2011 December + 2016/19 – Taylors Lakes (Victoria) – E.coli, Turbidity, Colour

Taylors Lakes – Victoria – E.coli
one detection (one organism per 100mL) in a non-routine customer tap sample from Taylors Lakes locality on 22 December 2011. The cause for the detection is not known. No other samples, whether upstream or downstream, including repeat sampling, showed presence of
E. coli.
On 3 January CWW detected E.coli of 1 organism per 100mL at Holden water supply tank (part of the supply to Taylors Lakes water sampling locality). On 4 January it was reported to DHHS and the following actions took place in line with Schedule 2 of the Safe Drinking Water Regulations 2015:-Holden tank was isolated, inspected and dosed withchlorine;- Melbourne Water’s upstream treatment processes andwater quality data was verified;-resampled at the tank and downstream at customers’ properties. The outcome from these actions indicated no evidence (apartfrom the initial E. coli detection) to support that the water supply had been contaminated. Therefore, in line with Schedule 2 of theSafe Drinking Water Regulations 2015
it was concluded that thedetection was a “false positive”.

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

Taylors Lakes – Victoria – Turbidity

2016/17: Taylors Lakes (Victoria) – Turbidity 5.7 NTU (Maximum detection during year)

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
consumer’s tap.

Taylors Lakes  (Victoria) – Colour

2018/19: Taylors Lakes (Victoria) – Colour Apparent 16 HU (Highest Level Only)

Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.

“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…