2013 February – Boronia (Victoria) – E.coli

Boronia – Victoria – E.coli
The fifth event was a detection of E. coli from a routine sample taken in Boronia on 4 February 2013. One organism per 100mL was detected and the free chlorine residual at the site of the detection was 0.16 mg/L. This sample tap falls within the Bayswater locality and is supplied by

Melbourne Water’s Boronia tank and associated secondary chlorinator. The area was flushed and all system checks were clear. Re-samples were taken the following day from the sample tap in question as well as nearby sample taps and all were free of E. coli.


Escherichia coli should not be detected in any 100 mL sample of drinking water. If detected
in drinking water, immediate action should be taken including investigation of potential
sources of faecal contamination.

“Coliforms are Gram-negative, non-spore-forming, rod-shaped bacteria that are capable of aerobic and facultative anaerobic growth in the presence of bile salts or other surface active agents with similar growth-inhibiting properties. They are found in large numbers in the faeces of humans and other warm-blooded animals, but many species also occur in the environment.

Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG 2011