2016 October – Tranmere (Tasmania) – E.coli

Tranmere (Tasmania) – E.coli

E. coli exceedance occurred 10/10/2016 at CLSTE132 Tranmere/10 Norla St in the Clarence zone. A site investigation was conducted to determine the cause of the contamination and the surrounding pipelines were flushed, nearby reservoirs disinfected then a re-sample sent for analysis, which was clear. Investigation of the cause of the failure was inconclusive, however it was determined that the sample tap location was not representative of the network, therefore a new sample tap was installed in a more appropriate location.

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