2015 September – Garfield (Victoria) – E.coli, Colour

Garfield – Victoria – E.coli
The first notification was for a sample collected on 17 September 2015 from Garfield Basin with a recorded E. coli result of 1 org/100mL. The outlet sample tap is located approximately 15-20 metres from the sample point in the basin and therefore the sample tap needs to run for a number of minutes to get a representative sample. This is part of the sampling procedure at this site. The free chlorine measured on 17 September 2015 indicated that the tap had not been flushed sufficiently to get a representative sample. South East Water has reiterated with the laboratory that this procedure must be followed. Random auditing of samplers will also be undertaken in the future.
The Garfield Basin was isolated, with alternative supply to customers. The basin cover and water inside the basin was checked for any signs of security breaches, contamination or damage. There were no areas of concern.
The inlet supply was sampled and the basin outlet line was flushed and resampled on 18 September 2015. The samples taken on 18 September 2015 were clear of E.coli. A further resample was collected on 20 September 2015, which was also clear of E. coli.
Based on the results and investigation it was determined that the cause of the E.coli result was due to sample handling. After consultation with the Department of Health and Human Services, it was agreed this positive result was not representative of the drinking water supplied, and was
deemed to be a false positive as per the definition in the Safe Drinking Water Regulations 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

Garfield  (Victoria) – Colour

2015/16: Mordialloc (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…