2005/20 – Dunolly (Victoria) – E.coli, Trihalomethanes, NDMA, Hardness, Total Dissolved Solids, Chloride, Iron, Sodium, Ammonia

Dunolly (Victoria) – E.coli
24/1/07: Dunolly (Victoria) 1org/100mL. (sample at customer tap)
No known cause – possibly due to low chlorine residual or bird entry.  Laanecoorie WTP operating OK. All possible entry points to the Dunolly tank sealed. Sodium hypochlorite added to Dunolly tank (55 L). Resampling completed showing no further E.Coli.

2010/11 Dunolly E.coli  2/100mL (98.1% samples no e.coli ) (1 positive)

25/11/11 Dunolly E.coli  1/100mL

2012/13 Dunolly E.coli  1/100mL (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

Dunolly (Victoria) – Trihalomethanes

2005/06: Dunolly (Victoria) – Trihalomethanes 280μg/L (maximum during year)

17/3/16: Dunolly THM  0.28mg/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”. US EPA

Dunolly (Victoria) – NDMA

1/6/20 Dunolly NDMA 110ng/L (customer tap)

Since June 2020, the concentration of NNitrosodimethylamine (NDMA) has exceeded the health-based guideline value (i.e. 0.0001 mg/L) specified in the ADWG in samples collected from the Laanecoorie water supply system. NDMA is a disinfection by-product (DBP) of chloramination.
The non-compliant results that were recorded are as follows:
01/06/2020  Laanecoorie Water Treatment Plant Storage tank 0.00016 mg/L; Customer tap, Laanecoorie 0.00029 mg/L; and Customer tap Tarnagulla 0.00017 mg/L 24/06/2020 Customer tap Dunolly 0.00011mg/L

Given the health risks associated with DPBs, including NDMA, are based on life time exposure, occasional exceedances are considered low risk from a public health perspective. However, the
following corrective actions have been completed:
1. Checked and confirmed the chlorine: ammonia ratio that was being used to achieve chloramination was appropriate.
2. Increased the final water pH to ≥ 8.5. The samples tested for the presence of NDMA after the implementation of the corrective actions indicate that the actions were effective in reducing the
concentration of NDMA in the treated drinking water. Further investigations are currently
underway to better understand the root cause of the issue

“Based on health considerations, the concentration of NDMA in drinking water should not
exceed 0.0001 mg/L (100 ng/L). Action to reduce NDMA is encouraged, but must not compromise disinfection, as non disinfected water poses significantly greater risk than NDMA.

NDMA is used as an industrial solvent, an anti-oxidant, a rubber accelerator, and in the preparation of polymers, where it may be used as an initiator or a plasticiser. The compound has been used in the production of rocket fuel, as a biocide for nematodes, and an intermediate for 1,1-dimethylhydrazine to inhibit nitrification of soils.

NDMA is formed under mildly acidic conditions by the reaction of natural and synthetic secondary, tertiary or quaternary amines with nitrate and nitrite. Precursor amines include alkylamines, dimethylamine (DMA), tetramethylthiuram disulfide (thiram) and polyelectrolytes used in water and wastewater treatment. NDMA is also produced as a by-product of chloramination of drinking water (due to the presence of dimethylamine in source waters subject to wastewater discharges or the oxidation of natural organic matter by chlorine in the presence of ammonia) and to a lesser extent by chlorination. NDMA formation can be facilitated in soils by biochemical pathways in micro-organisms, and this compound is resistant to microbial degradation under both aerobic and anaerobic conditions. Ozonation of drinking water contaminated with the fungicide tolyfluamide can also lead to the formation of NDMA…

There are no data in the public domain or peer reviewed literature on NDMA in Australian drinking water distribution systems and water treatment plants. Anecdotal evidence suggests a bi-modal distribution, with several water authorities indicating that NDMA is present at levels at or near the limit of determination of 1 to 2 ng/L, whereas preliminary sampling and analysis by other authorities indicates levels in the range of 60-90 ng/L. A recent report from South Australia has indicated that NDMA may originate from rubber components of newly commissioned drinking water pipelines, regardless of the disinfectant used. This
may account at least partly for the divergent results reported by different water suppliers…” ADWG 2011

Dunolly – Victoria – Hardness (maximum detections)

2005/06: Dunolly (Victoria) – Calcium Carbonate 390mg/L (max)

2006/07: Dunolly (Victoria) – Calcium Carbonate 500mg/L (max)

2007/8 Dunolly Hardness 580mg/L

2008/9 Dunolly Hardness 490mg/L

2009/10 Dunolly Hardness 610mg/L

2010/11 Dunolly Hardness 240mg/L

2015/16 Dunolly Hardness 250mg/L

2016/17: Dunolly (Victoria) – Calcium Carbonate 240mg/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

Dunolly – Victoria – Total Dissolved Solids

2005/06: Dunolly (Victoria) – Total Dissolved Solids 1700 μS/cm (max)

2006/07: Dunolly (Victoria) – Total Dissolved Solids 2400 μS/cm (max)

2007/8 Dunolly Total Dissolved Solids 2800mg/L

2008/9 Dunolly Total Dissolved Solids 2400mg/L

2009/10 Dunolly Total Dissolved Solids 3100mg/L

2010/11 Dunolly Total Dissolved Solids 1600mg/L

2011/12 Dunolly Total Dissolved Solids 1400mg/L

2016/17: Dunolly (Victoria) – Total Dissolved Solids 1600 μS/cm (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.

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

Dunolly (Victoria) – Chloride (highest levels)

2007/8 Dunolly Chloride 590mg/L

2008/9 Dunolly Chloride 560mg/L

2009/10 Dunolly Chloride 580mg/L

2010/11 Dunolly Chloride 290mg/L

2016/17: Dunolly (Victoria)  Chloride 260mg/L

2019/20: Dunolly (Victoria)  Chloride 270mg/L (max), 220mg/L (av.)

“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

Dunolly –  Victoria – Iron

2007/8 Dunolly Iron 0.4mg/L

2008/9 Dunolly Iron 0.31mg/L

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

2007/10 – Dunolly – Sodium

2007/8 Dunolly Sodium 280mg/L

2008/9 Dunolly Sodium 250mg/L

2009/10 Dunolly Sodium 280mg/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
Dunolly  (Victoria) – Ammonia


2019/20: Dunolly Ammonia 0.511mg/L. 2019/20 average: 0.178mg/L

Based on aesthetic considerations (corrosion of copper pipes and fittings), the concentration
of ammonia (measured as ammonia) in drinking water should not exceed 0.5 mg/L.
No health-based guideline value is set for ammonia.

“…Most uncontaminated source waters have ammonia concentrations below 0.2 mg/L. High concentrations (greater than 10 mg/L) have been reported where water is contaminated with animal waste. Ammonia is unlikely to be detected in chlorinated supplies as it reacts quickly with free chlorine. Ammonia in water can result in the corrosion of copper pipes and fittings, causing copper stains on sanitary ware. It is also a food source for some microorganisms, and can support nuisance growths of bacteria and algae, often with a resultant increase in the nitrite concentration.” ADWG 2011