Eurobodalla
Indicator: Drinking Water Quality
Results for this indicator are also available for [an error occurred while processing this directive]
Please note: Text or data highlighted in this colour represent an update to this indicator for the period 2008/09.
What the results tell us for Eurobodalla
Drinking water quality is monitored as part of the New South Wales (NSW) drinking water monitoring programme, 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 2004-08 is prepared from examination of this data, to illustrate the quality aspects of the water supplied for domestic consumption in the Shire. The Shire uses both public and private water supplies, but only those supplies recorded on the health database are available for comment in this report.
Quality of the water supplied
Data are available for Eurowater, the overall Shire drinking water supply, and for the independent sources forming the supply. These are drawn from the Buckenboura River, Deep Creek Dam, Dromedary Weir. Apart from in emergency drought situations the Dromedary weir supply – whilst still part of the system is not used. Moruya River and Tuross River. Deep Creek Dam, Buckenboura River and Moruya River supply water to the whole shire. The Tuross River supplies water to Narooma and the villages south including Bodalla. The Dromedary Weir supplies drinking water to Central Tilba in cases of emergency drought conditions.
The population supplied is 34,660, with the largest numbers in Batemans Bay (10,200) Narooma (4,300) and Moruya (3,300). Thirty five parameters of water quality were measured on 46 samples, E. coli on 1,416 samples, free chlorine on 1,380 and pH and total chlorine on 300-400 samples.
Eurowater. Eurobodalla Drinking Water Supply
A total of 1,416 samples were assessed for E. coli, and three samples showed the presence of the organisms. The highest count was two organisms per 100mL water and the instances were in 2005, 2006 and 2008. This represents a negligible level of microbial contamination.
Between 1 July 2008 and 30 June 2009 a total of 353 samples were assessed for E. coli. No samples tested positive for the presence of E.coli. This achieves compliance with the Australian Drinking Water Guideline 2004 (ADWG) with respect to the microbial indicator organism.
Three hundred and sixty three samples were tested for pH, with 44 samples outside of the Australian Drinking Water Guidelines (ADWG) recommended range of 6.5-8.5. The range of results was 5.5 to 9.5 with a median value of 7.2 indicating a generally satisfactory level of alkalinity.
Inorganic components were measured in 15 samples, and three indicated iron concentrations above the ADWG aesthetic criteria values. The highest was 0.5 mg/L, and the median concentration 0.2mg/L which is below the ADWG recommended value of 0.3mg/L. All other parameters met the ADWG health and aesthetic based criteria.
About the data
Interpreting the data
In 2004 the NHMRC 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 results included in this report are from 1 January 2005 to the time of writing, mid-November 2008.
The information assessed in this report is available on the NSW Health water database, and uses the current NHMRC Drinking Water guidelines as the reference for the analytical comparisons.
References
NSW Department of Health Drinking Water Database 2008 http://www3.health.nsw.gov.au/waterqual/samples/register.cfm.
NHMRC and NRMMC – see National Health and Medical Research Council and Natural Resource Management Ministerial Council
National Health and Medical Research Council and Natural Resource Management Ministerial Council 2004. Australian Drinking Water Guidelines. National Water Quality Management Strategy. http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm
