2016/19 – Werribee South (Victoria) – E.coli, Colour

Werribee South (Victoria) – E.coli

On 18 December 2018, City West Water reported to DHHS that there had been an E. coli detection (1 organism per 100mL) in a routine water sample from Werribee South ground level water supply tank (part of the supply to Werribee South water sampling locality) on 17 December 2018. On 18 December 2018, the following actions were undertaken including: isolating the Werribee South tank, confirming that there were no upstream water treatment plant or water quality supply issues and undertaking further water quality samples, in line with Schedule 2 of Regulations 2015.

In addition, on the 19 December 2018, a tank inspection was completed with no issues found, and the tank was dosed with chlorine.The outcome from these actions indicated no evidence, apart from the initial E. coli detection, to support that the water supply had been contaminated.In line with Schedule 2 of the Regulations 2015, it was concluded that the detection of E. coli was a “false positive”.


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

Werribee South  (Victoria) – Colour

2016/17: Werribee South (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…