2007/17 – Wadeye (Northern Territory) – E.coli, pH

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Wadeye (Northern Territory) – E.coli

2008/09: Wadeye E.coli 3 Number of detections. 18 – 20 December, 2008 Incident: In December 2008, Cyclone Billy crossed the coast close to the community of Wadeye. Heavy rain resulted in fl oodwater inundating large areas including a signifi cant portion of the Wadeye borefi eld. Scheduled microbiological monitoring detected varying levels of E. coli and very high levels of total coliforms throughout the water supply system.

2010/11: Wadeye E.coli 1 detection. 99% compliance during year

“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

Wadeye (Northern Territory) – pH (acidic)

2007/08: Wadeye pH 5.5

2008/09: Wadeye pH 5.7

2009/10: Wadeye 5.8 pH

2010/11: Wadeye 5.8 pH

2013/14: Wadeye 5.4 pH

2015/16: Wadeye 5.2 pH

2016/17: Wadeye 5.5 pH

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.