2011/23 – Penshurst (Victoria) – E.coli, Hardness, Chloride, Total Dissolved Solids, Turbidity, Iron

November 3/16 2011 – Penshurst (Victoria) – E.coli

3 November 2011: Penshurst. E.coli–50orgs/100mL. Inspected sample site and found illegal connection from private rainwater tank. Backflow prevention installed on rainwater tank. Reticulation flushed prior to receiving result. Resamples taken at site and upstream and

downstream of site. No E.coli detected in any samples. Informed DH of initial and resample results. Sample point has been moved to approximately 200m downstream of current site.
16 November 2011: Penshurst. E.coli–1org/100mL. Inspection of the sample site and resample. No E.coli detected in the re-sample. Informed DH of initial and resample results.

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

Penshurst – Victoria – Hardness

2011/12: Penshurst (Victoria) – Calcium Hardness 410mg/L (Highest Detection Only)

2012/13: Penshurst (Victoria) – Calcium Hardness 430mg/L (Highest Detection Only)

2013/14: Penshurst (Victoria) – Calcium Hardness 420mg/L (Highest Detection Only)

2014/15: Penshurst (Victoria) – Calcium Hardness 440mg/L (Highest Detection Only)

2015/16: Penshurst (Victoria) – Calcium Hardness 440mg/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

Penshurst (Victoria) – Chloride

2011/12: Penshurst (Victoria) – Chloride 300mg/L (Highest Detection)

“Chloride is present in natural waters from the dissolution of salt deposits, and contamination from effluent disposal. Sodium chloride is widely used in the production of industrial chemicals such as caustic soda, chlorine, and sodium chlorite and hypochlorite. Potassium chloride is used in the production of fertilisers.

The taste threshold of chloride in water is dependent on the associated cation but is in the range 200–300 mg/L. The chloride content of water can affect corrosion of pipes and fittings. It can also affect the solubility of metal ions.

In surface water, the concentration of chloride is usually less than 100 mg/L and frequently below 10 mg/L. Groundwater can have higher concentrations, particularly if there is salt water intrusion.

Based on aesthetic considerations, the chloride concentration in drinking water should not exceed 250 mg/L.

No health-based guideline value is proposed for chloride.” 2011 Australian Drinking Water Guidelines

Penshurst – Victoria – Total Dissolved Solids

2011/12: Penshurst (Victoria) – Total Dissolved Solids 830mg/L (Maximum Level)

2012/13: Penshurst (Victoria) – Total Dissolved Solids 780mg/L (Maximum Level)

2013/14: Penshurst (Victoria) – Total Dissolved Solids 810mg/L (Maximum Level)

2015/16: Penshurst (Victoria) – Total Dissolved Solids 790mg/L (Maximum Level)

2017/18: Penshurst (Victoria) – Total Dissolved Solids 780mg/L (Maximum Level)

2018/19: Penshurst (Victoria) – Total Dissolved Solids 810mg/L (Maximum Level)

2020/21: Penshurst (Victoria) – Total Dissolved Solids 817mg/L (Maximum Level)

2022/23: Penshurst (Victoria) – Total Dissolved Solids 1100mg/L (Maximum Level)


“No specific health guideline value is provided for total dissolved solids (TDS), as there are no
health effects directly attributable to TDS. However for good palatability total dissolved solids
in drinking water should not exceed 600 mg/L.

Penshurst – Victoria – Turbidity

2013/14: Penshurst (Victoria) – Turbidity 7.8 NTU (Maximum detection during year)

2014/15: Penshurst (Victoria) – Turbidity 6.2 NTU (Maximum detection during year)

2015/16: Penshurst (Victoria) – Turbidity 19 NTU (Maximum detection during year)

2018/19: Penshurst (Victoria) – Turbidity 30 NTU (Maximum detection during year)

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.

Penshurst – Victoria – Iron

2015/16: Penshurst (Victoria)  – Iron 2.9mg/L (Highest level only)

Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.

Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011