Lake hydrodynamic models are used by water utilities to provide an estimation of the conditions within a water storage. Increasingly, water utilities are employing a pathogen module to simulate the advection and dispersion of pathogens in source water. Lake model outputs provide forecasted pathogen concentrations across the water column of lakes and reservoirs, including at the offtakes of water treatment plants. This pathogen information, in combination with any monitored pathogen concentrations, provides important inputs to water quality experts to conduct quantitative microbial risk assessment.

The quality and outcomes of a lake modelling process depend on several critical steps, some of which are implicitly used by modellers, but which are often not adopted routinely or communicated widely as part of a quality assurance process. There is an emerging need in the drinking water supply industry for information and guidance on the appropriate use of lake models to support QMRAs. Ideally, the information is provided through a set of best practice guidelines that demonstrate a series of quality assurance principles and actions to ensure that model development, implementation and application represent best practice and are commensurate with the intended purpose. This project will identify, review, and communicate guidance on specific modelling steps, such as project administration, conceptual modelling framework, model evaluation metrics, and uncertainty analysis practice, and prepare consultative draft of the detailed best practice guidelines.

Source water protection underpins the safety and affordability of drinking water supplies where the prevention of water contamination provides greater surety than removal of contaminants. The Australian Drinking Water Guidelines emphasises the protection of source waters to the maximum degree possible as part of the multiple barrier approach to mitigate possible contamination.

Meanwhile, water utilities have been placed under increasing pressure to introduce or increase recreational access to drinking water catchments and water storages. There is also a lack of consensus around the impacts of different types of recreational access across Australia.

This project will summarise the current state of play of recreational access in Australia, report on the risks associated with different types of access, outline the types of cost benefit analyses that utilities can use when assessing recreational access, and promote a national understanding of risk to public health and water security.

The protozoan parasites, Cryptosporidium and Giardia represent a major public health concern of water utilities in developed nations. In Australia, marsupials, cattle and sheep are the dominant animals inhabiting water catchment areas and contribute a large volume of manure to catchments. Cryptosporidium fayeri, one of the main species identified in marsupials, was identified in a 29-year-old woman in Sydney in 2009 with identical subtypes found in marsupials in the area. There have also been reports of C. parvum and C. hominis (the most common species found in humans), in kangaroos, a wallaby, possums and bandicoots by independent groups, as well as high prevalence’s of zoonotic genotypes of Giardia in marsupials.

This project conducted a comprehensive study of genotypes of Cryptosporidium and Giardia present in marsupials, pre-weaned cattle and sheep and STP sites, over a three-year period to gain a more thorough understanding of the zoonotic risk these parasites pose to humans. In addition to cataloguing the genotypes present using next generation sequencing technologies, researchers also enumerated the numbers of Cryptosporidium and Giardia (oo)cysts present in samples and conducted a survey of farming practices to determine if particular management practices were associated with a higher or lower prevalence of zoonotic genotypes in pre-weaned cattle and sheep.

Stormwater and treated wastewater can contain infectious pathogens. The Australian Guidelines for Water Recycling (AGWR) require that these are removed during recycling, and that recycling processes pass “Quantitative Microbial Risk Assessments” (QMRA). The problem is that these QMRA’s are often based on estimates. This research further developed methods (begun in WaterRA project 3002) to generate real-world measurements and data relevant to firefighters and domestic users because there are concerns that small amounts of recycled non-potable water might be inadvertently ingested. To test this, a harmless chemical, cyanuric acid, was added to safe water, then twenty-six volunteers used it, and a domestic high-pressure sprayer, to clean a full-sized model car for 10 minutes. The volunteers then collected their own urine for the next 24h because if this test-water is ingested, the cyanuric acid can be measured in the urine. From this it was discovered that the volunteers ‘drank’ an average of 0.13mL. This led to the conclusion that the conservative estimates in the AGWR currently protect domestic non-potable recycled water users, but that prolonged and/or high intensity occupational use of high-pressure sprays should be investigated further.