Warburton – (Victoria) – E.coli
On 8 February 2007, an E. coli test result of 15 organisms/100mL was reported in a sample taken at the Four Mile Creek High Level Tank in Warburton. Water quality testing conducted extensively throughout the distribution zone immediately after detection indicated the problem was localised. The tank was isolated from the distribution system, drained, inspected and cleaned. The tank was refilled and spot dosed with chlorine. E. coli was not detected in the
On 22 March 2007, an E. coli test result of 2 organisms/100mL was reported from a sample taken at the Warburton High Level Tank supplying the Warburton locality. The tank was immediately spot dosed and the water mains in the area were cleaned. E. coli was not detected in any of the subsequent samples.
On 4 May 2007, an E. coli test result of 2 organisms/100mL was reported from a non-routine sample taken at a customer tap in East Warburton. All three storage reservoirs in the Warburton area were spot dosed and water mains in the East Warburton area were cleaned. A temporary chlorinator was installed to improve the chlorine residuals across the locality.
E. coli was not detected in any of the subsequent samples.
On 6 June 2008, an E. coli test result of 12 organisms/100mL was reported from a routine sample taken at a customer tap in Warburton. Further water quality testing indicated the problem was localised to the Ythan distribution zone. 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.
On 19 January 2010, E. coli of 7 orgs/100 mL was detected at a customer tap in the Warburton sampling locality. The contamination was possibly due to water entering the Four Mile Creek water tank following a heavy rainfall event. Testing at the tank on 20 January showed E. coli of
14 orgs/100 mL. The tank was immediately taken off-line, and the tank was flushed, cleaned and visually inspected before being re-filled and re-tested. The inspection found gaps in the roof and walls. These were repaired, and water mains in the area were also flushed. E. coli was not detected in the post samples collected at the tank and customer sampling taps. No subsequentaction was required. (Yarra Water Valley Drinking Water Quality Report 2009-10)
On 28 January 2010, E. coli of 1 org/100mL was detected at a customer tap in the Warburton sampling locality. This sample was collected as part of an investigation into the Ythan Tank in Warburton. The tank was subsequently spot dosed with chlorine. Gaps found in the roof and walls were repaired and the area was block flushed. E. coli was not detected in the post samples collected at customer sampling taps. No subsequent action was required. (Yarra Water Valley Drinking Water Quality Report 2009-10)
On 19 December 2011, E. coli of 2 orgs/100 mL was detected at the Warburton High Level Tank outlet (Warburton sampling locality). Two other customer sampling taps were tested downstream and all samples were clear of E. coli. Warburton High Level Tank was dosed with chlorine. E. coli was not detected in post samples collected from the reservoir or customer sampling taps. No subsequent action was required.
“On 10 November 2015, E.coli of 200 orgs/100ml was detected at Warburton high level tank within the Warburton sampling locality. A follow up sample prior to corrective actions also detected E.coli (120 orgs/100mL). The tank was immediately withdrawn from supply and the zone was supplied from an alternative source.
The affected distribution area was flushed and the tank drained, inspected, repaired, cleaned
and disinfected. Further investigation has suggested that the E.coli detection was most likely
caused by inadequate sealing of the tank roof.
Further samples at four other locations within the water sampling locality were clear of E.coli.
E.coli was not detected in the subsequent samples collected at the tank. Notification to customers was not required. The incident lasted for 31 hours. Tank repair works were
completed on 18 December 2015.”
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
Warburton (Victoria) – Turbidity
2007/08: Warburton (Victoria) – Turbidity 14 NTU (max)
2020/21: Warburton (Victoria) – Turbidity 5.1 NTU (max), 3.42 NTU (95th percentile)
Chlorine-resistant pathogen reduction: Where filtration alone is used as the water treatment
process to address identified risks from Cryptosporidium and Giardia, it is essential
that filtration is optimised and consequently the target for the turbidity of water leaving
individual filters should be less than 0.2 NTU, and should not exceed 0.5 NTU at any time
Disinfection: A turbidity of less than 1 NTU is desirable at the time of disinfection with
chlorine unless a higher value can be validated in a specific context.
Aesthetic: Based on aesthetic considerations, the turbidity should not exceed 5 NTU at the
2007/08 Warburton (Victoria) – Iron
2007/08: Warburton (Victoria) – Iron 0.34mg/L (max)
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