Blackburn – (Victoria) – E.coli

On 29 November 2010, E. coli of 2 orgs/100mL was detected at a customer tap in Blackburn (Mitcham sampling locality). Another sample taken the same day at a customer tap in Vermont South (within the same Mitcham sampling locality) was clear of E. coli. The source supply to the locality and four other customer sampling taps in the locality were tested. The affected sampling tap was inspected and the water mains in the immediate area were flushed. E. coliwas not detected in the post samples collected at customer sampling taps.No subsequent action was required.

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