Cavendish (Victoria) – Trihalomethanes
2017/18: Cavendish (Vic) Trihalomethanes 362µg/L (max), 195µg/L (mean)
14/07/2017, 5/09/2017 & 23/11/2017 (3 single days). Cavendish Reticulation. THM results exceeded the ADWG health guideline values on three occasions
2018/19: (7/11/18 & 6/2/19) Cavendish (Vic) Trihalomethanes 291µg/L (max), 179µg/L (mean)
2019/20: (6/11/19 & 3/12/19) Cavendish (Vic) Trihalomethanes 304µg/L (max), 175µg/L (mean)
8/2/21: Cavendish Reticulation. 277µg/L(max), 170µg/L (av)
One (1) exceedance of the disinfection byproduct THM occurred at Cavendish during works undertaken to replace the liner of the clear water storage. With smaller temporary tanks in place, chlorine residual was increased to ensure adequate disinfection, which caused the exceedance. Once the works were completed, chlorine dosing returned back to normal operating conditions and THM levels reduced below health guideline values.
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/contaminant
Cavendish (Victoria) – Chloroacetic Acids
2011/12: Cavendish 0.120mg/L Dichloroacetic Acid (Highest Detection)
2010/11: Cavendish 0.140mg/L Dichloroacetic Acid (Highest Detection)
2009/10: Cavendish 0.130mg/L Dichloroacetic Acid (Highest Detection)
2009/10: Cavendish 0.140mg/L Trichloroacetic Acid (Highest Detection)
Australian Guideline Level: Dichloroacetic Acid 0.100mg/L, Trichloroacetic Acid 0.100mg/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
Cavendish (Victoria) – Chloral Hydrate
Cavendish 0.025ug/L Chloral Hydrate 2010/11
2004 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.02mg/L
2011 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.1mg/L
“Chloral hydrate is a disinfection by-product, arising from chlorination of water containing naturally occurring organic material (NOM). Chloral hydrate has only been detected by Goulburn Valley Water since changing to a new contract testing laboratory in November 2007. The Department of Health is currently conducting a study into the detection of chloral hydrate across Victoria.”
Cavendish (Victoria) – Aluminium
2008/09: Cavendish (Victoria) Aluminium 0.38mg/L (Highest Level Only)
2009/10: Cavendish (Victoria) Aluminium 0.42mg/L (Natural Sources)
2010/11: Cavendish (Victoria) Aluminium 2.5mg/L (Highest Level Only)
2011/12: Cavendish (Victoria) Aluminium 0.25mg/L (Highest Level Only)
2012/13: Cavendish (Victoria) Aluminium 0.28mg/L (Highest Level Only
According to the ADWG, no health guideline has been adopted for Aluminium, but that the issue is still open to review. Aluminium can come from natural geological sources or from the use of aluminium salts as coagulants in water treatment plants. According to the ADWG “A well-operated water filtration plant (even using aluminium as a flocculant) can achieve aluminium concentrations in the finished water of less than 0.1 mg/L.
The most common form of aluminium in water treatment plants is Aluminium Sulfate (Alum). Alum can be supplied as a bulk liquid or in granular form. It is used at water treatment plants as a coagulant to remove turbidity, microorganisms, organic matter and inorganic chemicals. If water is particularly dirty an Alum dose of as high as 500mg/L could occur. There is also concern that other metals may also exist in refined alum.
While the ADWG mentions that there is considerable evidence that Aluminium is neurotoxic and can pass the gut barrier to accumulate in the blood, leading to a condition called encephalopathy (dialysis dementia) and that Aluminium has been associated with Parkinsonism dementia and amyotrophic lateral sclerosis, the NHMRC, whilst also acknowledging studies which have linked Aluminium with Alzheimer disease, has not granted Aluminium a NOEL (No Observable Effect Level) due to insufficient and contradictory data. Without a NOEL, a health guideline cannot be established. The NHMRC has also stated that if new information comes to hand, a health guideline may be established in the future.
In communication with Aluminium expert Dr Chris Exley (Professor in Bioinorganic Chemistry
The Birchall Centre, Lennard-Jones Laboratories, Keele University, Staffordshire UK) in March 2013 regarding high levels of Aluminium detected in the South Western Victorian town of Hamilton
“It is my opinion that any value above 0.5 mg/L is totally unacceptable and a potential health risk. Where such values are maintained over days, weeks or even months, as indeed is indicated by the data you sent to me, these represent a significant health risk to all consumers. While consumers may not experience any short term health effects the result of longer term exposure to elevated levels of aluminium in potable waters may be a significant increase in the body burden of aluminium in these individuals. This artificially increased body burden will not return to ‘normal’ levels when the Al content of the potable water returns to normal but will act as a new platform level from which the Al body burden will continue to increase with age.
Cavendish (Victoria) – Colour
2011/12: Cavendish (Victoria) – Colour Apparent 27 HU (Highest Level Only)
2012/13: Cavendish (Victoria) – Colour Apparent 27 HU (Highest Level Only)
2013/14: Cavendish (Victoria) – Colour Apparent 74 HU (Highest Level Only)
2014/15: Cavendish (Victoria) – Colour Apparent 71 HU (Highest Level Only)
2015/16: Cavendish (Victoria) – Colour Apparent 78 HU (Highest Level Only)
2017/18: Cavendish (Victoria) – Colour Apparent 18 HU (Highest Level Only)
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…
Cavendish (Victoria) – Ammonia
2011/12: Cavendish (Victoria) – Ammonia 1.8mg/L (Highest level only – Ammonia as N)
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. (0.41mg/L mg of Ammonia as N)
“…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
Cavendish – Victoria – Turbidity
2013/14: Cavendish (Victoria) – Turbidity 13 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
Cavendish – Victoria – Iron
2015/16: Cavendish (Victoria) – Iron 0.36mg/L (Highest level only)
2018/19: Cavendish (Victoria) – Iron 0.401mg/L (Highest level only), 0.112mg/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