2013: Yarroweyah (Victoria) – E.coli

3/4/13: Yarroweyah. E.coli
E. coli – 24 MPN/100mL (98.1% samples during year within health guideline).

Date: 3/04/2013
Estimated duration of incident: Isolated incident
Location of incident: Yarroweyah & Strathmerton
Nature of incident: E.coli exceedances in the reticulation at Yarroweyah (24 MPN/100mL and 6 MPN/100mL). Coliforms also detected in Clear Water Storage, Water Tower and reticulation at Cobram, E.coli and coliforms in the Water Tower at Strathmerton and a single coliform in the reticulation at Strathmerton.
Drinking water supplies potentially affected: Cobram, Yarroweyah and Strathmerton
Action taken in response: Checked chlorine residuals at time of sampling, within limits. Investigation into incident revealed that there had been no water treatment process issues over the previous days, no CCP breaches had occurred. Storage checked for signs of ingress points, none found. Reticulation system flushed and response samples taken. All samples were clear of E. coli.
Communication with customers: nil
DH notification: A Section 22 notification was sent to the Department of Health on 5/04/2013.

4/12/13: Yarroweyah. E.coli
E. coli – 1 MPN/100mL (98.7% samples during year within health guideline).

Date: 4/12/2013
Estimated duration of incident: December 2013 to April 2014
Location of incident: Yarroweyah
Nature of incident: Three E.coli detections have been reported in the past twelve month period causing the rolling twelve month average to drop below the limit of 98% (97.1%).

Drinking water supplies potentially affected: Yarroweyah
Action taken in response: Nil
Communication with customers: Nil
DH notification: A Section 18 notification was sent to the Department of Health on 16/12/2013


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