2009 April – Somerville – Webbs Lane (Victoria) – E.coli

Somerville – Victoria – E.coli
The final E.coli detection was from a routine sample taken at Webbs Lane, Somerville, in the Somerville locality, on 27 April 2009 (two E.coli organisms per 100mL) with a free chlorine residual of 0.01 mg/L. The sampling point is within the Webbs Lane Booster Distribution Zone
supplied by Cardinia Reservoir via Somerville Tank. All system checks were clear, the tank was dosed to 0.5mg/L and the re-sample at the same tap, one other sample point within the distribution zone, and also from the Somerville Tank, taken on the following day were
clear of E.coli.

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