts. Many of these are pathogenic to humans. These microbes must be properly removed with sewage wastewater and the environment/materials must be disinfected with appropriate biocides.

In the event of sewage water, flood water or other degraded water contamination, cleanup, disinfection and testing are necessary to ensure that the cleanup and disinfection are successful and the living environment is free of contamination from sewage associated microbes. Standard for contaminated water remediation have been set in ANSI/IICRC S500 Standard. Sometimes, only cleaning is not enough!

Sewage backup could lead to sewage contamination of the occupied spaces. Exposure to sewage contamination increases the risk of contracting diseases of the digestive system and other related illnesses.

Sources of sewage contamination may include raw sewage backup, severe flooding and leaking sewer lines or septic tanks. To determine the potential health risks from sewage contamination swab samples could be collected and tested for total coliforms, Escherichia coli (E. coli) and Enterococcus.

Sampling for indicator organisms can be performed before and after clean up. Sampling after cleanup is recommended to determine if the cleanup was successful.

Escherichia coli (E. coli)

As mentioned above the E. coli belong to the fecal coliform group. Presence of E. coli is a reliable indication of fecal or sewage contamination.


Enterococci are a subgroup within the fecal streptococcus group. Enterococci are typically more human-specific than the larger fecal streptococcus group. EPA recommends enterococci as the best indicator of health risk. They are rarer than the coliforms in the environment and are always present in the feces of warm-blooded animals.

Total Coliforms

Total coliforms are a group of related bacteria that are (with few exceptions) not harmful to humans. A variety of bacteria, parasites, and viruses, known as pathogens, can potentially cause health problems if humans ingest them. EPA considers total coliforms a useful indicator of other pathogens for drinking water.

On-Site Results

Rarefied Air Environmental has equipment that can act as a screening process for contaminants on surfaces or in water! The Hygiena® SystemSURE Plus® Luminometer is used in conjunction with Hygiena® Ultrasnaps (swabs) to detect the presence of Adenosine Triphosphate (ATP) which is found in organic matter and microorganisms. Certain levels can be used to measure the effectiveness of remediation activities. These levels also may be used to indicate whether certain water intrusion has even caused levels of concern with contaminants associated with black water losses.

Independent Laboratory Results

Confirmation swabs should also be collected and submitted to an independent and accredited laboratory. Samples are incubated for a period of 24 hrs. and will indicate the actual presence or absence of Total Coliforms, E. coli and Enterococcus.