Colebrook (Tasmania) – E.coli (Temporary Boil Notice June 2016)
June 14 2016: Colebrook (Tasmania) – E.coli 15.8 MPN100/mL
June 21 2016: Colebrook (Tasmania) – E.coli 1 MPN100/mL
June 28 2016: Colebrook (Tasmania) – E.coli 2 MPN100/mL
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
Colebrook Disinfection Byproducts: Averages 2013-16:
2013/14: Trichloroacetic Acid: 199μg/L (Australian Guideline Level 100μg/L)
2015/16: Trichloroacetic Acid: 162μg/L (Australian Guideline Level 100μg/L)
2013/14: Dichloroacetic Acid: 133μg/L (Australian Guideline Level 100μg/L)
2015/16: Dichloroacetic Acid: 94.7μg/L (Australian Guideline Level 100μg/L)
*29/12/15: Monochloroacetic Acid 110ug/L (No Australian Guideline)
Highest Trichloroacetic Levels
“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
Colebrook Average Trihalomethanes 2013/14: 310μg/L (Australian Guideline Level 250μg/L)
Colebrook Average Trihalomethanes 2015/16: 278μg/L (Australian Guideline Level 250μg/L)
Colebrook 6/2/18: 1 Total Trihalomethane exceedance at COSTE81 of 251 ug/L. Reported to DoH Resampled Connected to the Greater Hobart system via a transfer pipeline (Regional towns program).
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
A Snapshot of Tasmanian Non-Microbiological Detections in Drinking Water July 2013-June 2014. Selected Breaches of Australian Drinking Water Guidelines (Friends of the Earth Australia)
Colebrook – Tasmania – Iron
August 11 2015: Colebrook (Tasmania) – Iron 399ug/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
Colebrook (Tasmania) – pH (alkaline)
Average pH: 2015 July-2016 June: 8.544 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.
When pH is below 6.5 or above 11, the water may corrode plumbing fittings and pipes. This, however, will depend on other factors such as the material used, the concentration and type of ions in solution, the availability of oxygen, and the water temperature. Under some conditions, particularly in the presence of strong oxidising agents such as chlorine, water with a pH between 6.5 and 7 can be quite corrosive.
Chlorine disinfection efficiency is impaired above pH 8.0, although the optimum pH for monochloramine disinfectant formation is between 8.0 and 8.4. In chloraminated supplies chlorine can react with ammonia to form odorous nitrogen trichloride below pH 7.
Chlorination of water supplies can decrease the pH, while it can be significantly raised by lime leached from new concrete tanks or from pipes lined with asbestos cement or cement mortar. Values of pH above 9.5 can cause a bitter taste in drinking water, and can irritate skin if the water is used for ablutions.
Colebrook – Tasmania – Turbidity
July 7 2015: Colebrook (Tasmania) – Turbidity 5.2 NTU
July 14 2015: Colebrook (Tasmania) – Turbidity 5.15 NTU
July 21 2015: Colebrook (Tasmania) – Turbidity 5.43 NTU
August 11 2015: Colebrook (Tasmania) – Turbidity 6.11 NTU
August 18 2015: Colebrook (Tasmania) – Turbidity 6.41 NTU
August 25 2015: Colebrook (Tasmania) – Turbidity 6.57 NTU
September 1 2015: Colebrook (Tasmania) – Turbidity 7.47 NTU
September 8 2015: Colebrook (Tasmania) – Turbidity 9.81 NTU
September 15 2015: Colebrook (Tasmania) – Turbidity 8.42 NTU
September 22 2015: Colebrook (Tasmania) – Turbidity 7.65 NTU
September 29 2015: Colebrook (Tasmania) – Turbidity 5.8 NTU
October 6 2015: Colebrook (Tasmania) – Turbidity 5.37 NTU
May 17 2016: Colebrook (Tasmania) – Turbidity 6.16 NTU
May 24 2016: Colebrook (Tasmania) – Turbidity 7.66 NTU
May 31 2016: Colebrook (Tasmania) – Turbidity 9.45 NTU
June 7 2016: Colebrook (Tasmania) – Turbidity 12.7 NTU
June 14 2016: Colebrook (Tasmania) – Turbidity 74.1 NTU
June 21 2016: Colebrook (Tasmania) – Turbidity 74.6 NTU
June 28 2016: Colebrook (Tasmania) – Turbidity 66.4 NTU
2016/17: Colebrook (Tasmania) – Turbidity 55.4 NTU (max), 3.44 NTU (mean)
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