Goulburn Mulwaree
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 Goulburn Mulwaree
Excellent overall water quality over the reporting period. Rather ‘hard’ water in all three supply systems, which has no health implications. The single spike in metal content for one sample may indicate some release from a quarry or similar site.
Drinking water quality is monitored as part of the New South Wales (NSW) drinking water monitoring programme, and detailed results were 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 Council area. The Council area 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 the Goulburn, Marulan and Run-o-Waters supplies, which provide water to approximately 23,000 people in Goulburn City, 600 in the Marulan supply and 60 in Run-o-Waters.
Goulburn (Wollondilly River treatment works)
This water treatment plant provides full treatment, chlorine disinfection and fluoridation of the supply. Daily samples were analysed for fluoride, and showed consistent and accurate fluoride control.
A total of 393 samples were assessed for E. coli, and one sample showed the presence of the organisms. The number detected was 15 organisms per 100mL in a sample on 9 June 2007. No organisms were counted in samples prior to or after this sample that year. None were detected to date in 2008. This shows a consistently good microbiological quality of the water supply, with that single exception.
Forty-seven samples were assessed for inorganic components. The outstanding characteristic of this water supply is hardness. This is measured as calcium carbonate, which exceeded the National Health and Medical Research Council (NHRMC) recommendation of 200mg/L on 21 occasions over 2005, 2006, 2007 and 2008. The recommended level is based on lime scaling of hot water systems, and has no health implications.
Aluminium, lead and nickel exceeded the Guideline Values on two occasions, and iron once. In particular on 1 August 2006 there was a single spike of metals in the supply in which lead reached 0.014mg/L, compared with a Guideline Value of 0.01, iron reached 0.43 mg/L compared with a guideline value of 0.3 mg/L and aluminium 0.44 compared to a guideline value of 0.2mg/L. This sample also recorded a raised turbidity, which may imply a release of water from an old mine site or quarry. The raised nickel was observed in June 2005 and 2007, both as single events, one of which coincided with raised lead concentration. None of these transient concentrations present a health risk. Overall an excellent quality water supply, though rather ‘hard’ water.
Marulan area supply
This supply is filtered and chlorinated for disinfection. One hundred and ninety eight samples were examined for E. coli and one sample showed two organisms detected. Inorganic components did not show any exceeding the Guideline Values, except for total hardness with a three samples above the recommended concentration. An excellent quality drinking water supply.
Run-o-Waters
Eighteen samples were assessed for E. coli, and none were found. The inorganic components were measured in three samples, and the only comment is that the water is rather ‘hard’, but only marginally above the level suggested by the NHMRC on the basis of lime scaling of hot water systems. An excellent quality water supply.
About the data
Interpreting the data
In 2004 the NHRMC 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.
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 assessing 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 NHMRC Drinking Water guidelines as the reference for the analytical comparisons. The results included in this report are from 1 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.
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
