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Seasonality Index (SI) is commonly used to define rainfall variability within a year for a locality, which has got significant impact on the water resources planning and management. Both the longer periods of dry and wet conditions are reflected by SI value. As SI is calculated using historical rainfall data, a historical average value is represented for a locality. However, with the emerging impacts of climate change SI values based on historical data are likely to change. This paper presents expected changes in future SI values for the largest city of Australia (Sydney) based on projected future rainfall scenarios for the city. The paper further illustrates potential water savings through rainwater tanks under projected climate change scenarios using an earlier developed daily water balance model, eTank. For the simulations of potential water savings through rainwater tanks, projected daily rainfall data was collected from Australian government data portal for four stations within Sydney. Future potential rainwater savings efficiencies were correlated with the corresponding SI values. It is found that such correlation closely matches with an earlier developed correlation using past historical data, however the future water savings efficiency will be slightly lower than the past water savings efficiency. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) systems can be used to produce drinking water in rural communities, particularly in developing countries that lack a clean drinking water supply. Most previous research has focused on the application of RWH systems for individual urban households. This paper develops a yield-after-spillage water balance model (WBM) which can calculate the reliability, annual drinking water production (ADWP) and benefit–cost ratio (BCR) of a community-scale RWH system for rural drinking water supply. We consider multiple scenarios regarding community aspects, including 150–1000 users, 70–4800 kL rainwater storage, 20–50 L/capita/day (LCD) drinking water usage levels, local rainfall regimes and economic parameters of Australia (developed country) and Vietnam (developing country). The WBM analysis shows a strong correlation between water demand and water supply with 90% system reliability, which allows both Australian and Vietnamese systems to achieve the similar capability of ADWP and economic values of the produced drinking water. However, the cost of the Vietnamese system is higher due to the requirement of larger rainwater storage due to larger household size and lower rainfall in the dry season, which reduces the BCR compared to the Australian systems. It is found that the RWH systems can be feasibly implemented at the water price of 0.01 AUD/L for all the Vietnamese scenarios and for some Australian scenarios with drinking water demand over 6 kL/day. [ABSTRACT FROM AUTHOR]

Exponential growth of water demand and a decrease in usable freshwater due to various climate, environmental and anthropogenic events make rainwater harvesting a useful practice. According to Australian health regulations, drinking rainwater is low risk, if the roof catchment, collection system and storage are well maintained. The CSU Engineering building, which has received an architectural award for its sustainable design, produces its drinking water (3.7 L/person/day) within the premises. Rainwater is collected from the roof catchment, stored outside the building and treated on demand at a fully transparent water treatment plant installed at the entrance of the building. The water treatment facility is fully powered by solar panels installed on the roof. The treatment process consists of several operations, including aeration, sand filtration, GAC adsorption and UV disinfection. The performance of the CSU Engineering water treatment plant for the past 30 months is discussed in this paper. Primary and secondary water quality parameters of treated water were well within Australian drinking water quality standards and showed better results than municipal water available in the host town. The aeration unit improved secondary water quality standards (odor and taste) and the adsorption process was effective for elimination of metals. The result of this experiment indicated that this process could be a promising solution for providing safe drinking water in remote Australia, including sessional demands in rest areas and caravan parks. [ABSTRACT FROM AUTHOR]

Continued population growth, and climate change are placing stress on many of the world's water sources and this often manifests in environmental damage to rivers and wetlands. Most of the published literature around allocating more water to the environment considers trade-offs with agriculture. In contrast this study focusses on scenarios for different potable water supplies in cities and thus adds a novel perspective on the value of riverine restoration. This study sheds light on urban households' willingness to pay for more water to be allocated to the environment where it directly competes with their own water demands. The study uses two stated preference techniques (choice modelling and best-worst scaling) to establish the value of environmental water and the motivations for households paying for an increase in environmental water reserves. The study is set in Australia's fastest growing city, Melbourne, although the approach and method have implications for other developed-world settings. The paper also offers practical advice on the management of water allocated for different uses. Overall, the results indicate a positive and significant willingness to pay by households for additional water entitlements. Importantly, this provides a benchmark for contemplating the costs and benefits of activating alternative water supplies, such as desalination, to free up rainwater for environmental purposes. • Urban residents are willing to make non-trivial payments for water for the environment. • Few respondents object to the reassignment of water to environmental uses. • The value residents place on additional water for urban waterways is identified. • Improvements in water quality and preserving platypus is important to residents. [ABSTRACT FROM AUTHOR]

Rainwater tanks are a fundamental component of integrated water cycle management, but the quality of harvested water is little understood and is potentially affected by many factors such as roofing material, site temperature, frequency of tank use, and surrounding land use. There has been limited study of the first flush, overflow water and harvested water quality from rainwater tanks in Australia. This paper presents the water quality results of a yearlong data collection and analysis study involving five rainwater tanks located in Western Sydney, Australia. The results show that tank water quality was impacted by the construction materials used to fabricate both the tanks and roofs. Furthermore, the overflow and first flush water quality were found to be of a lower standard than the tank samples, with implications for the cleaning of the first flush device and overflow diversion. Finally, the issues identified with the maintenance of the tanks are highlighted and discussed. [ABSTRACT FROM AUTHOR]

Fit-for-purpose potable source substitution of appropriate water end uses with rainwater or recycled water is often essential to maintain water security in growing urban regions. This paper provides the results of a detailed supply-demand forecasting review of a unique tri-supply (i.e., potable, A+ recycled and rain water sources reticulated to household) urban water scheme located in Queensland, Australia. Despite the numerous benefits of this scheme, system efficiency (e.g., reduced demand levels, water treatment, low chemical and energy use) and economic viability (i.e., capital and operating costs per kL of supply) aspects need to be considered against derived potable water savings. The review underpinned the design of a framework to enhance the schemes supply-demand balance and reduce the unit cost of alternative source supplies. Detailed scenario and sensitivity analysis identified the possibility of a refined scheme design, whereby the A+ recycled water supply would be reticulated to the cold water input tap to the washing machine, and the rain tank that originally supplied this end use be removed from future constructed households. The refined scheme design enhances the present recycled plant utilisation rate and reduces the cost to home owners when building their dwelling due to the removed requirement to install a rain tank to indoor end uses; such actions reduce the overall unit cost of the scheme. [ABSTRACT FROM AUTHOR]

We have only rudimentary understanding of the complex and pervasive connections between water and energy in cities. As water security now threatens energy and economic security, this is a major omission. Understanding the water-energy nexus is necessary if we want to contribute to solving water and energy issues simultaneously; if we want to stop moving problems from one resource dimension to another. This is particularly relevant in the Australian context where energy use for water supplies is forecast to rapidly escalate, growing around 300% from 2007 levels, by 2030. This paper presents a literature review with an aim of characterising the research to date with a particular focus on cities, the major centres of consumption and growth. It systematically analyses a wide range of papers and summarises the diverse objectives, dimensions, and scale of the research to-date together with knowledge gaps. There are many major gaps. These include energy use associated with water in industrial and commercial operations as well as socio-political perspectives. A major gap is the lack of a unifying theoretical framework and consistent methodology for analysis. This is considered a prerequisite for quantitative trans-city comparisons. [ABSTRACT FROM AUTHOR]

A Water Sensitive City is now commonly acknowledged best practice for designing the cities of the future. In Australia, the National Water Initiative has allocated high priority towards offering insight into successful water sensitive urban development projects, to facilitate capacity building within the industry. This paper shares innovative water sensitive projects implemented at Kogarah City Council, in Sydney. Four key projects are discussed, demonstrating how stormwater, rainwater and wastewater can be incorporated into decentralised water systems to offer sustainable water management of the future. The case studies included in the paper highlight Kogarah's journey towards the Soft Path for Water Management. [ABSTRACT FROM AUTHOR]

Abstract: Australia is currently facing a serious water crisis. Saving water is not the government''s solo effort, it also requires support from individual households. The use of rainwater tanks for rainwater storage has been highly recommended for both outdoor and indoor uses. This paper investigates cost effectiveness on the use of rainwater tanks for Australian residential environment. Seven cities are examined in this paper, including Gold Coast, Brisbane, Melbourne, Sydney, Adelaide, Perth and Canberra. Cost for installing and operating rainwater tanks and cost from alternative water sources including building additional dams and desalination plants are compared. It is found that using rainwater is an economical option for households in Gold Coast, Brisbane, and Sydney. Recommendations of suitable tank sizes for different household environments are also proposed. [Copyright &y& Elsevier]

Rainwater tanks are increasingly being implemented as part of the integrated urban water management paradigm where all sources of water, including potable, stormwater and recycled, are considered eligible to contribute to the urban water supply. Over the last decade or so, there has been a rapid uptake of rainwater tank systems in urban areas, especially in Australian cities, encouraged through financial incentives, but more importantly, from change in residential building codes effectively mandating the installation of rainwater tanks. Homes with rainwater tanks in Australian cities have increased from 15% to 28% over six years to 2013. These building codes specify certain rainwater tank specifications to achieve a stated rainwater use, and hence potable water savings. These specifications include minimum rainwater tank size, minimum connected roof area, plumbing for internal supply for toilets and washing machines, and external supply for garden watering. These expected potable water savings from households are often factored into regional strategic water planning objectives. Hence if rainwater tanks do not deliver the expected saving due to sub-standard installation and/or poor maintenance, it will have an adverse impact on the regional water plan in the longer term. In this paper, a methodology to assess the effectiveness of a government rainwater tank policy in achieving predicted potable water savings is described and illustrated with a case study from South East Queensland, Australia. It is anticipated that water professionals across the globe should be able to use the same methodology to assess the effectiveness of similar rainwater policies, or indeed any other distributed water saving policy, in their local planning communities. [ABSTRACT FROM AUTHOR]

Due to climate change, freshwater supply will be limited at many locations around the globe. Rainwater harvesting (RWH) has emerged as an alternative and sustainable freshwater source. In this study, the impacts of climate change on water saving as well as the reliability of a RWH system are investigated using data from eight Australian capital cities. Both historical and projected rainfall data were incorporated into a daily water balance model to evaluate the performance of a RWH system in relation to its reliability, water savings and scarcity. Indoor (toilet and laundry), outdoor (irrigation) and combined (indoor plus outdoor) water demands were considered for a 5 m3 tank size. It has been found that in the future period, the water savings and reliability of a RWH system will reduce slightly across the selected cities. Different capital cities of Australia will experience different level of performance for a RWH system depending on their locations, water uses and seasons. The findings of this study will be useful to water authorities and policy makers to plan for a sustainable RWH system under changing climate conditions. [ABSTRACT FROM AUTHOR]

Summary: Melbourne is facing a severe drought having its 12th consecutive below average rainfall year. Water authorities have been forced to impose rigorous water restrictions including voluntary per capita water use targets after more than 20years of unrestricted water supply. The current severe drought and dwindling water resources have accelerated the use of alternative water sources including domestic rainwater. There is a large variation in average annual rainfall in the Greater Melbourne area ranging from 1050mm in the east to 450mm in the west. Hence, there is a significant difference in the tank size required in the west and the east of Melbourne to meet a similar demand and to provide the same supply reliability. The paper presents a novel methodology and a relationship for optimal sizing of rainwater tanks considering the annual rainfall at the geographic location, the demand for rainwater, the roof area (catchment area) and the desired supply reliability. The characteristic of the developed dimensionless curve reflects these variables and paves the way for developing a web based interactive tool for selecting the optimum rainwater tank size. [Copyright &y& Elsevier]

Although most Australians receive their domestic supply from reticulated mains or town water, there are vast areas with very low population densities and few reticulated supplies. In many of these areas rainwater collected in tanks is the primary source of drinking water. Heavy metals have recently become a concern as their concentration in rain water tanks was found to exceed recommended levels suitable for human consumption. Rainwater storage tanks also accumulate contaminants and sediments that settle to the bottom. Although not widely acknowledged, small amounts of contaminants such as lead found in rain water (used as drinking water) may have a cumulative and poisonous effect on human health over a life time. This is true for certain factors that underlie many of the chronic illnesses that are becoming increasingly common in contemporary society. The paper reports on a study which is part of a project that aims to develop a cost effective in-line filtration system to improve water quality in rainwater tanks. To enable this, the characteristics of rainwater need to be known. One component of this characterization is to observe the effects of the first flush on a rainwater tank. Samples of the roof runoff collected from an urban residential roof located in the Sydney Metropolitan Area in the initial first few millimetres of rain were analysed. The results show that bypassing the first 2mm of rainfall gives water with most water quality parameters compliant with the Australian Drinking Water Guidelines (ADWG) standards. The parameters that did not comply were lead and turbidity, which required bypassing approximately the first 5mm of rainfall to meet ADWG standards. Molecular weight distribution (MWD) analysis showed that the concentration of rainwater organic matter (RWOM) decreased with increasing amount of roof runoff. [ABSTRACT FROM AUTHOR]

Rainwater is a traditional but under-utilized water resource that has today had a resurgence due to the worldwide water crisis. This paper demonstrates the outcomes of research on the feasibility of rainwater use in high-rise residential envelopes for four Australian cities of Melbourne, Sydney, Perth and Darwin. Different climate patterns and various levels of water demand management were established for determination of storage dimensions; annual tank water use; reduction in both imported water flow and stormwater disposal; and water spillage from tanks. High level water demand management was a profoundly effective tool for reducing potable water supply, especially in combination with rainwater use. The economic feasibility of rainwater use systems were estimated; with Sydney having the shortest payback period compared to other cities either both with 3A rated appliances (8.6 years) or 5A ones installed (10.4 years). That was due to the higher and more consistent rainfall in Sydney. An outcome of this study was that Sydney was likely most suited to rainwater use, followed by Perth, Darwin, and then Melbourne. The objective of this study was to fill in the gap in estimating feasibility of rainwater use in various Australian cities. This investigation endeavors to provide assistance to water authorities and urban planners of Australian cities with the consideration of the potential of rainwater harvesting. [Copyright &y& Elsevier]

Due to significant weather variabilities of rainfalls, potential water savings through rainwater tanks are expected to vary significantly. Moreover, within some large cities, significant spatial variations are reported. With the emerging impacts of climate change, existing weather and spatial variabilities of potential water savings are also likely to be changed, which are unknown to the end-users. This paper presents the impacts of climate change on current weather and spatial variabilities of potential water savings for Adelaide, a large city in Australia. Future daily rainfall data was collected from a data portal provided by the Australian government derived through a statistical downscaling modelling. Projected daily rainfall data was fed to an earlier developed daily water balance model (eTank) to calculate water savings for three future periods; 2030–2050, 2055–2075 and 2080–2100. Three weathers (dry, average and wet) in each period were considered along with two climate change scenarios (RCP 4.5 and RCP 8.5) and two tank sizes (5 kL and 10 kL). It is found that varying outcomes without any general trend are expected depending on the projection scenario, period and weather condition. Contrary to the general perception, it is found that in several cases, the potential water savings are expected to increase compared to the current climate. Most of those expected increases in water savings are attributed to the projection scenario of RCP 4.5, in the near future and in dry years. In the far-future and with the projection scenario of RCP 8.5, most of the potential water savings are expected to decrease compared to the current climate. Regarding changes in spatial variability of water savings, it is found that the spatial variability will decrease in the near future, but will increase towards the far future. [ABSTRACT FROM AUTHOR]

There is little recognition in policy of existing adaptive capacities and experiments with alternate water systems in the Global North. Households that are self-sufficient for water present a space in which alternative relationships between water, comfort and convenience manifest. This article presents insights from a survey completed by 209 households that are self-sufficient for water in the Eurobodalla Shire, in regional New South Wales, Australia. The survey sought to understand practices, experiences, and perceptions of people who take responsibility for managing the capture, storage, consumption, and disposal of water at home. We found that most respondents rely on household-collected rainwater for all domestic purposes. Most drink rainwater, and many drink rainwater untreated. Respondents identified challenges of self-sufficiency, including running out of water, and infrastructure maintenance and failure. Notwithstanding these challenges, most respondents indicated that they enjoy living in a water self-sufficient home and would do so again in future. Most respondents moved to their non-mains water home for reasons other than being in control of water; adapting to water self-sufficiency was therefore a necessity rather than a choice. The results of this survey are significant as the water sector looks to diversify sources of domestic water to better adapt to uncertain futures. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) through household rainwater tanks has been increasingly recognized as a supplementary source of water in most urban cities. Previous studies indicated wide variations in annual water saving on residential water consumption. This study aimed to examine the factors causing these variations on the calculated savings of residential water use. The study involved the analysis of water consumption data collected by Yarra Valley Water (YVW) for 50 households with rainwater tanks and 50 without in Greater Melbourne, Australia. The results initially indicated an average annual saving of more than 4,600 L per year for an average household of 3.1 people; however, after considering seasonal variations, the estimated average potable water saving was more than 9,700 L per year. Further analysis revealed that properties without garden watering received more water saving than properties with garden watering (34,400–5,600 L per year, respectively). The results of this study are envisioned to lead to a better understanding of the effect of seasonal variations and local site conditions on the potential of RWH in integrated urban water management. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) has become a popular water saving and conservation means across the globe. In many cities, a pre-determined rainwater tank size is generally selected without a detail water balance modelling at the location on interest. However, to achieve maximum benefit from a RWH system at a given location, it is desirable to design the system based on the site specific conditions (e.g. local rainfall and loss characteristics) and other relevant design parameters. There have been limited studies on regionalization of RWH system, which can account for the spatial variability in rainfall, loss and water demand characteristics over a given region to provide site-specific design of RWH system. This paper presents a RWH regionalization approach to develop a set of design curves, which assist in the selection of an adequate RWH system at a given location. We use rainfall data from 159 rain gauges across the Greater Sydney region in Australia to develop and test the proposed regionalization approach. It has been found that there is a significant variation in rainfall characteristics across Greater Sydney region and that a common tank size across this region does not present an adequate solution. It has been found that a 5 kL tank can achieve a reliability (i.e. percentage of days the RWH can meet the given demand) of 31–93% for four people depending on the location in the Greater Sydney region and the types of water use. The developed regional design curves could result in increased water savings across Greater Sydney. The proposed regionalization approach can be adapted to other cities across Australia and the world which present a high rainfall gradient. • Water savings by rainwater harvesting at 159 locations in Sydney are evaluated. • Reliability of a rainwater tank is moderately correlated with mean annual rainfall. • A set of design curves is developed for Sydney to enhance rainwater harvesting. [ABSTRACT FROM AUTHOR]

To address concern regarding water sustainability, the Australian Federal Government and many state governments have implemented regulatory mechanisms and incentives to support households to purchase and install rainwater harvesting systems. This has led to an increase in rainwater harvesting in regional and urban Australia. This review examines the implementation of the regulatory mechanisms across Australia. In addition, the literature investigating the potential health consequences of rainwater consumption in Australia was explored. Studies demonstrated that although trace metals such as arsenic, cadmium, chromium, lead, and iron were present in Australian rainwater, these metallic elements were generally found below the health limit guideline, except in high industrial areas. In addition, pathogenic or indicator microorganisms that include, but are not limited to, Escherichia coli, total and faecal coliforms, Campylobacter, Salmonella, Legionella, Pseudomonas, Cryptosporidium, Enterococci, Giardia, Aeromonas, and Mycobacterium avium Complex (MAC) have been detected in rainwater collected in Australia. However, epidemiological evidence suggests that drinking rainwater does not increase the risk of gastrointestinal disease. It was also identified that there is a need for further research investigating the potential for rainwater to be a source of infection for opportunistic pathogens. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been rapid installation of domestic rainwater tanks in many Australian cities in response to drought, and facilitated by subsidies and development regulations. Tanks have been portrayed as a challenge to the dominance of 'big water' and a means of elevating routine interactions with water to a practical consciousness that can stimulate lasting changes in the way that water is consumed. Telephone surveys and focus groups were used to identify the ways that households that have acquired tanks, either by choice or through development conditions, interact with their tank water. Meaning was attributed to tank water in at least three distinct ways that highlight the lack of maturity of domestic rainwater tanks as an acceptable technology. Some saw the water as a personal supply to safeguard their lifestyle against restrictions. Others understood their tanks as a personal contribution to the communal environment by reducing dependence on mains water supply. The third group regarded the tank as an extension of the water supply infrastructure. The existence of mandatory connections from tanks to internal infrastructure, such as toilet and laundry facilities, correlated strongly with the likelihood that tank water was not seen as a personal resource. Tanks perpetuate the distinction between basic water supplies and luxury water that was established during water restrictions under drought conditions. [ABSTRACT FROM AUTHOR]

Biomonitoring has been used internationally from as early as the 1970s to monitor environmental change associated with the transport of metals within airborne particulate matter. The low cost methods have allowed early detection of environmental change enabling regulatory adjustment of emissions limits and supporting emissions reductions, and the ability to monitor over large distances. However, without standardised methodology in Australia, the approach has largely been over-looked nationally as a screening tool for environment change. Media releases in Australia highlight the national significance of long-range metal migration in air. The health relevance includes South Australian regulators imposing bans on eating locally caught seafood and guidance against using rainwater tanks in Port Pirie due to contamination by atmospheric lead. The environmental relevance includes atmospheric metals from historic mining having contaminated the Tasmanian Wilderness World Heritage Area and significantly altering the natural geochemical signal of lakes. The cultural relevance includes the 2009 dust storm which made international news that ‘radioactive laced’ dust from inland mines was being deposited on Sydney. This poster reviews current international approaches to the use of lichen and moss for biomonitoring and considers limitations and benefits of the implementation of techniques in Australia. [ABSTRACT FROM AUTHOR]

In Australia, when stormwater systems were first introduced over 100 years ago, they were constructed independently of the sewer systems, and they are normally the responsibility of the third level of government, i.e., local government or city councils. Because of the increasing age of these stormwater systems and their worsening performance, there are serious concerns in a significant number of city councils regarding their deterioration. A study has been conducted on the structural deterioration of concrete pipes that make up the bulk of the stormwater pipe systems in these councils. In an attempt to look for a reliable deterioration model, a probabilistic neural network (PNN) model was developed using the data set supplied from participating councils. The PNN model was validated with snapshot-based sample data, which makes up the data set. The predictive performance of the PNN model was compared with a traditional parametric model using discriminant analysis on the same data set. Structural deterioration was hypothesised to be influenced by a set of explanatory factors, including pipe design and construction factors—such as pipe size, buried depth—and site factors—such as soil type, moisture index, tree root intrusion, etc. The results show that the PNN model has a better predictive power and uses significantly more input variables (i.e., explanatory factors) than the discriminant model. More importantly, the key factors for prediction in the PNN model are difficult to interpret, suggesting that besides prediction accuracy, model interpretation is an important issue for further investigation. [ABSTRACT FROM AUTHOR]