2008/10 – Gembrook (Victoria) – E.coli

Gembrook – (Victoria) – E.coli

On 21 January 2008, an E. coli test result of 4 organisms/100mL was also reported in a sample taken at the Gembrook High Level Tank which supplies the Gembrook Township. The tank was isolated from the distribution system, drained, inspected and cleaned. The tank was refilled and dosed with chlorine. E. coli was not detected in the subsequent additional samples collected across the locality.

On 18 January 2010, E. coli of 3 orgs/100 mL was detected at the Gembrook High Level Reservoir (Emerald sampling locality). This was due to rainwater seepage, following a heavy
rainfall event. A bypass supply was put in place whilst the tank was being repaired.
The roof of the tank was sealed and repaired to prevent rainwater seeping into the tank in the future. E. coli was not detected in the post samples collected at the reservoir and 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