Palerang
Indicator: Drinking Water Quality
Results for this indicator are also available for [an error occurred while processing this directive]
What the results tell us for Palerang
The two small public water supplies of the Council area, Bungendore and Captains Flat, show a consistently high quality of drinking water. The Braidwood supply has shown E. coli present in the drinking water at intervals over the last eight years. This indicates a potential concern for health due to problems with the disinfection of the supply, which should be rectified.
Quality of the water supplied
Data are available for the Braidwood supply drawn from the Shoalhaven River, Bungendore Bore and Captains Flat Dam supply systems. These systems collectively supply water to about 3,500 people living in Palerang Council.
Thirty six water quality parameters were measured, including Total Coliforms and E.coli. No comment has been made on Total Coliforms, as this parameter does not reflect health risk. Herbicides and pesticides were not measured. Where the NH&MRC Guideline Values for Drinking Water have been exceeded, this is commented upon in the report for each supply source.
Braidwood water supply
This system draws water from the Shoalhaven River and supplies approximately 1,100 people in the Braidwood township and immediate area. The supply is chlorinated but receives no other treatment. The microbiological indicators were measured in 200 samples and the majority of inorganic constituents in 6 or more samples. Free chlorine, which is a measure of the disinfecting capability of the supply, was measured in 186 samples, pH in 168 samples, nitrate, nitrite, manganese, lead, fluoride, copper, chloride and total dissolved solids were measured 6 times.
Fourteen instances of E.coli present in the supply were reported over the 4 years, with the highest count being 83 organisms per100mL of water on 21st March 2007. Three more occurrences were recorded in October/November 2007, with a maximum of 10 organisms per 100mL of water. In 2005 there were 3 occurrences, with a maximum of 5 organisms per 100mL, and in 2007 one instance of 1 organism per 100mL. In 2008 there were three samples on one day (14th January) which contained 32, 22 and 11 organisms per 100mL water, and samples on 2nd January 2008 and 15th March 2008 which recorded one organism per 100mL in each.
This record follows a similar report for 2000-2004, in which a total of 17 samples across all years showed E.coli present in the drinking water. Between 5 and 16 organisms per 100mL of water occurred in samples in each of the 4 years.
This shows a low quality of disinfection control of the supply over the 8 years for which data is available, and requires rectification.
The pH was measured 168 times, and exceeded the NH&MRC recommended range on 112 occasions. The mean pH was however 8.5 and the maximum 9.5, which are close to the recommended range of 6.5-8.5. These pH results are not of health concern. Free chlorine was measured 186 times and 4 samples exceeded the Guideline Value of 5.0mg/L, with the highest 8.8mg/L, however this is not a major health concern. No other inorganic components were of concern.
Bungendore supply
This system draws from the Bungendore Bore supply and provides drinking water for approximately 2,000 people, in an expanding community. The water supply comes from the Bore and is aerated and chlorinated.
One hundred and ninety samples were assessed for E.coli, and one sample in November 2006 showed 10 organisms per 100mL. No other samples showed presence of these organisms. Of the 35 parameters measured in the water samples, all were within the NH&MRC Guideline Values, apart from a single slightly high aluminium concentration. An excellent quality water supply.
Captains Flat supply
This system draws water from Captains Flat Dam and supplies approximately 450 people in Captains Flat. The supply is chlorinated for disinfection. One hundred and two samples were assessed for E.coli, and one sample showed one organism per 100mL water.
The pH was measured in 27 samples and 4 exceeded the recommended range of 6.5-8.5. The mean pH was 7.7, within the recommended range, and the highest value was 9.1. These values do not provide a health concern. Thirty two samples were assessed for free chlorine and 5 exceeded the Guideline Value of 5.0mg/L. The mean value for chlorine was 1.9mg/L, well below the Guideline, and the maximum 7.6mg/L. These values are not of health concern. A consistently good water supply.
About the data
Drinking water quality is monitored as part of the NSW drinking water monitoring programme for publicly-provided water supply services, and detailed results can be accessed through the website http://www3.health.nsw.gov.au/waterqual/samples/register.cfm.
This report on drinking water quality for 2004-2008 is prepared from examination of this data, to illustrate the quality aspects of the water supplied for domestic consumption in the Council area.
Most residents in Palerang live outside the reticulated public water supply services provided in the three main villages, however no data is available on the quality of their private water supplies.
Interpreting the data
In 2004 the National Health and Medical Research Council introduced the Australian Drinking Water Guidelines, which provide the basis for quality assessment. These Guidelines have not included Total Coliforms as a measure of water quality for health purposes, as the organisms are widely present in soil and untreated water and grow in water pipes, and do not reflect the content of pathogenic organisms. Monitoring for Escherichia coli is, by contrast, particularly informative, since this organism occurs in large numbers in faeces and hence is an effective indicator of faecal contamination. It is killed by standard drinking water treatment and therefore should not occur in domestic supplies. The drinking water Guideline Value is zero organisms per 100ml sample and any detected organisms present in the water therefore exceed the guideline, and should result in an increase in the disinfection of the supply.
This remedial action should be taken until the E. coli count returns to zero.
While there are many other pathogens present in faecal contamination of water, monitoring of E. coli has been shown to be an effective and straightforward method for public health. Where the data from a water supply for this period show E .coli present, it has been commented upon for each water supply reported.
Concentrations of inorganic components of water supplies do not have such a sharp impact on health as faecal contamination. The Guideline Values reflect safe concentrations for lifetime exposure, and minor exceedences, which briefly occur, are of negligible risk to public health. Inorganic constituents become a risk to public health when they consistently exceed the Guideline Values, with the risk increasing with the concentration in the supply. Where these have occurred, they are commented upon in the appropriate section of the report. Unless there is accidental contamination of the supply, it is unlikely that any substantial variations in concentration of inorganic components will occur throughout any year. Continuing concentrations that significantly exceed the Guideline Values require investigation and rectification.
The information assessed in this report is available on the NSW Health water database, and uses the current National Health and Medical Research Council Drinking Water guidelines as the reference for the analytical comparisons. . The results included in this report are from 1st January 2005 to the time of writing, mid-November 2008.
References
NSW Department of Health Drinking Water Database 2008 http://www3.health.nsw.gov.au/waterqual/samples/register.cfm.
NH&MRC and NRMMC 2004. Australian Drinking Water Guidelines. National Water Quality Management Strategy.
http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm
