Supporting the implementation of drinking water management systems in New South Wales, Australia.

Since 2010, New South Wales (NSW) Health has assisted local water utilities to develop and implement risk-based drinking water management systems based on the Australian Drinking Water Guidelines Framework for Management of Drinking Water Quality. This support has benefited regional communities, and especially smaller utilities, by helping to identify and control risks. NSW Health's support projects have resulted in statistically significant improvements across many elements of drinking water management system implementation. Through this program of support, NSW Health has identified possible infrastructure and operational needs and assessed implementation of drinking water management systems. In parallel, NSW Health has worked to assess the risk from Cryptosporidium in drinking water supplies and to develop a formal audit program. Findings from the NSW Health support program informed the development of two NSW Government programs and the commitment of more than $1 billion to help local water utilities address public health and other critical needs. The introduction of risk-based drinking water management systems has driven incremental improvement in drinking water quality management across the state of NSW.

Supply system factors associated with microbiological drinking water safety in regional New South Wales, Australia, 2001-2007.

AIM: To determine factors associated with microbiological safety of public drinking water systems in regional New South Wales (NSW), Australia. METHOD: We analysed 107,000 end-user drinking water samples for an association between detection of Escherichia coli and drinking water system features, sample year and season using NSW Health Drinking Water Monitoring Program data, 2001-2007. We used negative binomial generalized estimating equations with adjustment for autocorrelation and clustering. RESULTS: We detected E. coli in over 2% of samples from 40% (129/323) of systems. E. coli detection was significantly more common in earlier years and during summer (p<0.001). On multivariate analysis E. coli detection was significantly associated with smaller systems; watercourse sources; no disinfection or disinfection with ultraviolet only; and higher post-treatment mean turbidity (all p< or =0.01). Detection was most strongly associated with lack of disinfection (incidence rate ratio 12.6, p<0.001) and smaller supply systems (1% reduction in E. coli detection for each 1,000 person increase in supply population, p=0.004). Ultraviolet disinfection alone was the least effective disinfection method (p<0.001). CONCLUSION: Even in developed countries, drinking water systems without disinfection or serving small populations appear vulnerable to the effects of faecal contamination, which presents a risk of waterborne disease outbreaks.

Implementation of quantitative microbial risk assessment (QMRA) for public drinking water supplies: Systematic review.

In the more than 15 years since its introduction, quantitative microbial risk assessment (QMRA) has become a widely used technique for assessing population health risk posed by waterborne pathogens. However, the variation in approaches taken for QMRA in relation to drinking water supply is not well understood. This systematic review identifies, categorises, and critically synthesises peer-reviewed and academic case studies of QMRA implementation for existing distributed public drinking water supplies. Thirty-nine English-language, peer-reviewed and academic studies published from 2003 to 2019 were identified. Key findings were synthesised in narrative form. The overall designs of the included studies varied widely, as did the assumptions used in risk calculation, especially in relation to pathogen dose. There was also substantial variation in the degree to which the use of location-specific data weighed with the use of assumptions when performing risk calculation. In general, the included studies' complexity did not appear to be associated with greater result certainty. Factors relating to pathogen dose were commonly influential on risk estimates whereas dose-response parameters tended to be of low relative influence. In two of the included studies, use of the 'susceptible fraction' factor was inconsistent with recognised guidance and potentially led to the underestimation of risk. While approaches and assumptions used in QMRA need not be standardised, improvement in the reporting of QMRA results and uncertainties would be beneficial. It is recommended that future authors consider the water supply QMRA reporting checklist developed for the current review. Consideration of the broad types of uncertainty relevant to QMRA is also recommended. Policy-makers should consider emergent discussion on acute microbial health-based targets when setting normative guidelines. The continued representation of QMRA case studies within peer-reviewed and academic literature would also enhance future implementation. Further research is needed on the optimisation of QMRA resourcing given the application context.

Water safety plans: planning for adverse events and communicating with consumers.

A wide range of microbial and chemical characteristics in drinking water have the potential to affect human health. However, it is not possible or practical to test drinking water for all potentially harmful characteristics. If drinking water is contaminated, people may already be exposed by the time test results are available. The 'boil water alert' issued in Sydney, Australia in 1998 following the detection of Cryptosporidium and Giardia in the finished water supply, highlighted the uncertainties associated with the public health response to test results. The Sydney experience supports the international consensus that a preventive risk-management approach to the supply of drinking water (manifesting as water safety plans (WSPs)) is the most reliable way to protect public health. A key component of a comprehensive WSP is that water suppliers and health authorities must have plans to respond in the case of water contamination and/or outbreaks. These plans must include clear guidance on when to issue warnings to consumers, and how these warnings are to be communicated. The pressure on health authorities to develop clear and systematic boil-water guidance will increase as utilities all over the world develop their WSPs.

Ensuring safe drinking water in regional NSW: the role of regulation.

In regional and rural areas of NSW, drinking water is provided by 107 local water utilities serving a total population of some 1.7 million and operating 323 water supply systems. NSW Health exercises public health oversight of these regional water utilities through the NSW Health Drinking Water Monitoring Program, which provides guidance to water utilities on implementing elements of the Australian Drinking Water Guidelines 2004, including drinking water monitoring.

Safe drinking water in regional NSW, Australia.

The New South Wales (NSW) Public Health Act 2010 requires water suppliers to implement a drinking water quality assurance program that addresses the 'Framework for management of drinking water quality' in the Australian drinking water guidelines. NSW Health has recognised the importance of a staged implementation of this requirement and the need to support regional water utilities. To date, NSW Health has assisted 74 regional utilities to develop and implement their management systems. The Public Health Act 2010 has increased awareness of drinking water risk management, and offers a systematic process to identify and control risks. This has benefited large utilities, smaller suppliers, and remote and Aboriginal communities. Work is continuing to ensure implementation of the process by private suppliers and water carters.

Spatio-temporal variation in trihalomethanes in New South Wales.

AIM: This paper describes the spatio-temporal variation of trihalomethanes in drinking water in New South Wales, Australia from 1997 to 2007 METHOD: We obtained data on trihalomethanes (THMs) from two metropolitan and 13 rural water utilities and conducted a descriptive analysis of the spatial and temporal trends in THMs and the influence of season and drought. RESULTS: Concetrations of monthly THMs in the two metropolitan water utilities of Sydney/Illawarra (mean 66.8 µg/L) and Hunter (mean 62.7 µg/L) were similar compared to the considerable variation between rural water utilities (range in mean THMs: 14.5-330.7 µg/L). Chloroform was the predominate THM in two-thirds of the rural water utilities. Higher concentrations of THMs were found in chlorinated water distribution systems compared to chloraminated systems, and in distribution systems sourced from surface water compared to ground water or mixed surface and ground water. Ground water sourced supplies had a greater proportion of brominated THMs than surface water sourced supplies. There was substantial variation in concentration of THMs between seasons and between periods of drought or no drought. There was a moderate correlation between heavy rainfall and elevated concentrations of THMs. CONCLUSION: There is considerable spatial and temporal variation in THMs amongst New South Wales water utilities and these variations are likely related to water source, treatment processes, catchments, drought and seasonal factors.