2010 July – Thornbury (Victoria) – E.coli

Thornbury – (Victoria) – E.coli

On 26 July 2010, E. coli of 11 orgs/100mL was detected in Thornbury (Preston sampling locality). The sample was collected from a hydrant at the corner of Collins Street and Matisi Street
during the commissioning of a new water main. Testing is undertaken as part of the process of commissioning of new mains. Other samples taken from the new water main were clear of E. coli. The water mains in the immediate area were flushed. E. coli was not detected in
the post samples collected at customer sampling taps near the hydrant. 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