2012 June – Werribee (Victoria) – E.coli

Werribee – Victoria – E.coli
one detection (one organism per 100mL) in a routine customer tap sample from Werribee locality on 21 June 2012. The cause for the detection is not known. No other samples, whether upstream or downstream, including repeat sampling, showed presence of E. coli .
one detection (two organisms per 100mL) in a non-routine sample in Werribee locality on 5 May 2014. The detection is considered to have been caused by the sample having been taken under non-aseptic conditions during commissioning of newly constructed water mains. Repeat sampling from nearby front garden taps confirmed the absence of E. coli in the water supply.

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