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

Tarnagulla (Victoria) – E.coli

2007/8 Tarnagulla E.coli 1orgs/100ml 98.1% samples no e.coli (1 positive)

2012/13 Tarnagulla E.coli  3/100mL (96.4% samples no e.coli ) (2 positive)

2014/15 Tarnagulla 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

Tarnagulla (Victoria) – Trihalomethanes

17/3/16 Tarnagulla THM  0.26mg/L

18/4/16 Tarnagulla THM  0.27mg/L

6/6/16 Tarnagulla THM  0.31mg/L

12/3/20: Tarnagulla THM’s 0.31mg/L (max)

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

4/3/20: Laanecoorie THM 0.25mg/L. The concentration of Total Trihalomethanes (THMs) exceeded the health-based guideline value (i.e. 0.25 mg/L) specified in the ADWG in samples
collected in the Laanecoorie water supply system between March and April 2020. The raw water for the Laanecoorie WTP is sourced from the Loddon River. Historically, raw water from the
Loddon River is high in Natural Organic Matter (NOM) and bromide. The water age in the
Laanecoorie system is also high due to the size of storage tanks and lengthy water mains. The
high-water age, along with the high levels of NOM and bromide, leads to the formation of excessive disinfection by products (DPBs). To manage this issue, primary disinfection at the Laanecoorie WTP is achieved through chlorination, and then the treated water is chloraminated. Nitrification is a common problem for chloraminated water supply
systems, which causes difficulties in maintaining adequate disinfectant residual. Therefore,
the disinfection process at the Laanecoorie WTP was changed from chloramination to chlorination to manage nitrification issue in the distribution network for a short
period of time (i.e. between 17 February 2020 to 14 April 2020).

The elevated THM results were due to a combination of the following: the temporary switch to
chlorination; high concentrations of NOM and bromide in the raw water; and the high-water age in the system.The non-compliant results that were recorded are as follows: 04/03/2020
Customer tap Laanecoorie 0.27 mg/L 12/03/2020. Bealiba Tank Outlet 0.26 mg/L; Tarnagulla Tank Outlet 0.31 mg/L; and  Customer tap Tarnagulla. 0.30 mg/L 29/04/2020 Bealiba Tank outlet 0.28 mg/L; and Customer tap Bealiba 0.31 mg/LTrihalomethanes 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

Tarnagulla (Victoria) – NDMA

1/6/20 Tarnagulla NDMA 170ng/L

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

Tarnagulla – Victoria – Hardness (maximum)

2005/06: Tarnagulla (Victoria) – Hardness 400mg/L

2006/07: Tarnagulla (Victoria) – Hardness 490mg/L

2007/8 Tarnagulla Hardness 610mg/L

2008/9 Tarnagulla Hardness 490mg/L

2009/10 Tarnagulla Hardness 620mg/L

2010/11 Tarnagulla Hardness 220mg/L

2014/15 Tarnagulla Hardness 530mg/L

2015/16 Tarnagulla Hardness 230mg/L

2016/17: Tarnagulla (Victoria) – Calcium Carbonate 250mg/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.”

Australian Drinking Water Guidelines 2011

Tarnagulla – Victoria – Total Dissolved Solids (maximum levels)

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

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

2007/8 Tarnagulla Total Dissolved Solids 1400mg/L

2008/9 Tarnagulla Total Dissolved Solids 2400mg/L

2009/10 Tarnagulla Total Dissolved Solids 3100mg/L

2010/11 Tarnagulla Total Dissolved Solids 1600mg/L

2011/12 Tarnagulla Total Dissolved Solis 1300mg/L

2016/17: Tarnagulla (Victoria) – Total Dissolved Solids 1300 μS/cm


“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

Tarnagulla (Victoria) – Chloride

2007/8 Tarnagulla Chloride 600mg/L

2008/9 Tarnagulla Chloride 570mg/L

2009/10 Tarnagulla Chloride 570mg/L

2010/11 Tarnagulla Chloride 260mg/L

2016/17: Tarnagulla (Victoria)  Chloride 300mg/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

Tarnagulla –  Victoria – Iron

2007/8 Tarnagulla Iron 0.51mg/L

2008/9 Tarnagulla Iron 0.37mg/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

Tarnagulla (Victoria) – Sodium

2007/8 Tarnagulla Sodium 270mg/L

2008/9 Tarnagulla Sodium 240mg/L

2009/10 Tarnagulla Sodium 290mg/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

2019/20 – Tarnagulla – (Victoria) – Colour

2019/20: Tarnagulla (Victoria) Colour 16 HU (max), 3 HU (av.)

2019/20: Tarnagulla (Victoria) Customer Tap Colour 32 HU (max), 6 HU (av.)

Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.

“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…