The environmental conditions which cause blue-green algae (cyanobacteria) blooms vary according to location, the climate, and other attributes of aquatic ecosystems. This variety has made it difficult to develop one broadly applicable predictive model for cyanobacterial blooms. Water utilities monitor source waters to implement cyanobacterial risk management programmes but there are no standard protocols while limited information transfer between utilities has prevented the identification of management strategies that do or do not work. This research reviewed literature about early warning systems (Almuhtaram et al., 2021) and source control strategies, conducted a survey of 35 utilities in America and Canada (74%) and Australia (Kibuye et al., 2021) and evaluated selected control strategies. These different types of information were synthesised into decision trees within an overarching guidance document. It was concluded that a 3-tier framework to detect algal blooms which monitored biological activity, then confirmed the identification of cyanobacterial genes and associated metabolites gave sufficient early warning, while multi-barrier control strategies gave field-scale efficacy and enabled timely responses.

Burkholderia pseudomallei is a bacteria that is widespread in SE Asia and northern Australia, where there are an average of 16 cases per 100,000 people. This research found that water samples collected in and around Cairns from June to September did NOT contain Burkholderia pseudomallei and led to the conclusion that the risk of infection is much lower than in Darwin or Townsville.

Water treatment plants (WTP) produce safe drinking water that does not contain harmful microscopic pathogens, but subsequent pipe-leaks or valve or hydrant malfunctions en route to the customers tap increase the risk of pathogens entering the public water supply. International studies indicate a small increase in gastroenteritis for some customers downstream of mains pipeline breaks and repairs. This research compiled Australian cases and found that health risks are probably lower than international examples for many reasons, including that sewer and drinking water pipes tend not to be laid in the same trench. After improving understanding regarding the contamination risks of renewal and water main repair activities in Australia, a control and management framework was produced in accordance with the ADWG. This gives guidance to water utilities about staff training, risk assessment and optimal documentation processes for dynamic site evaluations and repair control mechanisms.

Although a cluster of customer complaints can identify specific water quality issues such as a dirty water event, it is more difficult to understand the extent of general customer satisfaction with water quality and taste. The Final Report for this project includes four printable water quality Factsheets for the general public which explain tastes and odours, fluoridation, and disinfection. The Report also includes the protocols and texts for two customer engagement techniques: Blind Taste Testing and Systematic Taste Testing; as well as a comprehensive customer survey instrument to assess perceptions of drinking water quality. These can be downloaded to electronic mobile devices and used to direct face to face customer engagement with the tastes and odours of different types of potable water. The scoresheet links to a rating spreadsheet that collates results and generates graphical representations of customer acceptance of water sample taste. These tools have been used to assess customer satisfaction with water quality at large events including National Water Quality week or Utility information days.

Water treatment plant operators remove cyanobacteria and the toxins they produce from source waters but calculating the amount of treatment needed for effective removal is difficult, particularly in bloom conditions when cyanobacterial cell numbers and toxins change quickly. Current cell counting and toxin measurement can take hours or days to complete, and the results are not available quickly enough to help treatment plant operators respond to changing conditions. There is a need for a real-time method that gives instant results. This research examined the utility of fluorometers; probes that emit light that is ‘reflected’ back at different wavelengths by living cells and other matter in the water and is detected by the fluorometer. It was found that when only one species of cyanobacteria was present, there was a good correlation between the fluorescent signal and cell number, particularly when source waters were clear and not cloudy. Cell numbers did not relate well to levels of toxins or taste and odour compounds. When fluorometers were installed in 13 water treatment plants the correlation between cyanobacteria cell numbers and fluorometer signals was validated, and this led to the conclusion that fluorometers can give early warning of blue-green algae blooms.

Microscopic pathogens in drinking water pose a risk to public health. In Australia, chlorine or chloramine are used to inactivate these pathogens, to disinfect drinking water and prevent widespread outbreaks of debilitating illness in large populations. Although largely successful, problems arise when drinking water is contaminated by pathogens after being disinfected in the treatment plant but before reaching the customer. A variety of situations cause this, one being small pipe leaks which become a route for soil micro-organisms to get into drinking water. To prevent pathogen contamination in pipe networks, higher levels of disinfectants can be added at the treatment plant, or secondary disinfection can be administered in the pipe network. This research project produced a guidance manual which explains how to maintain and monitor effective disinfection levels in post-treatment pipelines, and the major challenges to maintaining effective disinfection.

‘Microbial source tracking’ (MST) is a technique that aims to identify the animal that excreted faeces and polluted water. There are a number of ways to do this, but the problem is that no one method accurately identifies the origins of faecal pollution in environmental water samples. This research found that faeces could be stored in a freezer or a laboratory -80°C cold-store for up to a month without changing the relative numbers of the different types of bacteria in the samples of faeces. Up to seven faeces samples from different animals were mixed together and examined using 17 techniques to identify the original animals. Three of the most accurate and reliable methods used mitochondrial DNA, the analysis of a bacterial enzyme sequence (beta-glucuronidase), and specific DNA sequences form bacteria known to come from humans, horses and cows. These three types of tests were selected for inclusion in a ‘Toolbox’ from which a combination of methods will allow accurate and reliable management of faecal contaminants in source waters.

Water utilities lack the information they need to implement risk-based adaptation and planning strategies that incorporate climate change. This research addresses this problem by modelling the effects of climate change on reservoirs in three climate zones: temperate, humid tropical and Mediterranean. By integrating different modelling approaches it was concluded that increased temperatures will increase water stratification; the differences in water temperature that occur with depth. This is important because the duration and type of stratification affects the storage and release of substances from reservoir floors and this in turn affects blue-green algal blooms and water quality. The integrated modelling approach developed in this project can be applied to the management of contaminants running off the catchments and for future risk assessment. This information will also support the development of business cases for targeted catchment interventions.

Cryptosporidium, a microscopic single-cell parasite, forms an “oocyst” with a resistant outer layer analogous to an eggshell. Oocysts survive for a long time in the environment but UV in sunlight, and high temperatures that cause desiccation, kill them. If a mammal drinks water containing live oocysts, they embed in the gut wall and continue their lifecycle until eventually many more oocysts are excreted. There are 26 species of cryptosporidium but only five infect humans, and two; Cryptosporidium hominus and Cryptosporidium parvum, cause approximately 95% of all human infections. C. hominus occurs only in humans, but C. parvum is also found in cattle, sheep, and other animals. The problem is that human-infecting oocysts are excreted by animals in catchments and rain can wash live oocysts into water reservoirs. This research collated peer-reviewed published literature, and information and data collected by the water industry, then characterised the distribution of different Cryptosporidium species in Australian catchments. This led to recognition of a research need to track and predict live and dead oocyst transport during different weather events, and to model and evaluate catchment management initiatives such as excluding cattle from reservoir areas.

The ADWG 2011 lacked objective, quantifiable criteria for measuring pathogen removal from source waters. The WHO requires that health-based targets (HBTs) are used to ensure safe drinking water. HBTs can be set by making ‘Disability Adjusted Life Year’ (DALY) calculations which incorporate information about a population; the average Australian lifespan and the impact of infection on the length of a healthy life. Pathogen levels in water that correspond to micro-DALYs with minimal population-level effects are too low to be detectable by existing tests. This problem is addressed by calculating ‘log removal values’ (LRVs). Pathogens can be measured in source and treated water after the application of a defined method. When 90% of the pathogen is removed, the LRV equals 1, while 99% removal has an LRV of 2. HBTs incorporate LRVs, which are based on objective, quantifiable criteria, to reduce pathogen loads to levels that correspond to acceptable Australian micro-DALY levels. This research collated existing datasets about pathogens in source waters and the efficiency of their removal by treatment plants around Australia. From this, default pathogen levels for a range of Australian source waters and climate events, and LRVs for different treatment methodologies were obtained.