Gundagai
Indicator: Drinking Water Quality
Results for this indicator are also available for [an error occurred while processing this directive]
Summary
The Gundagai drinking water supply is of excellent and consistent quality.
Introduction
Drinking water quality is monitored as part of the 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 2004-2008 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
Gundagai is supplied from the Murrumbidgee River and treated at the Gundagai water treatment plant. This plant has full treatment facilities, and uses chlorine disinfection for the supply. The Gundagai supply is fluoridated. The supply provides water for 2,300 people in Gundagai Shire.
A total of 187 samples were assessed for E. coli, and over the four years no samples showed the presence of the organisms. This indicates a consistently excellent quality supply.
Thirty-eight samples were assessed for pH and three samples showed a small elevation upto pH 9.0 (mean 7.8), compared to the recommended range of pH 6.5-8.5, which is of no health significance. Seven samples were assessed for inorganic components. One sample showed aluminium slightly above Guideline Values, which is of no health significance.
About the data
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 E 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 1st January 2005 to mid-November 2008.
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.
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
