2016-17 – Bartle Frere (Queensland) – Cryptosporidium, pH, Turbidity

Center map

Bartle Frere (Queensland) – Cryptosporidium

4/7/16: Bartle Frere Road, tap on property. Cryptosporidium. A detailed inspection of the Reservoir was conducted internally and externally. A diver was engaged to assess the reservoir condition and no cause was able to be identified within the reservoir. – Boil Water Advisory was in place 4/07/2016, cancelled 8/7/2016 – trend data and system analysis occurred – re-sampling was conducted until three satisfactory results were obtained, Qld Health and DEWS were consulted to ensure they were satisfied with results (07/07/2016)

Cairns Drinking Water Quality Management Plan 2016/17

“In recent years, Cryptosporidium has come to be regarded as one of the most important waterborne human pathogens in developed countries. Over 30 outbreaks associated with drinking water have beenreported in North America and Britain, with the largest infecting an estimated 403,000 people (Mackenzieet al. 1994). Recent research has led to improved methods for testing water for the presence of humaninfectious species, although such tests remain technically demanding and relatively expensive.

Cryptosporidium is an obligate parasite with a complex life cycle that involves intracellular development in the gut wall, with sexual and asexual reproduction. Thick-walled oocysts, shed in faeces are responsible for transmission. Concentrations of oocysts as high as 14,000 per litre in raw sewage and 5,800 per litre in surface water have been reported (Madore et al. 1987). Oocysts are robust and can survive for weeks to months in fresh water under cold conditions (King and Monis 2007).

There are a number of species of Cryptosporidium, with C. hominis and C. parvum identified as the main causes of disease (cryptosporidiosis) in humans. C. hominis appears to be confined to human hosts, while the C. parvum strains that infect humans also occur in cattle and sheep. C. parvum infection sare particularly common in young animals, and it has been reported that infected calves can excrete up to 10 billion oocysts in one day. Waterborne outbreaks of cryptosporidiosis have been attributed to inadequate or faulty treatment and contamination by human or livestock (particularly cattle) waste.

C. hominis and C. parvum can be distinguished from one another and from other Cryptosporidium species  by a number of genotyping methods. Infectivity tests using cell culture techniques have also been developed. Consumption of contaminated drinking water is only one of several mechanisms by which transmission (faecal-oral) can occur. Recreational waters, including swimming pools, are an important source of cryptosporidiosis and direct contact with a human carrier is also a common route of transmission.Transmission of Cryptosporidium can also occur by contact with infected farm animals, and occasionally through contaminated food.” ADWG 2011

2016/17 – Bartle Frere (Queensland) – pH (alkaline)

2016/17 – Bartle Frere (Queensland) – pH 8.6 (av. 2016/17)

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.

2016/17 – Bartle Frere – Turbidity

2016/17: Bartle Frere – Turbidity 5.1NTU (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
consumer’s tap