2015/18 – Gladstone (Tasmania) – E.coli, pH, Temperature


Gladstone (Tasmania) – E.coli

August 8 2015: Gladstone (Tasmania) – E.coli 2 MPN100/mL

November 10 2015: Gladstone (Tasmania) – E.coli 6.1 MPN100/mL

January 27 2016: Gladstone (Tasmania) – E.coli 1 MPN100/mL

February 9 2016: Gladstone (Tasmania) – E.coli 35.9 MPN100/mL

March 8 2016: Gladstone (Tasmania) – E.coli 4.1 MPN100/mL

April 19 2016: Gladstone (Tasmania) – E.coli 1 MPN100/mL

May 17 2016: Gladstone (Tasmania) – E.coli 2 MPN100/mL

June 15 2016: Gladstone (Tasmania) – E.coli 4.1 MPN100/mL

2016/17: Gladstone (Tasmania) E.coli 10 E.coli exceedences

11/7/2017 E.coli of 1 MPN/100mL in monthly compliance sample

8/8/2017 E.coli of 1 MPN/100mL in monthly compliance sample

12/12/2017 E.coli of 8.6 MPN/100mL in monthly compliance sample

14/02/2018 E.coli of 10.3 MPN/100mL in monthly compliance sample

13/03/2018 E.coli of 1 MPN/100mL in monthly compliance sample

2017/18: E.coli detections occurred during the period the system was subject to a BWA. A newly constructed WTP provides treated drinking water customers and the BWA was lifted 19 June 2018 and met the microbiological compliance target when Potable.

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

Gladstone (Tasmania) – pH (acidic)

Average pH: 2015 July-2016 June: 6.306 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
microbiological quality.

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. (ADWG 2011)

Gladstone – Tasmania – Temperature

December 15 2015: Gladstone (Tasmania) – Temperature 23.9C

January 27 2016: Gladstone (Tasmania) – Temperature 23C

February 9 2016: Gladstone (Tasmania) – Temperature 24.7C

March 8 2016: Gladstone (Tasmania) – Temperature 21.7C


“No guideline is set due to the impracticality of controlling water temperature.
Drinking water temperatures above 20°C may result in an increase in the number of

Temperature is primarily an aesthetic criterion for drinking water. Generally, cool water is more palatable than warm or cold water. In general, consumers will react to a change in water temperature. Complaints are most frequent when the temperature suddenly increases.

The turbidity and colour of filtered water may be indirectly affected by temperature, as low water temperatures tend to decrease the efficiency of water treatment processes by, for instance, affecting floc formation rates and sedimentation efficiency.

Chemical reaction rates increase with temperature, and this can lead to greater corrosion of pipes and fittings in closed systems. Scale formation in hard waters will also be greater at higher temperatures…

Water temperatures in major Australian reticulated supplies range from 10°C to 30°C. In some long, above-ground pipelines, water temperatures up to 45°C may be experienced…

The effectiveness of chlorine as a disinfectant is influenced by the temperature of the water being dosed. Generally higher temperatures result in more effective disinfection at a particular chlorine dose, but this may be counterbalanced by a more rapid loss of chlorine to the atmosphere (AWWA 1990).