2010/11 – Wattle Glen (Victoria) – E.coli

Wattle Glen – (Victoria) – E.coli

On 15 June 2010, E. coli of 1 org/100 mL was detected at a customer tap in Wattle Glen (Mernda/ Hurstbridge sampling locality). The tap was exposed to soil from the surrounding garden bed, which is likely to have affected the reading. The chlorine level was checked at the
local reservoir and in the network and area was block flushed. E. coli was not detected in the post samples collected at customer sample taps. As a result of this incident, Yarra Valley Water works closely with the testing laboratory to ensure that set sampling protocols are strictly adhered to by all samplers. Yarra Valley Water will continue to audit laboratory processes, including sampling practices to ensure this event is not repeated in the future.
No subsequent action was required. (Yarra Valley Water Drinking Water Quality Report 2009-10)
On 18 March 2011, E. coli of 1 org/100mL was detected at a customer tap in Wattle Glen (Mernda/Hurstbridge sampling locality). Further samples were taken from other taps within the same locality and all samples were clear of E. coli. The water mains in the immediate area were
flushed and E. coli was not detected in the post samples collected at 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