Mount Macdeon (Victoria) – E.coli
“McDonalds Tank, 20 February 2015 (Mt Macedon) Issue – Routine sampling at the tank resulted in detection of 2org/100mL of E.coli in the presence of 0.15mg/L free chlorine and 0.18mg/L total chlorine.
Actions – The tank was isolated from supply and spotdosed with chlorine to return a residual of 0.8mg/L free chlorine. The reticulation system was flushed to then draw freshly chlorinated water from the tank via pump station. Resampling was conducted for three consecutive days with all results clear of E.coli. Inspection of the tank was conducted and a point of potential ingress identified near the inspection hatch. The potential source of contamination was at the sampling point, due to overgrowth of weeds. Repair works were made to the inspection hatch and vegetation was cleared near the sample point. This tank will also be included in 2015/16 works to improve tank roof integrity following the trial of new technology.” Western Water Drinking Water Quality Report 2014/15
Escherichia coli should not be detected in any 100 mL sample of drinking water. If detected
in drinking water, immediate action should be taken including investigation of potential
sources of faecal contamination.
“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
31/1/17: Mount Macdeon (Victoria) – Trihalomethanes
Total Trihalomethane detection at McDonalds Tank, 31 January 2017 (Mount Macedon)
Issue – A prolonged dry period in 2015/16 reduced the water level in Rosslynne Reservoir to 15% capacity. Over several months from June-September, large rainfall events refilled the reservoir to 45% capacity. Changed activity within the catchment meant that the quality of water entering the reservoir changed in amount and type of organics. Under these conditions, Trihalomethanes were easily formed within the Rosslynne distribution system.
On 31 January 2016, the routine sample for McDonalds Tank detected Total Trihalomethanes of 0.26mg/L – above the ADWG limit (0.25mg/L). DHHS was notified on the day of the reported detection in accordance with the requirements of Section 18.
Actions – To prevent formation of Trihalomethanes, the treatment process at Rosslynne Water Filtration Plant was modified to reduce organics, and both the disinfection system at the plant and the Rosslynne network’s booster chlorination stations were also modified.
Outcome – External consultants conducted a review of the catchment, reservoir, plant and distribution network to assess the source of the organics and options to prevent future issues. Treatment options to prevent Trihalomethane formation during future refilling events included other types of chemical dosing and improvements to the disinfection system and storage tank management.
Mount Macedon (Victoria) Turbidity
2017/18: Mount Macedon (Victoria) Turbidity 13 NTU (max)
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
Mount Macedon (Victoria) – Aluminium
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.
Mount Macedon (Victoria) – pH (alkaline)
Average pH: 2012 July-2013 June: 9 pH units
Average pH: 2013 July-2014 June: 8.8 pH units
Based on the need to reduce corrosion and encrustation in pipes and fittings, the pH of
drinking water should be between 6.5 and 8.5.
New concrete tanks and cement-mortar lined pipes can significantly increase pH and
a value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in
pH is a measure of the hydrogen ion concentration of water. It is measured on a logarithmic scale from 0 to 14. A pH of 7 is neutral, greater than 7 is alkaline, and less than 7 is acidic.
One of the major objectives in controlling pH is to minimise corrosion and encrustation in pipes and fittings. Corrosion can be reduced by the formation of a protective layer of calcium carbonate on the inside of the pipe or fitting, and the formation of this layer is affected by pH, temperature, the availability of calcium (hardness) and carbon dioxide. If the water is too alkaline (above pH 8.5), the rapid deposition and build-up of calcium carbonate that can result may eventually block the pipe.
Mercury: Australian Drinking Water Guideline 0.001mg/L
Mercury, if it enters the ecosystem can transform into the more toxic methylmercury where it can bioaccumulate. Methylmercury is highly toxic to human embryos, fetuses, infants and children. Mercury has numerous sources including old gold mines, where mercury was used in gold recovery process. It has been estimated that 950 tonnes of
mercury was deposited into Victorian soil, rivers and streams during the various gold rushes.
Mount Macdeon (Victoria) – Cadmium.
2005/06: “Cadmium was detected in one water sample from Mount Macedon at a level exceeding the health-related guideline value set out in the Australian Drinking Water Guidelines (2004). This sample was taken in August 2005 and no other samples from this water supply system detected cadmium. The result was reanalysed by the laboratory, as possible cross contamination between sample bottles containing cadmium as a preservative for other samples may have occurred. No further elevated cadmium detections have occurred.” Victorian Drinking Water Quality Report 2005/06
ADWG Cadmium Guideline. 0.002mg/L. The primary route of exposure of cadmium is via contaminated water or food. Fertiliser can be a source of excessive cadmium as can rainwater tanks. It has been linked to cancer, lung disorders, kidney disease and autoimmune disease.