2009/12 – Forest Hill (Victoria) – E.coli, Turbidity

Forest Hill (Victoria): E.coli
28 February 2011: Forest Hill Customer Tap E. coli – 1 org/100mL. Site investigation and locality resamples collected. Confirmed disinfectant levels and correct operation of plant. Maintenance records checked to confirm no mains bursts in reticulation system. No E. coli detected in resamples. Informed DH of initial and resample results. (Central Highlands Water Annual Drinking Water Quality Report 2010/11)

25 June 2012 (3 days) Smeaton Tanks (Forest Hill System) E. coli – 1 org/100mL Forest Hill Reticulation

“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

Forest Hill – Victoria – Turbidity

2009/10: Forest Hill (Victoria) – Turbidity 6.5 NTU (Maximum detection during year)

2010/11: Forest Hill (Victoria) – Turbidity 8.6NTU (max), 0.8NTU (average)

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.