2011 March – Avonsleigh (Victoria) – E.coli

Avonsleigh – (Victoria) – E.coli

On 11 March 2011, E. coli of 3 org/100mL was detected at a customer tap in Avonsleigh (Emerald sampling locality). The affected sampling tap was inspected and the water mains in the immediate area were fl ushed. Post samples collected from the affected sampling tap detected 31 orgs/mL of E. coli. Due to the high detection number, the whole distribution zone was fl ushed to clear the system. Chlorine levels were increased at each fl ushing location.
Further samples were taken at fi veother customer sampling taps within the locality and at the Gembrook Reservoir outlet. E. coli was not detected in the post samples collected at the 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