2007 March – Dromana (Victoria) – E.coli

Dromana – (Victoria) – E.coli

The second E.coli detection in a routine sample was in Seacombe Avenue Dromana, in the Dromana locality, on 1 March 2007 (12 E.coli organisms per 100 mL). The sampling point is within the Safety Beach distribution area which is supplied from Dromana reservoir. Secondary disinfection also occurs at Dromana reservoir to maintain the good chlorine residual of 0.5 to 0.7 mg/L. The re-sample at the same customer tap and samples at three other nearby taps, taken 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