2005/12 + 2019/20: Serpentine (Victoria) – E.coli, Trihalomethanes, Turbidity, Hardness, Total Dissolved Solids, Iron, Sodium, Chloride

Serpentine (Victoria) – E.coli
29/1/07: Serpentine (Victoria) 1org/100mL. (sample at customer tap)
No known cause – possibly due to low chlorine residual or bird entry. All possible entry points to the tank checked and sealed where necessary. Increased chlorine and ammonia dosage rates to gain higher CWS residual. Re-sampling completed showing no further E.Coli.

23/11/11 Serpentine E.coli  4/100mL


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

Serpentine (Victoria) – Trihalomethanes

Highest Level Only

2005/6 Serpentine Trihalomethanes 0.340mg/l

2007/8 Serpentine THM’s 0.290mg/L

2008/9 Serpentine Trihalomethanes 0.31mg/l

2010/11 Serpentine THM’s 0.36mg/L

Trihalomethanes Australian Guideline Level 250μg/L (0.25mg/L)

Why and how are THMs formed?
“When chlorine is added to water with organic material, such as algae, river weeds, and decaying leaves, THMs are formed. Residual chlorine molecules react with this harmless organic material to form a group of chlorinated chemical compounds, THMs. They are tasteless and odourless, but harmful and potentially toxic. The quantity of by-products formed is determined by several factors, such as the amount and type of organic material present in water, temperature, pH, chlorine dosage, contact time available for chlorine, and bromide concentration in the water. The organic matter in water mainly consists of a) humic substance, which is the organic portion of soil that remains after prolonged microbial decomposition formed by the decay of leaves, wood, and other vegetable matter; and b) fulvic acid, which is a water soluble substance of low molecular weight that is derived from humus”. Source: https://water.epa.gov/drink/contaminants/index.cfm

2005/6 – Serpentine (Victoria) – Turbidity

2005/6 – Serpentine (Victoria) – Turbidity 5.8NTU (maximum detection)

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

Serpentine (Victoria) – Hardness (maximum)

2005/06: Serpentine (Victoria) Hardness 430mg/L

2006/7: Serpentine (Victoria) Hardness 630mg/L

2007/8 Serpentine Hardness 620mg/L

2008/9 Serpentine Hardness 550mg/L

2009/10 Serpentine Hardness 370mg/L

2010/11 Serpentine Hardness 280mg/L

2011/12 Serpentine Hardness 230mg/L


“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.”

Serpentine – Victoria – Total Dissolved Solids (maximums)

2005/06: Serpentine (Victoria) – Total Dissolved Solids 2200 μS/cm

2006/07: Serpentine (Victoria) – Total Dissolved Solids 3300 μS/cm

2007/8 Serpentine Total Dissolved Solids 3400mg/L

2008/9 Serpentine Total Dissolved Solids 3500mg/L

2009/10 Serpentine Total Dissolved Solids 2800mg/L

2010/11 Serpentine Total Dissolved Solids 1900mg/L


“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.

Total dissolved solids (TDS) consist of inorganic salts and small amounts of organic matter that are dissolved in water. Clay particles, colloidal iron and manganese oxides and silica, fine enough to pass through a 0.45 micron filter membrane can also contribute to total dissolved solids.

Total dissolved solids comprise: sodium, potassium, calcium, magnesium, chloride, sulfate, bicarbonate, carbonate, silica, organic matter, fluoride, iron, manganese, nitrate, nitrite and phosphates…” Australian Drinking Water Guidelines 2011

Serpentine –  Victoria – Iron

2007/8 Serpentine Iron 0.52mg/L

2008/9 Serpentine Iron 0.46mg/L

2019/20: Serpentine Iron 0.48mg/L (max), 0.05mg/L (av)

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

Serpentine (Victoria) – Sodium

2007/8 Serpentine Sodium 500mg/L

2008/9 Serpentine Sodium 340mg/L

2009/10 Serpentine Sodium 300mg/L

2010/11 Serpentine Sodium 210mg/L

“Based on aesthetic considerations (taste), the concentration of sodium in drinking water
should not exceed 180 mg/L….The sodium ion is widespread in water due to the high solubility of sodium salts and the abundance of mineral deposits. Near coastal areas, windborne sea spray can make an important contribution either by fallout onto land surfaces where it can drain to drinking water sources, or from washout by rain. Apart from saline intrusion and natural contamination, water treatment chemicals, domestic water softeners and
sewage effluent can contribute to the sodium content of drinking water.” ADWG 2011

Serpentine (Victoria) – Chloride

2007/8 Serpentine Chloride 800mg/L

2008/9 Serpentine Chloride 690mg/L

2009/10 Serpentine Chloride 530mg/L

2010/11 Serpentine Chloride 440mg/L

2011/12 Serpentine Chloride 270mg/L

“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