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The supply of safe drinking water to rural communities has always been challenging, unlike in most large cities where government authorities have constructed central water supply systems. In many rural areas, primary water sources such as surface water and groundwater are at risk of contamination with rapid agricultural and industrial growth and climate change-related issues. Rainwater harvesting is an ancient practice for rural communities, and the momentum around its use is continually growing in recent years. However, the lack of sustainable treatment facilities on a small scale encourages dwellers to consume harvested rainwater (HRW) without any treatment even though drinking untreated HRW may have multiple health impacts in many cases. There are several methods of treating HRW. While chlorination is extensively used to disinfect water in large volumes, e.g., central drinking water supply systems), it has not been widely adopted for treating water on a small scale. We present a scoping review to explore whether chlorination could be a viable option for disinfecting HRW at a domestic level. It is found that inadequate treatment prior to chlorine disinfection could produce chlorine disinfection byproducts (DBPs). Limited data on DBP concentrations in HRW are available to assess its health implications. Based on this review, it is argued that chlorination could be an option for treating HRW at a domestic level when limitations associated with this method (such as safe storage, appropriate sustainable technology, and lessening DBPs by lowering total organic carbon before chlorination through other treatment methods) are resolved. [ABSTRACT FROM AUTHOR]

This study uses a multi-criteria decision analysis approach based on geographic information system (GIS) to identify suitable sites for rainwater harvesting (RWH) structures (such as farm dam, check dam and contour bund) to meet irrigation demand in Greater Western Sydney region, New South Wales, Australia. Data on satellite image, soil, climate, and digital elevation model (DEM) were stored in GIS layers and merged to create a ranking system, which were then used to identify suitable RWH (rainwater harvesting) areas. The resulting thematic layers (such as rainfall, land use/land cover, soil type, slope, runoff depth, drainage density, stream order and distance from road) were combined into one overlay to produce map of RWH suitability. The results showed that 9% of the study region is 'very highly suitable' and 25% is 'highly suitable'. On the other hand, 36% of the area, distributed in the north-west, west and south-west of the study region, is 'moderately suitable'. While 21% of the region, distributed in east and south-east part of the region, has 'low suitability' and 9% is found as 'unsuitable area'. The findings of this research will contribute towards wider adoption of RWH in Greater Western Sydney region to meet irrigation demand. The developed methodology can be adapted to any other region/country. [ABSTRACT FROM AUTHOR]

This study presents a review of recent rainwater harvesting (RWH) research by a bibliometric analysis (based on performance analysis and science mapping method). Following the inclusion/exclusion criteria, a total of 3226 publications were selected for this bibliometric analysis. From the selected publications, the top journals were identified according to number of publications and number of citations, as well as the authors with the highest number of publications. It has been found that publication rate on RWH has been increasing steadily since 2005. Water (MDPI) journal has published the highest number of publications (128). Based on the literature considered in this review, the top five authors are found as Ghisi, E., Han, M., Rahman, A., Butler, D. and Imteaz, M.A. in that order. With respect to research collaborations, the top performing countries are USA–China, USA–Australia, USA–UK, Australia–UK and Australia–China. Although, the most dominant keywords are found to be 'rain', 'rainwater', 'water supply' and 'rainwater harvesting', since 2016, a higher emphasis has been attributed to 'floods', 'efficiency', 'climate change', 'performance assessment' and 'housing'. It is expected that RWH research will continue to rise in future following the current trends as it is regarded as a sustainable means of water cycle management. [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]

This paper presents a review of water research, development, and management in Bangladesh, with examples drawn from the past and present. A bibliometric analysis is adopted here to analyze the water-related publication data of Bangladesh. Water-quality-related research is the dominating research field in Bangladesh as compared to water-quantity (floods and droughts)-related ones. The most productive author was found to be Ahmed KM for water-related publication in Bangladesh. The arsenic contamination in Bangladesh has received the highest attention (13 out of the top 15 highly cited papers are related to arsenic contamination). Climate-change-related topics have been showing an increasing trend in research publications over the last 5 years. Bangladesh Delta Plan 2100, prepared recently, is a visionary master plan that is expected to shape water management in Bangladesh in the coming decades to adapt to climate change. A set of recommendations is made here to achieve sustainable water management in Bangladesh. [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]

Groundwater resources are often the main source of drinking water for remote communities, but they are increasingly found to be unsuitable, and a source of ill health in many parts of the world. High annual rainfall in monsoonal regions makes rainwater harvesting an attractive alternative, but lack of infrastructure for capturing and storing sufficient quantities is often restrictive. This study focuses on the coastal region of Bangladesh where groundwater supplying tubewells are progressively found to contain arsenic and high salinity, and where cyclones are a common cause of damage to infrastructure. The aim of this study is to evaluate the potential of a village scale rainwater harvesting scheme as a solution to water security concerns. Analysis of various size rainwater storage systems (RSS) is conducted using daily rainfall data from Khulna Station in Bangladesh. It was found that a village scale RSS with 3 m deep and 100 m by 100 m surface area could supply 100 L/p/d for 85% of the year. The reliability could feasibly be increased to 100% with seasonal water restrictions. The village scale RSS is compared with an individual household level RSS. Advantages of the village scale RSS include the opportunity for improved management and water quality monitoring, and the potential for public-private partnerships. The proposed methodology can be adapted to other monsoonal delta regions to enhance water supply. [ABSTRACT FROM AUTHOR]

Abstract This review investigates the potential of using roof harvested rainwater to support urban agriculture. Among the important issues, we concentrate on system configuration, modelling and economic analysis while comparing research from both developed and developing countries. Urban agriculture contributes notably to food and nutrition in many developing nations, and is receiving increasing attention in developed countries due to a cultural shift towards sustainable living coupled with increasing demand and food prices. Domestic rainwater harvesting (RWH) from rooftops increasingly forms part of integrated water management strategies and has seen a considerable amount of research on modelling and economics, as has water use in agriculture. However domestic RWH usually focuses on in-house usage such as toilet flushing and washing, while there has been very little research specific to its use in food production. In developing countries home gardens often fail due to insufficient rainfall and water supply. In general, promoting urban agriculture and the greening of cities begs the question of whether there is sufficient water available to support it and where additional water will come from. A scoping review following a five step criteria is adopted here to understand the extent to which roof harvested rainwater can be used to support urban agriculture and what are the associated economic implications. In view of the broad scope of the water-food-energy-ecosystem nexus, under which this research fits, this scoping review is deemed better suited (in absence of an ample body of literature) to the synthesis of relevant researches than a systematic review. The major contributions of this review are to highlight the lack of initiatives to utilise harvested rainwater in urban agriculture, to explore the obstacles and to lay a foundation for new areas of research within the sustainable urban development paradigm. Furthermore, the comparison between developed and developing countries helps bring to light cultural, socio-economic and political obstacles to improving sustainability and healthier living in the urban environment. The impact of history and traditions on crop choice, growing methods and consequently water consumption rates are also discussed. This review is particularly relevant to three of the United Nations' Sustainable Development Goals (i.e. Cleaner and Sustainable Cities; Health and Wellbeing and No Hunger). It is found that there is a considerable potential to supply water to urban agriculture using customised roof RWH system designs. For example, one study reports that up to 41% of urban horticulture sites in Rome could be sustained by water harvested from local roofs. Irrigating a small garden (20 m2) with harvested rainwater can increase the yield by about 20% meeting the caloric requirements of a typical Indian household. Further research is needed on the integration of roof rainwater harvesting and urban agriculture to maximise its contribution to food production and sustainability. Highlights • There is little research on roof harvested rainwater use in urban agriculture. • Modelling and economic analysis of RWH and urban agriculture systems reviewed. • The integration of RWH with urban agriculture is an important future research area. [ABSTRACT FROM AUTHOR]

Rainwater is a naturally occurring potentially clean source of water. There has been an increased interest in rainwater harvesting (RWH) in both developing and developed nations. RWH can alleviate the effects of accelerated urbanisation and improve their water security in the face of uncertain future climate patterns. Australia's management of her millennium drought has proved the effectiveness of RWH systems. Success in Australia is promising for developing countries with inadequate water supply for drinking and sanitation and unreliable centralised water supply systems. However, there is little research on the economic analysis of RWH systems in developing countries. Here we have developed an economic analysis tool, called ERain, to combine daily performance analysis of RWH systems with life cycle cost analysis for use in economic evaluation. ERain has shown that the recent tendency towards smaller tanks in Australia is a poor choice economically, that RWH systems in Kenya can be economically beneficial if installed without reticulation, and that reliability (the percentage of days that the demand is met) can be a financial issue. ERain provides a realistic framework for establishing sustainable RWH solutions. The relationship between the benefit-cost ratio, reliability and efficiency (the percentage of available water used) is discussed as well as discrepancies between the benefit-cost ratio (BCR), and net present value (NPV) as economic indicators. Results highlight the need for innovation and reduction in capital and on-going costs associated with RWH systems in preference to increasing the price of water to increase their economic viability. The impact of paying elevated prices for water purchased from street vendors on the other hand demonstrates the dependency of RWH system economic viability on regional freshwater cost. Results also show that a rebate that matches tank size would be a good initiative to encourage the installation of larger tanks and increase water security, while relying on customer perspective of value will tend towards installation of smaller tanks and a superficial water security. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) is perhaps the most ancient practice to meet water supply needs. It has received renewed attention since the 1970s as a productive water source, water savings and conservation means, and sustainable development tool. In RWH, it is important to know how much water can be harvested at a given location from a given catchment size, whether the harvested water meets the intended water quality, whether the RWH system is economically viable and whether the state regulations favor the RWH. Furthermore, the selected RWH system should be suitable to local rainfall and field conditions, downstream impacts, and socio-economic and cultural characteristics. In this regard, this paper provides an overview of the special issue on "Rainwater Harvesting: Quantity, Quality, Economics and State Regulations". The selected papers cover a wide range of issues that are relevant to RWH such as regionalization of design curves, use of spatial technology, urban agriculture, arid-region water supply, multi criteria analysis and application of artificial neural networks. [ABSTRACT FROM AUTHOR]

Water management is an important issue in urban design due to the growing concern of water scarcity. As a result, rainwater harvesting system has received notable attention as an alternative water source. Rainwater is one of purest form of waters and can easily be accessed via a rainwater harvesting system. In general, performance of a rainwater harvesting system is estimated based on historical rainfall data without the possible impacts of climate change on rainfall. However, rainfall pattern is likely to change in the future as a consequence of climate change that may affect the performance of a rainwater harvesting system. But research on climate change impacts on rainwater harvesting is limited. The objective of this study is to understand the plausible impacts of climate change on the performances (i.e. water savings, reliability and water security) of a residential rainwater harvesting system, based on the projected future rainfall conditions. A continuous daily simulation water balance model is developed based on behavioural analysis and yield-after-spillage criteria to simulate the performances of a rainwater harvesting system. The analysis is conducted at five locations in the Greater Sydney region, Australia. The results indicate that performances of a rainwater harvesting system will be impacted negatively due to climate change conditions in the future. It is found that a given tank size at the selected locations would not be able to supply expected volume of water under changing climate conditions in future. Water savings is going to be reduced from a rainwater harvesting system in future (e.g. 2%–14% reduction for 3 kL tank for indoor water demand). Moreover, number of days in a year to meet the water demand by a rainwater harvesting system (i.e. reliability) is likely to be reduced (e.g. 3%–16% reduction for 3 kL tank for indoor water demand). Also, the percentage of days a rainwater tank would remain completely empty is likely to increase in future (e.g. 12% in future climate conditions in comparison to 8% in historical conditions for indoor water demand). Furthermore, it is found that the performance of a rainwater harvesting system will be more affected in dry season than the wet season. The findings of the study will help water authorities and policy makers, as well the home owners to improve their understanding of climate change impact on residential rainwater harvesting system, and will assist them in selecting appropriate rainwater tank size in the context of climate change. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) plays an important role in increasing water security for individuals and governments. The demand for tools to enable technical and economic analysis of RWH systems has led to a substantial body of research in the recent past. This paper focuses on the economic aspects of domestic RWH in urban and peri-urban environments. In this regard, key issues are identified and discussed including quality and quantity of harvested water, the water demand profile, the scale of installation, interest rates, the period of analysis, real estate value, and the water-energy-food nexus. Kenya and Australia are used as reference points having different economies and opposing RWH policies. It has been found that the previous studies on financial aspects of RWH systems often had conflicting results. Most of the economic analyses have ignored the full benefits that a RWH system can offer. In view of the varying and conflicting results, there is a need to standardize the methods of economic analysis of RWH systems. [ABSTRACT FROM AUTHOR]

Water is a scarce resource in arid regions, and hence water harvesting is critically important in these regions for which many different means are adopted including groundwater and rainwater harvesting. This paper examines the feasibility of rainwater harvesting from roof catchments in arid regions of Australia. For this, ten representative locations in the arid regions of Australia are selected. Also, ten different sizes of rainwater tanks ranging from 5 kL to 50 kL and three different combinations of water uses are considered. A model is developed to simulate the performance of a rainwater harvesting (RWH) system. It is found that the reliability of a RWH system is highly dependent on mean annual rainfall at the location of interest. It is found that a 20 kL tank can provide a reliability of 61%–97% for toilet and laundry use depending on the location within the Australian arid regions. At the current water price, RWH system is not financially viable in the Australian arid regions. The methodology adopted in this paper can be adapted to other similar arid regions of the world. [ABSTRACT FROM AUTHOR]

Abstract: Due to greater environmental awareness and mandatory water restrictions in many Australian cities, rainwater tanks have become popular in recent years. This paper investigates the water savings potential of rainwater tanks fitted in detached houses at 10 different locations in Greater Sydney, Australia. A water balance simulation model on daily time scale is developed and water savings, reliability and financial viability are examined for three different tank sizes, 2kL, 3kL and 5kL. It is found that the average annual water savings from rainwater tanks are strongly correlated with average annual rainfall. It is also found that the benefit cost ratios for the rainwater tanks are smaller than 1.00 without government rebate. It is noted that a 5kL tank is preferable to 2kL and 3kL tanks and rainwater tanks should be connected to toilet, laundry and outdoor irrigation to achieve the best financial outcome for the home owners. The results from this study suggest that government authorities in Sydney should maintain or possibly increase the rebate for rainwater tanks to enhance its acceptance. [Copyright &y& Elsevier]

Abstract: With the aim of developing a comprehensive decision support tool for the performance analysis and design of rainwater tanks, a simple spreadsheet based daily water balance model was developed using daily rainfall data, contributing roof area, rainfall loss factor, available storage volume, tank overflow and rainwater demand. In order to assess reliability of domestic rainwater tanks in augmenting partial household water demand in Melbourne (Australia) area, the developed water balance model was used for three different climatic conditions (i.e. dry, average, and wet years). Historical daily rainfall data was collected from a rainfall station near Melbourne city central. From historical rainfall data three representative years (driest, average and wettest) were selected for the current analysis. Reliability is defined as percentage of days in a year when rainwater tank was able to supply the intended partial demand for a particular condition. For the three climatic conditions, several reliability charts are presented for domestic rainwater tanks in relations to tank volume, roof area, number of people in a house (i.e. water demand) and percentage of total water demand to be satisfied by harvested rainwater. In brief, for a two-people household scenario, ∼100% reliability can be achieved with a roof size of 150–300m2 having a tank size of 5000–10,000L. However, for a four-people household scenario, it is not possible to achieve a 100% reliability, even with a roof size of 300m2 and a tank size of 10,000L. [Copyright &y& Elsevier]

Abstract: Rainwater tanks for larger roof areas need optimisation of tank size, which is often not carried out before installation of these tanks. This paper presents a case study of rainwater tank evaluation and design for large roof areas, located in Melbourne, Australia, based on observed daily rainfall data representing three different climatic regimes (i.e. dry average, and wet years). With the aim of developing a comprehensive Decision Support Tool for the performance analysis and design of rainwater tanks, a simple spreadsheet based daily water balance model is developed using daily rainfall data, contributing roof area, rainfall loss factor, available storage volume, tank overflow and irrigation water demand. In this case study, two (185m3 and 110m3) underground rainwater tanks are considered. Using the developed model, effectiveness of each tank under different climatic scenarios are assessed. The analysis shows that both the tanks are quite effective in wet and average years, however less effective in dry years. A payback period analysis of the tanks is preformed which reveals that the total construction cost of the tanks can be recovered within 15–21 years time depending on tank size, climatic conditions and future water price increase rates. For the tanks, a relationship between water price increase rates and payback periods is developed. The study highlights the need for detailed optimisation and financial analysis for large rainwater tanks to maximise the benefits. [Copyright &y& Elsevier]

Abstract: Rainwater tanks have become popular in large Australian cities due to water shortage and greater public awareness towards sustainable urban development. Rainwater harvesting in multi-unit buildings in Australia is less common. This paper investigates the water savings potential of rainwater tanks fitted in multi-unit residential buildings in three cities of Australia: Sydney, Newcastle and Wollongong. It is found that for multi-unit buildings, a larger tank size is more appropriate to maximise water savings. It is also found that rainwater tank of appropriate size in a multi-unit building can provide significant mains water savings even in dry years. A prediction equation is developed which can be used to estimate average annual water savings from having a rainwater tank in a multi-unit building in these three Australian cities. [ABSTRACT FROM AUTHOR]

Some of these are (i) drinking water provision from RWH systems in rural areas fitted with automatic disinfection systems; (ii) RWH at the community scale; (iii) RWH for livelihood improvement; (iv) RWH for mitigating heat island effects based on evaporative cooling; (v) the drinking water production industry based on harvested rainwater in rural areas; (vi) RWH for groundwater recharge; (vii) storing harvested rainwater in seawater bodies and in large flexible rubber balloons/bladder tanks; (viii) the impact of climate change on RWH; (ix) innovative rainwater tanks in line with site and water quality requirements; (x) RWH in the water-food-energy-ecosystems nexus; and (xi) artificial-intelligence-based automatic/digital RWH systems with water quantity and quality monitoring. Rainwater harvesting (RWH) can assist in managing water cycle in both urban and rural areas by offering a range of sustainable solutions. By applying ten different tank sizes and three different water uses, they showed that an RWH system can meet the toilet and laundry water demand very effectively (reliability in the range of 80-100%) in all the Australian capital cities; however, an RWH system is not highly reliable for irrigation use as irrigation water demand is too high. RWH systems can contribute notably towards achievements of water-related sustainable development goals (SDGs), and hence RWH is being promoted in many countries. [Extracted from the article]

The production and distribution of a sufficient quantity of food and water of satisfactory quality is at the heart of sustainable development. At the small domestic scale, roof-harvested rainwater can make a significant contribution to food supply and distribution systems (production, handling, storage, and transportation). In this paper, we compare the potential crop production of a small garden plot using three methods of watering: (1) rainfed only with no irrigation; (2) irrigated with the ideal amount of water; and (3) rainwater tanks of various sizes installed and used to irrigate the plot. Yield was determined on the basis of the yield calculation method presented in FAO 33. It was found that yields can be increased considerably by installing a correctly managed rainwater storage system (RSS). A 3 kL RSS connected to a 120 m2 roof can increase yields in Nairobi from 40 kg to 96 kg. In Sydney, a larger roof of 200 m2 can increase yields from 66 kg to 143 kg. This study makes an important contribution to water and food security-related sustainable development goals. [ABSTRACT FROM AUTHOR]

This paper presents reliability, water demand and economic analysis of rainwater harvesting (RWH) systems for eight Australian capital cities (Adelaide, Brisbane, Canberra, Darwin, Hobart, Melbourne, Perth and Sydney). A Python-based tool is developed based on a daily water balance modelling approach, which uses input data such as daily rainfall, roof area, overflow losses, daily water demand and first flush. Ten different tank volumes are considered (1, 3, 5, 10, 15, 20, 30, 50, 75 and 100 m3). It is found that for a large roof area and tank size, the reliability of RWH systems for toilet and laundry use is high, in the range of 80–100%. However, the reliability for irrigation use is highly variable across all the locations. For combined use, Adelaide shows the smallest reliability (38–49%), while Hobart demonstrates the highest reliability (61–77%). Furthermore, economic analysis demonstrates that in a few cases, benefit–cost ratio values greater than one can be achieved for the RWH systems. The findings of this study will help the Australian Federal Government to enhance RWH policy, programs and subsidy levels considering climate-sensitive inputs in the respective cities. [ABSTRACT FROM AUTHOR]

In this study, we have examined the viability of rainwater harvesting system in whole Australia in terms of water savings, reliability and financial viability. Three different cases of water use have been considered: (i) toilet flushing and laundry; (ii) irrigation; and (iii) combination of toilet flushing, laundry and irrigation (combined). The analysis is performed using data from 601 Australian rainfall stations. The results show that the reliability of a rainwater harvesting system is considerably high (80–100%) for 'toilet flushing and laundry' use. For 'combined' use, the reliability drops below 50% for most of the continent. We have presented the detail results of spatial distribution of reliability and water savings for a tank size of 7.5 kL. It is found that the benefit cost ratio for rainwater harvesting system over one can be achieved under certain conditions. The findings of this study will be useful in sustainable water resource management in Australia using rainwater harvesting system. Image, graphical abstract Mean annual water saving for a 7.5 kL rainwater tank: (a) toilet flushing and laundry (b) irrigation (c) combined [ABSTRACT FROM AUTHOR]

Rainwater harvesting is a well-known method of collecting and storing rainwater that can subsequently be used for different purposes. Most of the recent studies focused on how to use the harvested rainwater effectively to reduce the use of potable water for non-potable usage and ultimately cut down the water demand from the mains. However, studies on rainwater harvesting system have rarely been undertaken for drinking water production at the household level in rural areas, where a centralised water supply system is unavailable. The present study reports the feasibility of a small-scale rainwater harvesting system intended to produce drinking water for rural/isolated communities. A number of parameters such as roof size, tank size, water demand and daily filtration rate were taken into consideration to examine the performance of the rainwater harvesting system. Local meteorological and costing data were used in the study assuming that the system would provide drinking water to a typical household of four people. It is found that the small-scale rainwater harvesting system can satisfy the drinking water demand throughout the year with 90–97% reliability depending on the roof size. In addition, the capacity of monthly water production from different rainwater harvesting systems is presented that can be adopted to increase the reliability further. A life cycle cost analysis of the system is presented including sensitivity analysis. It is found that the preferred rainwater tank size for a household having 100 m2 roof area in Werrington, New South Wales is 5 kL. The system payback time falls between 1 and 6 years depending on the price of the produced drinking water. The cost of the produced drinking water including disinfection and mineral addition is found to be 1.04 AU₵/L. In addition, the intended rainwater harvesting system could result in a monetary return of AU$ 35,494 over its lifetime of 25 years. This study shows that the production of drinking water by rainwater harvesting for rural communities is possible at an affordable cost, which is aligned to the United Nation's Sustainable Development Goal 6: Clean Water and Sanitation. Image 1 • A small scale RWH system can provide drinking water to rural households. • A 5 kL rainwater tank is the optimum size for 100 m2 roof area in Werrington, NSW. • System payback period falls between 1 and 6 years depending on water price. • The proposed RWH system results in a return of AU$ 35,494 over its lifetime. [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]

The aim of the study was to devise a sustainable solution for drinking water supply in rural communities at an affordable cost, which is specifically related to the two of the United Nation's Sustainable Development Goals: G3. Good health and well-being and G6. Clean water and sanitation. In this regard, the objective of this scoping review is to evaluate the sustainability, in relation to technical, financial and acceptability aspects, of a small-scale rainwater harvesting system to identify whether it can fulfil the demand of drinking water at a household level in rural communities at an affordable cost and in a sustainable manner. We have reviewed recent studies on rainwater harvesting systems to investigate: i. Whether a small scale system is economically and technically viable at rural community level, ii. Whether the quality of harvested rainwater meets drinking water standard, iii. Why rainwater harvesting system has not become mainstream water supply system as yet and iv. how climate change can affect the reliability of a small scale rainwater harvesting system? It is found that small scale roof connected rainwater harvesting system is likely to be economically and technically feasible when certain steps and risk assessment procedures are followed in designing and maintaining the system. It is also found that harvested rainwater needs robust treatment before human consumption. The public perceptions, capital cost, lack of knowledge on rainwater harvesting system, mix information about the quality of rainwater, risk associated with the system because of climate change, degradation of stored water quality with time and in some cases inadequate policies obstruct widespread adoption of rainwater harvesting technology. The world may see a dramatic change is socio-economic development of many rural areas when a sustainable drinking water supply system is established via a rainwater harvesting system. • There has been limited research on rainwater harvesting for producing drinking water. • Harvested rainwater in rural areas are generally consumed without formal treatment. • Inappropriate design of rainwater systems is a barrier to achieve sustainability. • Impact of climate change on RWH system reliability should be considered in WBM. • Proper treatment and disinfection method can convert rainwater to drinking water. [ABSTRACT FROM AUTHOR]

While the practice of rainwater harvesting (RWH) can be traced back millennia, the degree of its modern implementation varies greatly across the world, often with systems that do not maximize potential benefits. With a global focus, the pertinent practical, theoretical and social aspects of RWH are reviewed in order to ascertain the state of the art. Avenues for future research are also identified. A major finding is that the degree of RWH systems implementation and the technology selection are strongly influenced by economic constraints and local regulations. Moreover, despite design protocols having been set up in many countries, recommendations are still often organized only with the objective of conserving water without considering other potential benefits associated with the multiple-purpose nature of RWH. It is suggested that future work on RWH addresses three priority challenges. Firstly, more empirical data on system operation is needed to allow improved modelling by taking into account multiple objectives of RWH systems. Secondly, maintenance aspects and how they may impact the quality of collected rainwater should be explored in the future as a way to increase confidence on rainwater use. Finally, research should be devoted to the understanding of how institutional and socio-political support can be best targeted to improve system efficacy and community acceptance. [ABSTRACT FROM AUTHOR]