2005/11 – Wallan (Victoria) – E.coli, Iron

Wallan – (Victoria) – E.coli

On 24 November 2006, an E. coli test result of 2 organisms/100mL was reported at an entry point (water quality sampling point after chlorination) in the Wallan water sampling locality. Localised cleaning of water mains and spot chlorination of storages in the locality were undertaken. E. coli was not detected in the subsequent additional samples collected across
the locality.
On 11 November 2007, an E. coli test result of 1 organism/100mL was reported from a sample taken at the Pretty Sally Township Tank, supplying Wallan. The tank was immediately dosed with chlorine and the water mains in the area were cleaned. E. coli was not detected in
any of the subsequent samples from the tank or at customer taps.
On 31 January 2008, an E. coli test result of 1 organism/100mL was reported in a sample taken from a customer tap in the Wallan water sampling locality. Further water quality testing indicated the problem was localised to the Wallan distribution zone. In response the tank was isolated from the distribution system, drained, inspected, cleaned and repaired. The tank was refilled and dosed with chlorine. E. coli was not detected in the subsequent additional samples collected across the locality.
On 29 March 2010, E. coli of 1 org/100 mL was detected at a customer tap in the Wallan sampling locality. The area was block flushed and a visual inspection was performed. E. coli was not detected in the post samples collected at customer sampling taps. No subsequent action was required. (Yarra Valley Water Drinking Water Report 2009-10)
On 1 April 2011, E. coli of 2 orgs/100mL was detected at a customer tap in Wallan (Wallan sampling locality). Further samples were taken from other taps within the same locality and all
samples were clear of E. coli. The water mains in the immediate area were flushed and E. coli was not detected in the post samples collected at customer sampling taps. No subsequent action was required.
https://media.yvw.com.au/inline-files/Drinking%20Water%20Quality%20Report%202010-11.pdf

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

Wallan (Victoria) – Iron

2005/6: Wallan (Victoria) – Iron 0.42mg/L

Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.

Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011