2016/17 – Batesford (Victoria) – E.coli

April 13 2017 – Batesford (Victoria) – E.coli

Detection of Escherichia coli in drinking water (15 MPN/100ml). On 13 April Barwon Water was notified of a detection of E. coli and notified DHHS under section 22 of the Act in a water quality sample taken the previous morning from a reticulation entry point at Dog Rocks Tank, Dog Rocks Rd, Batesford. The relevant reticulation entry point (015E46) is located in the boosted zone of the Batesford water sampling locality.
An investigation was carried out in accordance with DHHS guidelines, along with corrective actions which included invoking incident response plans. Flushing of the Batesford system occurred along with disinfection of the tank for the pump boosted pressure zone. Alternate water supply for the boosted pressure system was implemented and the tank was taken offline.
After reviewing the investigation and action taken, DHHS confirmed this was a real event and the regulatory standard for E.coli had been breached during this event. As such, formal Section 18 notification to DHHS followed.

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