2008/15: Lexton (Victoria) – E.coli, Trihalomethanes, Trichloroacetic Acid, Total Dissolved Solids, Colour, Hardness, Manganese

Lexton (Victoria): E.coli
27 November 2009: Lexton Customer Tap. E. coli – 25 orgs/100mL, E. coli – 66 orgs/100mL. Initial detections on non-routine samples. Resamples collected, chlorine residual raised at WTP and sections of main flushed. No E. coli detected in resamples. Informed DH of initial and resample results. Suspect initial samples taken were of private water supply.
(Central Highlands Water Annual Drinking Water Quality Report 2009-10)

“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

Lexton (Victoria) – Trihalomethanes

4 August 2008 – Lexton Customer Tap – Lexton Reticulation 0.67mg/L. More rigorous maintenance schedule developed. Informed DHS. (CHW Water Quality Report 2008/9)

2009/10: Lexton 0.790mg/L Trihalomethanes (Highest Level)

6 April 2010: Lexton Customer Tap. THMs – 0.790 mg/L Trichloroacetic acid – 0.230 mg/L Chloramination disinfection processes restored. Suspect elevated organics reacting with free chlorine prior to reversion to chloramination. Operational and system monitoring was intensified for the duration of the event.

13 May 2010: THMs – 0.450 mg/L

Trihalomethanes Australian Guideline Level 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

Lexton (Victoria) – Trichloroacetic Acid

2009/10: Lexton (Victoria) Trichloroacetic Acid 0.23mg/L

(Australian Drinking Water Guideline Trichloroacetic Acid: 0.1mg/L)

“Chloroacetic acids are produced in drinking water as by-products of the reaction between chlorine and naturally occurring humic and fulvic acids. Concentrations reported overseas range up to 0.16mg/L and are typically about half the chloroform concentration. The chloroacetic acids are used commercially as reagents or intermediates in the preparation of a wide variety of chemicals. Monochloroacetic acid can be used as a pre-emergent herbicide, dichloroacetic acid as an ingredient in some pharmaceutical products, and trichloroacetic acid as a herbicide, soil sterilant and antiseptic.” Australian Drinking Water Guidelines – National Health and Medical Research Council…

There are no epidemiological studies of TCA carcinogenicity in humans. Most of the human health data for chlorinated acetic acids concern components of complex mixtures of water disinfectant by-products. These complex mixtures of disinfectant by-products have been associated with increased potential for bladder, rectal, and colon cancer in humans [reviewed by Boorman et al. (1999); Mills et al. (1998)].” Ref: tmp/Trichloroacetic acid (TCA) CASRN 76-03-9 IRIS US EPA.htm

Lexton – Victoria – Total Dissolved Solids

2008/9: Lexton (Victoria) – Total Dissolved Solids 1430 mg/L

2009/10: Lexton (Victoria) – Total Dissolved Solids 1000 mg/L

2010/11: Lexton (Victoria) – Total Dissolved Solids 900 mg/L

2013/14 Lexton Total Dissolved Solids 950mg/L

2014/15 Lexton Total Dissolved Solids 900mg/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

Lexton  (Victoria) – Colour

2008/09: Lexton (Victoria) – Colour Apparent 35 HU

2009/10: Lexton (Victoria) – Colour Apparent 60 HU

2010/11: Lexton (Victoria) – Colour Apparent 120 HU

2011/12: Lexton Colour 40HU

2012/13: Lexton Colour 45HU

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…

Lexton – Victoria – Hardness

2008/09: Lexton (Victoria) – Hardness 480mg/L

2009/10: Lexton (Victoria) – Hardness 380mg/L

2010/11: Lexton (Victoria) – Hardness 370mg/L

2011/12: Lexton Hardness 270 mg/L

2012/13: Lexton Hardness 280 mg/L

2013/14: Lexton Hardness 420 mg/L

2014/15: Lexton Hardness 350 mg/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

Lexton – Victoria – Manganese

2008/09: Lexton (Victoria) – Manganese 0.5mg/L (highest level)

12 November 2009: Lexton Clear Water Storage Tank (Victoria) Manganese 0.7mg/L

Manganese: ADWG Guidelines 0.5mg/L. ADWG Aesthetic Guideline 0.1mg/L
Manganese is found in the natural environment. Manganese in drinking water above 0.1mg/L can give water an unpleasant taste and stain plumbling fixtures and laundry.