2006/10 + 2012/13 – Rochester (Victoria) – E.coli, Sulphate, Turbidity

Rochester (Victoria) – E.coli
9/3/07: Rochester (Victoria) 4org/100mL. (sample at tank outlet)
No known cause. All possible bird entry points checked. Chlorine residuals checked and seem OK. Re-sampling completed showing no further E.Coli

2012/13 Rochester E.coli  66/100mL (98.1% samples no e.coli ) (1 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

2006/07 – Rochester (Victoria) – Sulphate

2006/7: Rochester (Victoria)  Sulphate 910mg/L

“Based on aesthetic considerations (taste), the concentration of sulfate in drinking water
should not exceed 250 mg/L. Purgative effects may occur if the concentration exceeds 500 mg/L.

Sulfate occurs naturally in a number of minerals, and is used commercially in the manufacture of numerous products including chemicals, dyes, glass, paper, soaps, textiles, fungicides and insecticides. Sulfate, including sulfuric acid, is also used in mining, pulping, and the metal and plating industries. Barium sulfate is used as a lubricant in drilling rigs for groundwater supply.
In the water industry, aluminium sulfate (alum) is used as a flocculant in water treatment, and copper sulfate is used for the control of blue-green algae (cyanobacteria) in water storages.
The highest concentrations reported in drinking water overseas are from groundwater supplies where the presence of sulfate is due to natural leaching from rocks. Concentrations have been reported up to 2200 mg/L. In source waters, concentrations are typically less than 100 mg/L.
The taste threshold for sulfate is in the range 250–500 mg/L.” ADWG 2011

2007/10 – Rochester (Victoria) – Turbidity

2007/8 Rochester Turbidity 13 NTU

2009/10 Rochester Turbidity 16 NTU

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