Boorowa
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 Boorowa
The drinking water supply was of consistently good quality with two exceptions in December 2007 that have not recurred since.
Quality of the water supplied
A full treatment plant, with all normal processes and, in addition, granular activated carbon, supplies the water. The supply provides water for 1,300 people. Water is sourced from the Boorowa River.
A total of 165 samples were assessed for E. coli, and two samples showed the presence of the organisms. In 2007 one sample on 8th Dec contained 19 organisms per 100mL and a second on 10th Dec contained 59 organisms per 100mL water. This contamination had cleared to zero in a sample collected the following day. Prior to these events the free chlorine concentration in the water was unusually low (0.07 mg/L), which may have accounted for the organisms in the water supply. After these events the free chlorine was at low (0.13 mg/K) but higher concentrations. The NH&MRC quote that water authorities may need to exceed the odour threshold of 0.6mg/L in order to maintain effective residual chlorine for disinfection.
There were no inorganic components of the water supply exceeding the Guideline Values that were of health significance. However chloride was relatively high, which may result in a salty taste.
About the data
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 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.
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 results included in this report are from 1st 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 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
