2009 September – Toorak – Cloverdale Ave (Victoria) – E.coli

Toorak – Cloverdale Ave – E.coli
The first four detections of E. coli all occurred on the same day, 29 September 2009, from routine samples where the location of the detections were supplied by three different localities. There were a number of other samples taken on the same sample run from these same localities that were clear of E. coli, which indicated that it had not spread throughout the localities. Due to the unexplainable detections, an incident was declared.
The second detection of E. coli occurred at Cloverdale Avenue, Toorak, (three E. coli organisms per 100 mL) with a free chlorine residual of 0.01 mg/L. The location of this sample point is located within the South Melbourne locality, which is supplied from Cardinia, Sugarloaf and Silvan Reservoirs.

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