2008/12 – Buninyong/Mt Helen (Victoria) – E.coli, Hardness, pH

Buninyong (Victoria): E.coli

18/11/08 (3 days): Buninyong Tank, Buninyong, (Ballarat System) 4 orgs/100mL. Tank dosed with chlorine and resampled. Resample results before tank dosed show E. coli – 5 orgs / 100 mL.
No E. coli detected in second set of resamples. Informed DHS of initial and
resample results. (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

3/12/10 (4 days): Buninyong Tank, Buninyong, (Ballarat System) 8 orgs/100mL. Site investigation and locality resamples collected. Confirmed disinfectant levels. Tank spot dosed with chlorine. No E. coli detected in resamples. Informed DH of initial and resample results.(Central Highlands Water Annual Drinking Water Quality Report 2009-10)

17 February 2012 (4 days ): Mt Helen Tank,Mt Helen (Ballarat System) E. coli – 27 org/100mL Buninyong/Mount Helen Reticulation (Ballarat System)

16 March 2012 (4 days) Buninyong Tank, Buninyong (Ballarat System) E. coli – 1 org/100mL Buninyong Reticulation (Ballarat System)

“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

Buninyong/Mt Helen (Victoria) – pH (alkaline)

Average pH: 2008 July-2009 June: 8.6 pH units

Based on the need to reduce corrosion and encrustation in pipes and fittings, the pH of
drinking water should be between 6.5 and 8.5.

New concrete tanks and cement-mortar lined pipes can significantly increase pH and
a value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in
microbiological quality.

pH is a measure of the hydrogen ion concentration of water. It is measured on a logarithmic scale from 0 to 14. A pH of 7 is neutral, greater than 7 is alkaline, and less than 7 is acidic.

One of the major objectives in controlling pH is to minimise corrosion and encrustation in pipes and fittings. Corrosion can be reduced by the formation of a protective layer of calcium carbonate on the inside of the pipe or fitting, and the formation of this layer is affected by pH, temperature, the availability of calcium (hardness) and carbon dioxide. If the water is too alkaline (above pH 8.5), the rapid deposition and build-up of calcium carbonate that can result may eventually block the pipe.

Buninyong/Mt Helen – Victoria – Hardness

2008/09: Buninyong/Mt Helen (Victoria) – Hardness 220mg/L (Highest Detection Only)


“To minimise undesirable build‑up of scale in hot water systems, total hardness (as calcium
carbonate) in drinking water should not exceed 200 mg/L.

Hard water requires more soap than soft water to obtain a lather. It can also cause scale to form on hot water pipes and fittings. Hardness is caused primarily by the presence of calcium and magnesium ions, although other cations such as strontium, iron, manganese and barium can also contribute.”

Australian Drinking Water Guidelines 2011