Estimated duration of incident: Isolated incident
Location of incident: Stanhope
Nature of incident: Detection of 2 org/100mL of E.coli in the standpipe at Stanhope. The cause is unknown but a sampling error is suspected. There was no E.coli detected in the reticulation.
Drinking water supplies potentially affected: Stanhope.
Action taken in response: Resampling of the Standpipe and reticulation in Stanhope. No further detections found.
Checked for evidence of ingress at the storages – none found. Treatment processes reviewed – no issues. No recent repairs carried out. Sampling equipment checked – no issues noted.
Communication with customers: Nil
DH notification: A Section 22 notification was sent to the Department of Health on 14/04/2014
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
Highest Detections only 2010/11
Stanhope 0.040mg/L Chloral Hydrate 2010/11
2004 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.02mg/L
2011 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.1mg/L
“Chloral hydrate is a disinfection by-product, arising from chlorination of water containing naturally occurring organic material (NOM). Chloral hydrate has only been detected by Goulburn Valley Water since changing to a new contract testing laboratory in November 2007. The Department of Health is currently conducting a study into the detection of chloral hydrate across Victoria.”