2007/2010 – Preston (Victoria) – E.coli

Preston – (Victoria) – E.coli

On 19 April 2007, E. coli test result of 3 organisms/100mL was reported from a sample collected from a hydrant at the corner of Gordon Grove and Murray Street, Preston during commissioning of a new water main. Testing is undertaken as a part of the process of commissioning of new mains and extensive cleaning of the water mains was carried out and subsequent samples collected from customer taps near the hydrant were clear of E. coli.

On 18 January 2010, E. coli of 1 org/100 mL was detected at a customer tap in the Preston sampling locality. The area was block flushed and the tap visually inspected. E. coli was not
detected in the post samples collected at customer sample 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