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Sewage Testing

Table of Contents

Normally sewage (bacteria) testing is performed after a known or suspected sewage spill or backup has occurred. This kind of testing should also be done after a sewage cleanup has been completed.

Every project is unique. We begin each project by listening to our client’s concerns and discussing possible options and strategize the most cost-effective way to determine the extent of the potential contamination or area needing clearance. 

Interpreting Results

E. coli

Escherichia coli (E. coli), is one of the main species of bacteria living in the lower intestines of mammals, known as gut flora. Discovered in 1885 by Theodor Escherich, a German pediatrician, and bacteriologist, E. coli are abundant: the number of individual E. coli bacteria in the feces that a human excretes in one-day averages between 100 billion and 10 trillion. However, the bacteria are not confined to this environment, and specimens have also been located, for example, on the edge of hot springs. The E. coli strain O157:H7 is one of the hundreds of strains of the bacterium that causes illness in humans.

As Gram-negative organisms, E. coli are unable to sporulate. Thus, treatments which kill all active bacteria, such as pasteurization or simple boiling, are effective for their eradication, without requiring the most rigorous sterilization which also deactivates spores.

Because of their adaptation to mammalian intestines, E. coli grows best in vivo or at the higher temperatures’ characteristic of such an environment, rather than the cooler temperatures found in soil and other environments.

Fecal Coliforms

Fecal Coliforms (sometimes fecal Coliforms) are facultatively anaerobic, rod-shaped, gram-negative, non-sporulating bacteria. They are capable of growth in the presence of bile salts or similar surface agents, oxidase negative, and produce acid and gas from lactose within 48 hours at 44 ± 0.5º C. The fecal coliform assay should only be used to assess the presence of fecal matter in situations where fecal Coliforms of non-fecal origin are not commonly encountered.

Fecal Coliforms include the genera that originate in feces; Escherichia as well as genera that are not of fecal origin; Enterobacter, Klebsiella, and Citrobacter. The assay is intended to be an indicator of fecal contamination or more specifically E. coli which is an indicator microorganism for other pathogens that may be present in feces.

Coliforms naturally occur in soil.

Normally this testing is performed after a known or suspected sewage spill or backup has occurred.

Confidentiality is always maintained with our client(s). American Air Testing does not release any information about any project with any other party than our client unless given written consent from our client or their agents.

All costs for our services are discussed and outlined clearly in our proposal before the project and again onsite before any sampling is collected.

How We Test

Bacteria swab or wipe samples are collected from known or suspected surfaces that have been impacted by a sewage spill or backup to determine the presence or absence of E. coli and Coliforms. This is normally done after professional cleanup has been completed. 

Bacteria (Sewage) Abatement Action

If laboratory results yield the presence of E. coli and/or Coliforms, professional cleaning within a specified radius from the sampling point is then recommended within what is referred to as a “bacteria abatement protocol”.

After bacteria abatement has been performed by a certified contractor, American Air Testing can provide post abatement validation testing. This testing’s purpose is to confirm that all contamination was cleaned up correctly.

Sewage Post Abatement Clearance Testing

If you run a school, public building, or commercial space that it is common sense to get a clearance document before someone complains they were contaminated by your sewage spill. Coliforms indicate the area was not properly cleaned and we will not issue clearance documents until both Coliforms and E.coli are absent.


CDC – Environmental Legionella Isolation Techniques Evaluation (ELITE) Program

The Centers for Disease Control and Prevention (CDC) offers a program that evaluates the proficiency of laboratories to detect Legionella bacteria, which can be found in sewage and water systems.

WHO – Guidelines for Safe Recreational Water Environments

The World Health Organization (WHO) offers comprehensive guidelines for safe recreational water environments, including testing for bacterial contamination.

NSF International – Wastewater Treatment Systems

NSF International provides certification and testing services for wastewater treatment systems, including bacterial clearance.

ASTM International – Standards for Water and Environmental Technology

ASTM International offers various standards related to water and environmental technology, including methods for bacterial testing.