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Environmental performance of hybrid rainwater-greywater systems in residential buildings
Abstract
The objective of this paper is to present and to apply a method based on Life Cycle Analysis (LCA) which was used to assess the environmental performance of hybrid rainwater-greywater systems in residential buildings. The method was applied in a case study in single-family residences in southern Brazil. The environmental impacts of two scenarios were compared: a house with a decentralized hybrid rainwater-greywater system and the same house with a conventional centralized water system. SimaPro software was used for environmental impact analysis and ReCiPe was used as an assessment tool. The average potential for potable water savings through the implementation of the hybrid rainwater-greywater system was 41.9%, the potential for domestic sewage reduction was 40% and the total energy consumption reduction in comparison to the conventional system scenario was 36.1%. The most significant environmental impacts in the assessment of the life cycle were related to the operational phase. The energy savings in the operation phase is essential to minimize the impacts observed and to maximize the sustainability and potential benefits. The findings of this study indicate that the scenario with hybrid rainwater-greywater system represents the most environmentally favourable option in single-family residences. The method is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new hybrid rainwater-greywater systems. It may also contribute to the recommendation of potential environmental mitigation measures and to the development of specific public policies to encourage the residential use of alternative water sources.
... These systems combine both alternative water sources in the same building, which leads to a reduction in water demand by replacing potable water for enduses that do not require high water quality standards (Leong et al., 2018). According to Marinoski and Ghisi (2019), in contrast to RWHS alone, HS can achieve higher potable water savings and more constant water flows during dry periods due to the input of GW. Furthermore, these systems integrate the benefits of both RWHS and GWRS, reducing the demand of water from centralized water treatment plants, wastewater to be treated in centralized wastewater treatment plants, and stormwater flows, thus minimize flooding risks, and environmental impacts to receiving water bodies. ...
... Studies have been carried out that address the use of RWHS and GWRS at a city scale (Khalkhali et al., 2021;Tarpani et al., 2021), but considering each one as an independent alternative and not their joint use as an alternative that integrates the two options. Marinoski and Ghisi (2019) carried out a LCA to establish the environmental performance of a HS in single-family households in the south of Brazil in comparison with the local CS. Leong et al. (2019) analyzed the environmental and economic impacts of a CS compared to RWHS, GWRS, and HS in a commercial building and a residential building in a tropical climate context using LCA and Life Cycle Costing (LCC); Kobayashi et al. (2020) assessed the environmental impacts of decentralized greywater treatment (Constructed Wetlands and Membrane Bioreactors) with various reuse options applicable to urban areas in Canadá. ...
... The household interviews developed as part of the technical study in Oviedo-Ocaña et al. (2018) provided data on users' practices, preferences and water demand, critical to stablish the potential potable water savings. Marinoski and Ghisi (2019) recommends to carry out this type of interviews and as a further improvement, in situ monitoring of water demand and discharges by using sensors. This will allow a better tank sizing leading to more accurate designs (Coombes and Barry, 2007). ...
Rainwater harvesting systems (RWHS) and greywater reuse systems (GWRS) are prominent alternatives for urban water management, which contribute to improving water use efficiency and conservation. The evaluation of these systems has been based mainly on technical, social and financial aspects. Recently, some studies have analyzed the environmental performance of RWHS and GWRS separately, showing promising results associated with lower impacts in comparison to conventional centralized water distribution systems. However, from an environmental perspective, limited research has been done to evaluate hybrid systems that integrate RWHS and GWRS. This study aims to analyse and compare the environmental performance of a hybrid system with a centralized system in a high water consumption household located in Bucaramanga Metropolitan Area, Colombia. The Life Cycle Assessment methodology, using the GaBi software, was applied to quantify the environmental impacts of the two water system options. The implementation of the hybrid system saves about 131 m³/year of potable water, 42.5% of total potable water consumption and reduces flows to the wastewater treatment plant by 20%. The hybrid system has better environmental performance compared to the centralized system, with lower impacts observed for 12 out of the 13 midpoint impact categories considered and all 3 endpoint impact categories in the ReCiPe impact assessment method used. The operational phase causes greater environmental impacts compared to the construction phase and the processes involved in the treatment of potable water and wastewater significantly affect the environmental impacts in both water system options compared to other life cycle phases. Overall, our study confirms the environmental benefits of the hybrid system and provides evidence useful for decision-makers regarding alternative water systems. However, further study is needed to refine the input data used for some of the processes to reflect the specific context in Colombia.
... In the building sector, this concern may lead to the choice of strategies for saving water, such as the adoption of water-saving technologies, as well as the use of alternative sources of water supply [14][15][16]. Among the alternative sources of water supply, several studies evaluate the use of rainwater harvesting systems [13,[17][18][19] and water reuse systems [20,21]. ...
... There was a 7% increase in the effluent volume from rainfall as calculated by Vieira and Ghisi [28]. The greywater reuse system was composed of: upper and lower tanks, a wetland treatment system; a disinfection system (chlorinator), a motor pump, horizontal and vertical piping, hydraulic fittings, retention valve, and a float level valve [14,21] (Figure 2). The measurement period for the single flush valve device was from 27 March 2017 to 17 July 2017 and the measurement period for the dual-flush valve device was from 8 August 2017 to 22 October 2017. ...
... The use of the subsurface wetland vertical flow system for wastewater treatment was chosen based on its high treatment efficiency [25], as it does not require very specialized operational skills for its maintenance and displays low energy consumption [26]. The subsurface wetland vertical flow system used with a chlorine dosing pump was adopted by Marinoski et al. [14] and Marinoski and Ghisi [21]. ...
The use of plumbing fixtures to promote water saving in the built environment is a common practice in water conservation programs. However, the environmental implications of fixtures replacement should be taken into consideration. This paper analyzes three different scenarios for the provision of water in toilets installed in a university campus. In scenarios 1 and 2, single flush and dual flush devices were installed in the toilets, respectively. In scenario 3, in addition to the installation of dual flush devices, a greywater reuse system from the lavatories was analyzed. The objective is to evaluate, through the Life Cycle Assessment, the environmental aspects related to these scenarios. The economic analysis of the three scenarios was also carried out. Measurements were taken on all plumbing fixtures installed in a building of a university campus in Southern Brazil. The research was conducted using smart meters in two periods: with single flush and dual flush devices installed in toilets. Considering the environmental impacts analyzed, scenario 3 presented lower water and energy consumption in the life cycle. Scenario 2, however, presented lower global warming potential. The net present value results were R$ 23,575.71, R$ 19,091.41, and R$ 22,500.55 for scenarios 1, 2 and 3, respectively.
... Tal condição impõe a necessidade de uma estação de tratamento de água cinza (ETAC) visando adequá-la aos padrões estéticos e microbiológicos preconizados. Entretanto, estudos epidemiológicos e com o uso de análise quantitativa de risco microbiológico para avaliação do reúso de AC em irrigação e descarga de bacia sanitária demonstram que o risco é desprezível (Busgang et al., 2015;Benami et al., 2016;Shi et al., 2018) O reúso de AC promove tanto a redução da demanda do sistema de abastecimento de água, quanto a diminuição do volume de efluente coletado e tratado pelo sistema de esgoto público, minimizando o consumo de energia associado não apenas ao sistema de abastecimento de água, mas também à coleta, transporte e tratamento de esgoto (Marinoski e Ghisi, 2019). ...
... Este foi um aspecto considerado durante o dimensionamento, evitando sistemas superdimensionados. A participação da etapa de implantação correspondeu à maior parte do impacto ambiental, chegando a 56.4% da energia primária incorporada e 63.7% das emissões de CO 2 eq, ao contrário do que foi encontrado por outros autores (Marinoski et al., 2019;Silva, 2018). Ainda nesta fase, os materiais com plástico em sua composição (reservatório e os tubos de PVC), representaram 80.6% do impacto energético e 60.3% do CO 2 eq, demostrando a necessidade de otimização no uso destes materiais. ...
... Two alternatives for decreasing potable water consumption are using rainwater and greywater. These have been studied for use in different types of buildings and regions: a multi-family residential building in Sweden (Villarreal and Dixon 2005), highrise buildings in Australia (Zhang et al. 2009); single-family houses in Brazil (Marinoski, Rupp, and Ghisi 2018;Marinoski and Ghisi 2019); and commercial and residential buildings in Malaysia (Leong et al. 2018) to quote just a few. ...
... which represents 42.2% of the daily water consumption. This figure is close to the non-potable water consumption reported by Marinoski and Ghisi (2019) in low-income houses in Florianópolis, Brazil (42.9%); by DeOreo et al. (2016) in houses in the USA and Canada (41.0%); and by Hammes, Ghisi, and Thives (2020) in a house in Blumenau, Brazil (46.4%). ...
This paper presents a case study on the economic feasibility analysis of rainwater harvesting in single-family houses located in Imbituba, Brazil. A base case scenario was chosen and 108 scenarios were evaluated considering different roof areas, number of residents, potable water and rainwater demands. All scenarios were assessed by means of computer simulations. The payback period for the base case was 14.8 years, and the internal rate of return was 9.1% per year. As for the scenarios analysed, rainwater harvesting was economically feasible in 57.4% of the cases; payback periods ranged from 9.3 to 19.7 years, and internal rates of return reached 15.3% per year. The scenarios with the best economic feasibility were those with the largest number of residents, roof areas and daily water demand. The main conclusion is that rainwater harvesting in Imbituba and cities with similar characteristics can be economically feasible.
... Similarly, a number of case studies have looked at hybrid systems, combining facets of RWH with graywater recycling ( Faragò et al., 2019 ;Hasik et al., 2017 ;Jeong et al., 2018 ;Leong et al., 2019 ;Marinoski & Ghisi, 2019 ;Stephan & Stephan, 2017 ;Zanni et al., 2019 ). Though graywater was found to be a more reliable water source, system size, electricity consumption and electricity grid emissions were found to heavily influence environmental and cost performance of each system. ...
... Ghimire et al. (2019) found that a combined RWH/ACH system had lower impacts than individual systems and yielded a greater and more constant water supply. Similarly, several researchers evaluated systems that combined graywater recycle with RWH ( Hasik et al., 2017 ;Leong et al., 2019 ;Marinoski & Ghisi, 2019 ;Stephan & Stephan, 2017 ). Future research should explore these potential synergies using a similarly comprehensive framework as the one developed here. ...
Onsite non-potable reuse (NPR) is a way for buildings to conserve water using onsite sources for uses like toilet flushing, laundry and irrigation. Although early case study results are promising, aspects like system suitability, cost and environmental performance remain difficult to quantify and compare across broad geographic contexts and variable system configurations. In this study, we evaluate four NPR system types – rainwater harvesting (RWH), air-conditioning condensate harvesting (ACH), and source-separated graywater and mixed wastewater membrane bioreactors (GWMBR, WWMBR) – in terms of their ability to satisfy onsite non-potable demand, their environmental impacts and their economic cost. As part of the analysis, we developed the Non-potable Environmental and Economic Water Reuse Calculator (NEWR), a publicly available U.S. EPA web application that allows users to generate planning-level estimates of system cost and environmental performance using location and basic building characteristics as inputs. By running NEWR for a range of scenarios, we find that, across the U.S., rainfall and air-conditioner condensate are only able to satisfy a fraction of the non-potable demand typical of large buildings even under favorable climate conditions. Environmental impacts of RWH and ACH systems depend on local climate and were comparable to the ones of MBR systems where annual rainfall exceeds approximately 10 in/yr or annual condensate potential exceeds approximately 3 gal/cfm. MBR systems can meet all non-potable demands but their environmental impacts depend more on the composition of the local energy grid, owing to their greater reliance on electricity inputs. Incorporation of thermal recovery to offset building hot water heating requirements amplifies the influence of the local grid mix on environmental impacts, with mixed results depending on grid composition and whether thermal recovery offsets natural gas or electricity consumption. Additional environmental benefits are realized when NPR systems are implemented in water scarce regions with diverse topography and regions relying on groundwater sources, which increases the benefits of reducing reliance on centralized drinking water services. In terms of cost, WWMBRs were found to have the lowest cost under the largest range of building characteristics and locations, achieving cost parity with local drinking water rates when those rates were more than $7 per 1000 gallons, which occurred in 19% of surveyed cities.
... Such publications were mainly based on surveys of community groups using greywater recycling systems or considering this solution in their place of residence [119]. Further interest in the topic resulted in publications addressing the implementation of greywater recycling techniques with consideration of minimizing investment costs [120]. In recent years, greywater recycling has received a lot of attention from both researchers and potential users. ...
The use of greywater reduces the consumption of many resources and is an effective tool for achieving Sustainable Development Goals. In order to assess the rationality of its use as an alternative source of energy and water in buildings, a holistic literature review was carried out based on a bibliometric analysis of publications in these fields. The main bibliographic source was the Web of Science database. This review contributed to a better understanding of the analyzed research field. It also revealed trends in greywater energy recovery and recycling research, indicating that these are developing fields. In recent years, there has been a marked increase in the number of publications on the most popular ways of using greywater in buildings, with the territorial scope of research carried out in the greywater recycling domain being considerably larger than research on greywater energy recovery. The analysis revealed poor cooperation between different universities, especially in the field of greywater energy recovery. In light of previous literature reviews, some important research gaps and further proposals for future research were also identified. They concern, in particular, the simultaneous use of greywater as an alternative source of energy and water. Together with the findings of other researchers and people related to the subject matter, this review can contribute to the further development of greywater energy recovery systems and greywater recycling systems.
... Among the reviewed LCA studies that compared rainwater-harvesting systems [168][169][170] or integrated systems (rainwater and greywater reuse) [171][172][173] with centralised systems, as usual, the majority reported the alternative systems showed better environmental performance than the conventional ones. However, in the work of Chang et al. [172], although the integrated rainwater and greywater system had shown lower greenhouse gas emissions, it presented an energy demand equal to that of the conventional process. ...
The feasibility of installing rainwater harvesting systems in buildings is usually defined based primarily on economic analysis. In this perspective, we reviewed the literature related to water consumption in buildings, rainwater use, and environmental assessment tools to evaluate the impact of rainwater harvesting on the environment. Identifying water end uses in buildings showed a high potential for potable water savings through alternative sources (e.g., rainwater use for non-potable purposes). Most studies reviewed found potential for potable water savings from 20 to 65%. Moreover, the literature reported that rainwater harvesting systems might reduce the runoff volume from 13 to 91%. However, other possible benefits and impacts of the systems on water flow and the environment must be assessed in addition to the potential for rainwater harvesting. Life cycle assessment, life cycle cost assessment, and water balance modelling have been used in urban water management. Most life cycle studies reported that rainwater harvesting systems have better environmental performance than centralised systems. The water balance method may effectively determine the impacts these systems cause on the water cycle. Using life cycle assessment and the water balance method together is essential to evaluating rainwater harvesting systems integrated into the urban environment.
... One such alternative management strategy is to implement buildingbased decentralized water treatment solutions as a supplement to centralized water systems (Derrible et al., 2021). By diversifying the portfolio of water sources such as harvested rainwater and recycled greywater, decentralized water treatment in buildings can help reduce the volumes of water withdrawn from the environment (Marinoski and Ghisi, 2019;Yu et al., 2015). Decentralized water treatment in buildings can also reduce pumping energy use by placing the treatment units adjacent to the point of use and by providing fit-for-purpose water supplies (Hendrickson et al., 2015). ...
Decentralized water technologies such as rainwater harvesting (RWH) and greywater recycling (GWR) can supplement centralized urban water systems, helping reduce water withdrawal and improve water reliability. These benefits only emerge when decentralized water technologies are widely implemented. Several decision-supporting frameworks have been developed to identify suitable locations for deploying decentralized water technologies in a city. Yet, the support remains inadequate regarding: 1) the evaluation of the trade-off between environmental benefits and economic costs in selecting locations, and 2) the interpretation of the transition of optimal selections from low to high investment to assist in the promotion. This study presents an integrated analytic framework that combines multi-objective optimization and data-driven interpretation to direct the city-wide sustainable promotion of building-based decentralized water technologies. We select single-family houses in the city of Boston and apply the framework to study the promotion of building-based RWH and GWR. The framework starts with multi-objective spatial optimization to identify the non-dominant optimal selections (i.e., Pareto-front) of houses and technologies at the trade-off between maximizing energy savings and minimizing financial investment. Then, we evaluate the impact of the initial selection setting and the community-based maximum water saving constraint on the Pareto-optimal front. The spatial optimization shows that RWH is much more applicable than GWR for single-family house communities in Boston. When interpreting the Pareto-front, two clusters of census blocks stand out based on the change in the percentages of houses selected to invest RWH and GWR in each census block along with different investment levels. One cluster demonstrates its priority of being first selected to deploy RWH. Using Random Forest, critical features explain why one cluster should be selected first for promotion, including the larger demand for non-potable water use, longer distance from the centralized facilities, and larger rooftop for collecting rainwater. Finally, we discuss possible future improvements of the proposed spatial optimization and interpretation framework. Overall, our study can be useful to promote decentralized water technologies in cities.
... In addition, the analysis of hybrid systems has been limited to residential and commercial structures, with a focus on water conservation and environmental impacts. Marinoski and Ghisi (2019) proposed a technique for evaluating the performance of an HRG in a single-family residential building in Brazil using a life cycle assessment (LCA). The HRG achieved a 41.9% watersaving proficiency, a 40% draining cutback rate, and a 36.1% energy utilization cutback rate, according to the findings. ...
The transition from a linear make-use-dispose model to a Circular Economy (CE) model has gained momentum in recent years. To date, substantive efforts have been put by researchers and practitioners on environmental assessment of circular water systems (CWS). Yet, the economic aspect of CWS has not received the same attention. This research is an attempt to bridge this gap by evaluating the economic viability of a decentralised hybrid rainwater- wastewater-greywater (HRWG) system. For this purpose, a framework of Shadow Pricing- Life Cycle Cost-Benefit (SLCCB) to analyse a CWS is proposed. Shadow pricing could compliment the established Life Cycle Costing (LCC) methods. The main parameters (costs and benefits) of the proposed SLCCB framework are divided into two types: Internal and External. The Internal pricing covers the capital expenditure (CAPEX) and operational expenditure (OPEX), while the External pricing covers the environmental and social costs-benefits of implementing CWS. The proposed SLCCB added to the classical Net Present Value (NPV) and Payback Period (PP) calculations could provide a more realistic evaluation of the economic performance of CWS. To demonstrate the efficacy of the new CE model, a new CWS in Greece was studied.
A sensitivity analysis was conducted to assess the impact of the reclaimed water tariffs, internal costs, life span of the project, and the annual discount rate on the SLCCB. The results of the study reveal that the SLCCB of CWS is highly sensitive to these parameters. The economic feasibility of CWS boost with increasing discount rate and reclaimed water tariffs, as well as with decreasing project's life span and internal costs. The conclusion of this research demonstrates that investment in CWS is economically viable if External parameters are taken into consideration.
... Rooftop rainwater harvesting in residential areas has received notable consideration as an alternative water supply source, and numerous research studies have been conducted all over the world [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In an urban context, two prime focuses of rainwater harvesting analysis are reliability and water saving potential [10]. ...
Despite numerous studies on residential rainwater tank, studies on commercial rainwater tank are scarce. Corporate authorities pay little heed on this sustainable feature. With the aim of encouraging corporate authorities, this study presents the feasibility and economic benefits of rainwater harvesting (RWH) in commercial buildings in the capital city of Bangladesh, where water authority struggles to maintain town water supply. The analysis was conducted using a daily water balance model under three climate scenarios (wet, dry and normal year) for five commercial buildings having catchment areas varying from 315 to 776 m2 and the storage tank capacity varying from 100 to 600 m3. It was found that for a water demand of 30 L per capita per day (lpcd), about 11% to 19% and 16% to 26.80% of the annual water demand can be supplemented by rainwater harvesting under the normal year and wet year climate conditions, respectively. The payback periods are found to be very short, only 2.25 to 3.75 years and benefit–cost (B/C) ratios are more than 1.0, even for building having the smallest catchment area (i.e., 315 m2) and no significant overflow would occur during monsoon, which leads to both economic and environmental benefits. Though the findings cannot be translated to other cities as those are dependent on factors like water price, interest rate, rainfall amount and pattern, however other cities having significant rainfall amounts should conduct similar studies to expedite implementations of widescale rainwater harvesting.
... The system function was considered to be the water supply in residential buildings of the city, therefore, the functional unit was the water supply in m 3 . Twenty years was considered to be the time horizon, as observed in other research works regarding permeable pavements and hydraulic systems [37,38]. The system boundary comprised the production of materials and components for the systems, including extraction of raw materials and processing, replacement of components over the lifespan of the systems, electricity consumption for system operation, and final disposal of components at the end of the system lifespan, considered to be a sanitary landfill, exclusively for construction debris. ...
While rainwater harvesting can provide additional water resources, this approach is largely undertaken using water from roofs. More recently, the potential for using stormwater harvested from permeable pavements was recognised as a potential additional water resource. The objective of this study was to estimate the reduction of environmental impacts caused by traditional drainage systems and centralised water utilities if permeable pavement systems were used to harvest stormwater for nonpotable purposes in buildings. The lifecycle environmental impacts and costs associated with the proposed pavements and hydraulic systems were assessed. The city of Glasgow was chosen as a case study. We used the Netuno computer programme to estimate the potential for potable water savings considering the use of stormwater for nonpotable purposes and the SimaPro software to perform a lifecycle assessment (LCA). With the implementation of permeable pavements and stormwater utilisation, great reductions in lifecycle emissions (i.e., CO 2-, SO 2-, and PM 2.5-equivalent emissions) were observed. The proposed system also proved to be economically feasible, i.e., a payback period equal to 16.9 years. The results show the economic and environmental feasibility of permeable pavements when used on a large scale, proving to be an important strategy to reduce water and environmental stresses caused by centralised water utilities and traditional drainage systems.
... Less important factors included the vegetation type and presence in removing E. coli, however, the study determined new vegetation options other than conventional biofilter/wetland plants. Marinoski and Ghisi (2019) assessed the environmental performance of hybrid rainwater-graywater systems in low-income houses in a community in Brazil using a life cycle assessment model. Two water supply scenarios, houses with a hybrid rainwater-graywater system and houses with only a potable water supply, were evaluated in terms of their environmental impact. ...
This section presents a review of the scientific literature published in 2019 on topics relating to distributed treatment systems. This review is divided into the following sections: constituent removal, treatment technologies, planning and treatment management, and other topics.
Practitioner points
• Highlights changes and innovation in removal techniques and technologies in water treatment.
• Reviews management systems of distributed treatment systems.
• Discusses point‐of‐use treatment systems.
... The computer programme Netuno was used; it estimates the potential for potable water savings for different tank capacities, according to the user-defined limits (Ghisi and Cordova 2014). The sizing of rainwater tanks using Netuno has already been addressed by several studies such as those of Ghisi and Ferreira (2007), Berwanger and Ghisi (2014), and Marinoski and Ghisi (2019). ...
This study investigates the potential for potable water savings by using rainwater in a home in Blumenau, southern Brazil. The water end-uses were estimated based on frequency and time of use of the water appliances. The water flow rates were measured using containers and a stopwatch. Besides the estimated water consumption, daily measurements were taken using a water meter. The water consumption estimated was compared with the consumption measured and the water end-uses were obtained. The water for activities that did not require potable water accounted for 46.5%. This percentage was used as input data in the Netuno computer programme along with other parameters for the design of a rainwater harvesting system. The use of rainwater in the house, using a 2,000-litre tank, would provide potable water savings equal to 44.8%. This study demonstrated that there is a great potential for the use of rainwater in single-family houses in Blumenau.
... Climate, as well as social and economic changes, has forced society to continually adapt to water shortages [6][7][8]. Various strategies have been developed and improved in the last decades to mitigate water shortage, such as rainwater harvesting [9][10][11][12], greywater use [13], and hybrid rainwater-greywater systems [14]. ...
The objective of this study is to evaluate the potential for potable water savings by using rainwater in the residential sector of Joinville, a city located in southern Brazil. Data on roof areas of residential buildings were obtained from the Joinville city council. By considering the roof areas and typologies of residential buildings, representative models were created. The following parameters were used to determine the rainwater tank capacity: the number of dwellers; the total daily water demand per capita; and the rainwater demand. To carry out the simulations for determining the optimal rainwater tank sizes and potential for potable water savings, the computer program Netuno was used to run 33,720 different scenarios. By considering the occurrence percentage for each representative building model (weighted average), the average potential for potable water savings by using rainwater was calculated. The average potential in the central region of Joinville was 18.5% when there is rainwater use only in toilets, and 40.8% when there is rainwater use in toilets and washing machines. The rainwater harvesting system showed a better performance for a rainwater demand equal to 20% of the total daily water demand. The results indicate the necessity to properly size rainwater tank capacities to meet water demands, thereby encouraging more people to adopt rainwater harvesting as an alternative source for non-potable water in buildings. The demand for rainwater should be carefully evaluated, especially in multi-story residential buildings, due to the low availability of roof areas.
Hybrid rainwater-greywater systems (HRGs) are efficient decentralized water reuse systems with a profound potential for conserving water in buildings. However, the economic unfeasibility of HRGs has hindered their implementation. Methods to improve the economic benefits of HRGs have rarely been explored. This study proposes a comprehensive economic analysis based on the cooperative theory to explore the economic potential of HRGs. An HRG on campus in Japan was selected as a case study to evaluate its water-saving performance. The economic feasibility of the HRG was then analyzed based on the life cycle cost model. Finally, considering that the implementation of the HRG weakened the profit of the main water plants, the cooperative feasibility and driving factors between the HRG and main water plants were explored in terms of mutual benefits based on the cooperative theory. The results highlight that the construction costs significantly reduce the economic benefits of HRGs. HRGs have more substantial economic benefits in cooperation than in non-cooperation. In addition, the subsidy of the government for HRGs makes it easier to drive the success of the cooperation. This study not only provides a new idea for improving the economic feasibility of HRGs but also provides policy orientations to the government to promote decentralized water reuse systems.
Urban water systems (UWS) comprise both the existing freshwater ecosystems and the water infrastructure that humans have built to (i) collect, store, treat, and supply water for potable and non-potable uses; (ii) collect, transport, and treat the generated wastewater; and (iii) discharge treated or untreated water to freshwater ecosystems. Analysing UWS emissions, resources, and energy consumption in an integrated manner using life cycle assessment (LCA) is of paramount importance to make wise decisions at the urban scale reaching optimal design, construction, and operation. In this chapter we provide an overview of LCA studies applied to UWS and describe challenges in this field first as a state of the art and second through 3 case studies which balance construction and operation inventories and include different elements of the UWS. The evaluation of water management scenarios in cities becomes more realistic as more UWS elements are included; making conclusions about scenarios of one particular element without considering the entire UWS might lead to misleading conclusions as the elements impact each other in a cascading effect. LCA is well established for wastewater treatment and guidance is now available for practitioners. Similar guidance is needed for other UWS elements (drinking water production, wastewater reuse, etc.) and for their integration.
As mudanças climáticas e o aumento da população urbana são fortes estressores para os recursos hídricos, fazendo-se necessário dialogar sobre a construção de sistemas urbanos resilientes e sensíveis à água. Desse modo, o aproveitamento de águas pluviais se apresenta como importante alternativa de acesso à água e de redução das pressões nos mananciais. Esta pesquisa objetivou identificar a potencialidade da captação da água de chuva em treze cidades do Estado da Paraíba por meio de simulações computacionais. Foram adotados doze cenários para cada cidade e verificou-se que a captação de águas pluviais nos locais de estudo é viável para diminuir a demanda de água potável, contribuindo para o abastecimento descentralizado de água e o aumento da resiliência urbana. Por fim, entende-se que, quando agregada ao planejamento urbano, esta tecnologia tende a favorecer cidades menos vulneráveis hidricamente.
Rainwater harvest is a desirable alternative clean technology where water is scarce, but the economic viability of its implementation is reduced by the need to install pumps and pipes. The type of filter bed and the frequency of filter changes can increase costs, compromise the quality of the water obtained by this treatment and increase the environmental impacts. This study focuses on a system for collecting and treating rainwater that is compact, innovative, dispenses with the use of pumps, and can be adapted for use in homes and industries, contributing to clean production. An acrylic blanket (Acrylon) was used as a filtering medium because it is a low-cost alternative and is easy to obtain and handle. The experiment was carried out in a company located in the industrial city of Itaboraí (Rio de Janeiro). Water characterization was monitored before and after contact with the roof, and after passing through the treatment equipment (11 rain events). Samples were collected in triplicate; the first sample was collected within 10 min of the onset of rain (first flush), the second after 15–30 min of rain, and the third after 30 min of rain. The second and third samples were used to generate a “continuous” sample. The evaluated parameters were turbidity, apparent color, hydrogenionic potential, temperature, free residual chlorine, and the presence of coliforms (total and tolerant). The apparent color removal efficiency was 81.70% for first flush and 49.54% for continuous samples, and the turbidity removal efficiency was 74.28% and 52.19%, respectively. These removal efficiency results are similar to those achieved by traditional rainwater treatment systems that do not discard the first flush. It was found that the treatment met the requirements of the Brazilian standard for the use of rainwater based on turbidity (less restrictive standard), residual chlorine, and absence of coliforms, but did not meet the requirements for hydrogen potential and color removal.
Due to the increasing population and the need for water resources, it is necessary to take measures to reduce water consumption. Water demand management is known as a solution to the problem of water shortage. Water demand management can have an impact on various sectors, including the environment, energy, and even urban infrastructure, by affecting the amount of water consumed. As an example of effects on urban infrastructures, impacts on the hydraulics of the sewerage network due to the reduction of water consumption and consequently the produced wastewater could be mentioned. Reducing the amount of wastewater produced and thus reducing the velocity of sewers and reducing the height to depth ratio in sewer pipes can lead to clogging, sedimentation, odor, and corrosion. By considering this issue, the design and renovation of sewer networks could be optimal and economic benefits could be achieved. Therefore, evaluating the impact of water demand management policies on water and wastewater infrastructure could be very important in their proper management and operation. In this regard, the main goal of this study is to evaluate the mentioned hydraulic effects. Results indicate a change in the hydraulic conditions of the sewer network, including the velocity in the pipes and their filling percentage. The results of this research and its generalization to metropolitan areas could provide a proper point of view for managers and designers of sewerage networks.
Due to the current deterioration of the environment, the performance degradation of reinforced concrete rainwater drainage pipes (RCRDPs) has become increasingly serious. Aiming at these problems and to provide the experience and ideas for scientific management of the pipelines, this study established an evaluation model for the performance of RCRDPs based on the combined weight-fuzzy theory. This study determined the evaluation index system and classification level boundaries, the subjective and objective weights of each index, the fuzzy evaluation matrix, and the performance level of the pipeline system. In addition, according to the radar chart analysis method, the performance of the cases was ranked and the specific repair plans were obtained. Finally, the scientific evaluation method was tested with the case study of 20 pipelines of DoaQung City. The research results show the following: (1) The combined weight of each indicator of the pipelines fully reflects the importance of them, overcoming the subjectivity of the analytic hierarchy process (AHP) and adopting the objectivity of the entropy theory. (2) The ranking of 20 pipelines comprehensive performance levels is G>F>Q>D>H>S>B>E>N>C>K>P>L>R>A>O>J>M>I>T, and this almost the same as the result of closed-circuit television inspections (CCTV). (3) The combined weight-fuzzy theory can be based on CCTV data to compare the status of each index, and the evaluated results are relatively scientific and reasonable. This research can provide a theoretical reference for the performance classification and maintenance of RCRDPs.
The development of hybrid rainwater-graywater systems (HRG) has greatly alleviated urban water scarcity. However, the HRGs in public buildings have rarely been explored, which had limited the popularity of hybrid systems. In this study, a campus in Japan was selected to evaluate the feasibility of HRGs in public buildings. A water balance model with an hourly time step was performed to quantify the performance of the rainwater and graywater subsystems in the HRGs. Second, the electricity consumption of the HRGs was evaluated. Then, a detailed life cycle cost model was designed to calculate the economic benefit of the HRGs under the current and optimization scenarios. Finally, the results obtained are compared with HRGs in residential and commercial buildings to discuss the advantages of HRGs in public buildings. The results indicate that the promotion of HRGs in public buildings can not only achieve higher water-saving efficiency than other building types but also reduce electricity consumption in comparison with the traditional water supply methods. The economical unfeasibility of HRGs is caused by the waste of excess reclaimed water and high maintenance costs. HRGs in public buildings has the potential to be promoted preferentially in regions where the water tariff is higher than 880 JPY/m³ or the non-potable water tariff is set to at least 200 JPY/m³.
Clean water is becoming an increasingly scarce resource, and its availability is already compromised in many cities. Several techniques for increasing urban water availability are under consideration, but how their life cycle environmental impacts compare amongst one other remain largely unknown. For cities in developing countries, which are more susceptive to water shortages, this is particularly true. Furthermore, to directly compare these technologies, they must be evaluated using the same methodological framework. This paper compares, for the first time, the life cycle environmental impacts of the following three techniques: i) seawater desalination by reverse osmosis (SWRO); ii) indirect potable wastewater reuse (IPR) through an upflow anaerobic sludge blanket digestion reactor, oxidation ditch, ozonation, and managed aquifer recharge; and iii) rainwater harvesting (RWH) to substitute drinking water from the local distribution network. These techniques were evaluated in the Brazilian southern city of Florianópolis. Life cycle assessment (LCA) was used to calculate 15 environmental impact categories with the ReCiPe methodology. Variations in electricity consumption according to technical developments, effluent quality, and pumping efficiency were taken into consideration with parametric analysis. Furthermore, a sensitivity analysis was carried out regarding the direct emissions of methane and nitrous oxide during IPR, and the electricity mix. SWRO indicates the highest results for 12 out of the 15 impact categories, and IPR indicates the lowest values in nine categories. Electricity consumption is the main contributor to most impact categories during SWRO and IPR. Out of six categories (including climate change and human toxicity), RWH is the preferable option whilst comparatively also presenting the worst results for water depletion and marine eutrophication, with glass fibre produced for storage tanks being the main contributor. In the climate change potential category, for instance, SWRO, IPR and RWH have mean results of 751, 998, and 591 kg CO2 eq./1,000 m³, respectively. However, the sensitivity analysis showed that if direct emissions of CH4 and N2O in IPR are low, then the IPR technique will have better results than the SWRO method, resulting in 710 kg CO2 eq./1,000 m³. Additionally, the country electricity mix was found to be highly influential in the environmental impacts, especially for SWRO and IPR. The results obtained from this research will inform stakeholders, particularly those in developing countries, about possibilities of adopting new techniques for increasing water supplies, without comprising the environmental sustainability of these systems.
Técnicas como aproveitamento de águas pluviais e reuso de águas cinzas apresentam-se como importante ferramenta de gestão ambiental, principalmente em regiões que possuem característica de escassez de recursos hídricos, a exemplo da região semiárida brasileira. No intuito de verificar a viabilidade dessas técnicas, esse trabalho avaliou duas propostas de projetos de reaproveitamento num bloco universitário, localizado na região semiárida do estado de Pernambuco. Num primeiro caso (Caso A) os reservatórios de acumulação de águas pluviais e cinzas foram dimensionados separadamente. No segundo caso (Caso B), foi considerado um único reservatório para armazenamento dessas águas. A viabilidade econômica para implantação dos sistemas foi avaliada a partir do cálculo do tempo de retorno e do valor presente líquido (VPL). Foi verificado que ambos os projetos são viáveis quanto ao tempo de retorno do investimento e racionalidade no uso água, não sendo evidenciadas diferenças significativas entre os mesmos. Economic viability of implementing greywater and rainwater reuse systems in a university block in the Brazilian semiarid A B S T R A C TTechniques such as rainwater harvesting and greywater reuse are important environmental management tools, especially in regions with scarce water resources, such as the Brazilian semiarid region. To verify the viability of the techniques, this work evaluated two proposals for reuse projects in a university block, located in the semiarid region of the state of Pernambuco. In the first case (Case A) the rainwater and greywater accumulation reservoirs were sized separately. In the second case (Case B), it was considered a single reservoir for the storage of the waters. The economic viability for the system's implementation was evaluated by calculating the payback and the Net Present Value (NPV). It was found that both projects are viable in terms of return on investment time and rational use of water, with no significant differences between them.Keywords: water scarcity; residual waters; storage; Rippl's method; payback.
El objetivo central del libro blanco que se presenta a continuación es mostrar un camino para contar con una estrategia efectiva para la reducción de la huella de carbono de las ciudades y hacer frente a los impactos y riesgos del cambio climático. Se analizan las políticas, regulaciones y capacidades requeridas para que los proyectos urbanos puedan avanzar hacia una mayor sostenibilidad. También se identifican las posibilidades de financiación para la implementación de medidas de mejora seleccionadas. Este análisis y las recomendaciones realizadas se basan en la investigación “Systemic perspectives on low-carbon cities in Colombia- An integrated urban modeling approach for policy and regulatory analysis”, liderada por la Universidad de los Andes en el marco del financiamiento UK-PACT Colombia.
Water reuse can contribute to reducing pressures on water resources, as an important approach and practice, reducing the demand for potable water for purposes not requiring high quality water. With water resources being depleted and the demand for water increased, grey water reuse becomes more popular in order to preserve water worldwide. This paper presents a comprehensive review of all significant research and reviews existing case studies to review the present knowledge with respect to the characteristics of grey water. The main summary table covers 63 works that focus on the application of these methods to different fields of sustainable building design. Key fields are reviewed in detail: grey water, including water reuse; grey water recycling; water sustainability; building design optimization; and wastewater of several areas simultaneously, with particular focus on buildings. This research aims to introduce the review of the researches that covered the grey water management. Various engineering databases, international journals, and conference proceedings were searched. International journals were searched for relevant research papers. This paper provides perspectives on grey water context in order to frame the breadth and multiple dimensions it encompasses, to summarize recent activities on selected relevant topics, and to highlight possible future directions in research and implementations.
In a scenario of water crisis, such as that experienced by the Brazilian Agreste region in recent years, the sustainability of water supply has been the aim of several investigations. This research project involved the study of the hypothetical implementation of technological alternatives for reducing household potable water consumption in Caruaru, PE. The alternatives were evaluated from a multicriteria perspective. That perspective takes into account environmental, technical, economic and social criteria, which are identified through designs, market research and interviews with residents and experts. With the application of the multicriteria method Promethee II, it was possible to verify that the implementation of water-saving devices is the most suitable alternative for the region. This alternative promotes a 29.11% reduction in water consumption, while the payback period was estimated at 16 months. The long term required to recover the capital in the other alternatives highlights the need for government policies offering financial incentives to the population, preventing the region’s socioeconomic conditions from being the main obstacle for the adoption of water resources conservation practices.
This paper presents an optimization framework to design an intensified and integrated residential complex that involves satisfying demands and using wastes. The problem is addressed by evaluating distinct allocation schemes (social welfare, Rawlsian welfare, Nash, and Rawlsian-Nash allocation) to identify solutions when the objective functions are considered as stakeholders of the system. To find the optimal design of the complex with the minimum amount of resources, the minimization of the total cost, the freshwater consumption, and the generated emissions are included as objective functions. To fulfill demands (water, electricity, heating, and cooling) and treat the generated wastes, distinct alternatives are considered, such as rainwater harvesting, water treatment and recycling, cogeneration, gasification of solid wastes, and algae cultivation. The resulting formulations are mixed-integer linear and mixed-integer nonlinear programming models. The applicability of the formulation was demonstrated through a case study of a residential complex in Mexico. Results show several optimal solutions that favor distinct stakeholders depending on the evaluated scheme. We also find that the only scheme that gives preference to two objectives is the Nash formulation. When specific weights for the objectives were included, alternative allocations guided simultaneously by the weighting factor and the scheme are found as well.
Recently, net-zero buildings (NZBs) have specially attracted the attention of researchers due to their high performance in saving energy and reducing environmental impacts. A zero energy building (ZEB) and zero water building (ZWB) are nearly neutral buildings with very high energy and water performance that can greatly reduce the energy and water usage and consequently mitigate carbon emissions. Such system is achievable through balancing energy needs supplied by solar or other renewable energy sources. However, so far, no precise method for designing, operating, and controlling this type of building has been provided to achieve net ZEB and net ZWB goal. NZB is significantly effective in reducing greenhouse gas (GHG) emissions, total energy and water consumption, and utilization cost for building owners. The main purpose of this chapter is to examine various existing net ZEBs and net NZWBs frameworks, assess the progress and implementations of the NZEB and NZWB, review development policies for design and operation worldwide, interrelationship among net ZEB and net ZWB, as well as study areas that have potential for developing net ZEBs and net ZWBs.
Egypt is a country with limited water resources. Egypt water needs are growing rapidly as a result of the population increase, climate change and development activities. The aim of the study is to analyse how Egypt can sustain its mega urban projects by utilizing greywater as a non-conventional water resource. A quantitative-based assessment has been conducted to investigate the overall evaluation of the greywater resources in Egypt. Greywater accounts for between 40 and 80% of the total water discharged from the house, and the total use of water for drinking and health use can be estimated at 10.4 billion cubic meters per year. The results show that the greywater resources may support a sustainable future of non-conventional water resources in a very positive way. Greywater can provide Egypt with about 4.15–8.30 billion cubic meters annually, which is a good support for water resources in Egypt. The paper concluded that greywater is an important resource to facilitate the success of the new mega urban projects. Egypt should maximize the share of greywater resources, especially in its new mega urban projects. Greywater resources can support Egypt and other arid and semiarid regions and countries in transition to a sustainable future.
Recently, net-zero buildings (NZBs) have specially attracted the attention of researchers due to their high performance in saving energy and reducing environmental impacts. A zero energy building (ZEB) and zero water building (ZWB) are nearly neutral buildings with very high energy and water performance that can greatly reduce the energy and water usage and consequently mitigate carbon emissions. Such system is achievable through balancing energy needs supplied by solar or other renewable energy sources. However, so far, no precise method for designing, operating, and controlling this type of building has been provided to achieve net ZEB and net ZWB goal. NZB is significantly effective in reducing greenhouse gas (GHG) emissions, total energy and water consumption, and utilization cost for building owners. The main purpose of this chapter is to examine various existing net ZEBs and net NZWBs frameworks, assess the progress and implementations of the NZEB and NZWB, review development policies for design and operation worldwide, interrelationship among net ZEB and net ZWB, as well as study areas that have potential for developing net ZEBs and net ZWBs.
Keywords
Net-zero energy building (ZEB) Net-zero water building (ZWB) ZEB design and operation ZWB design and operation Greenhouse gas (GHG)
Rainwater harvesting (RWH) coupled with gravity-driven membrane (GDM) filtration was used to simultaneously treat rainwater and recover energy. A pilot GDM could obtain a relatively stable level of permeate flux (~4.0 L/(m2·h)) under a set water head (ΔH=0.4 m) over 140 days of operation. An increased water head (ΔH=0.6 m) did not achieve a sharp increase in stabilized flux (~2.4 L/(m2·h)) over 20 days of operation until the end. It was found that GDM filtration could produce a permeate that was almost free of particles. However, only a small amount of organic matter and trace metals (i.e., Cr, Al, Fe, Cu, Al, Mn and Ca) were removed, as demonstrated by excitation-emission matrix (EEM) and energy dispersive spectrometry (EDS) analysis. Additionally, the bacterial abundance within the permeate ((8.45±0.11) ×102 cells/mL) decreased compared to that within the GDM tank ((1.85±0.14) ×105 cells/mL), revealing that the rejected bacteria might enhance biofilm formation. The presence of extracellular polymeric substances (EPS), adenosine triphosphate (ATP) and assimilable organic carbon (AOC) indicated a high level of microbial activity within the biofilm, which was also demonstrated by the porous cake layer morphology observed by scanning electron microscopy (SEM) and results from confocal laser scanning microscopy (CLSM) imaging of the biofilm. NH3-N was removed by Nitrospira within the biofilm, which was identified by microbial community analysis. Overall, this novel approach has the potential to improve municipal water availability and stormwater management practices.
A study of water quality parameters was conducted in 38 small-scale roof-harvested rainwater barrels (RHRB) located in urban and peri-urban Philadelphia, USA in winter (November–December) 2014 and summer (June–August 2016). Parameters included two fecal indicator bacteria (FIB) (Escherichia coli and Enterococcus spp.) measured using culture-based methods, eight potential enteric and opportunistic pathogens (Campylobacter jejuni, Acanthamoeba spp., Legionella spp., L. pneumophila, Naegleria fowleri, Pseudomonas aeruginosa, Mycobacterium avium and Mycobacterium intracellulare) measured using quantitative polymerase chain reaction (qPCR), and two metals (lead and zinc) using inductively coupled plasma mass spectrometry (ICP-MS). Fecal indicator bacteria were detected in greater than 60% RHRB samples and concentrations (up to >103 per 100 mL) exceeded US Food and Drug Administration (USFDA) irrigation water quality standards. Among the enteric and opportunistic pathogens tested, 57.9, 44.7, 21.1, 18.4, 5 and 3% were PCR positive for Legionella spp., M. intracellulare, M. avium, Acanthamoeba spp., P. aeruginosa, and C. jejuni, respectively. N. fowleri and L. pneumophila were not detected in any sample. The concentrations of enteric and opportunistic pathogens ranged from 102 to 107 gene copies/L of barrel water. Lead and zinc were each observed in 88.5% of RHRB but the concentrations did not exceed US Environmental Protection Agency (USEPA) standards for irrigating produce, with the exception of one zinc observation (2660 µg/L). Based on these data, it appears that the risk associated with metals in RHRB is likely to be low, as these barrels are only used for gardening and non-potable purposes. However, risks due to fecal and opportunistic pathogens may be higher due to exposure to aerosols during gardening activities and produce consumed raw, and should be investigated further.
This paper presents risk-based enteric pathogen log reduction targets for non-potable and potable uses of a variety of alternative source waters (i.e., locally-collected greywater, roof runoff, and stormwater). A probabilistic Quantitative Microbial Risk Assessment (QMRA) was used to derive the pathogen log10 reduction targets (LRTs) that corresponded with an infection risk of either 10⁻⁴ per person per year (ppy) or 10⁻² ppy. The QMRA accounted for variation in pathogen concentration and sporadic pathogen occurrence (when data were available) in source waters for reference pathogens in the genera Rotavirus, Mastadenovirus (human adenoviruses), Norovirus, Campylobacter, Salmonella, Giardia and Cryptosporidium. Non-potable uses included indoor use (for toilet flushing and clothes washing) with occasional accidental ingestion of treated non-potable water (or cross-connection with potable water), and unrestricted irrigation for outdoor use. Various exposure scenarios captured the uncertainty from key inputs, i.e., the pathogen concentration in source water; the volume of water ingested; and for the indoor use, the frequency of and the fraction of the population exposed to accidental ingestion. Both potable and non-potable uses required pathogen treatment for the selected waters and the LRT was generally greater for potable use than non-potable indoor use and unrestricted irrigation. The difference in treatment requirements among source waters was driven by the microbial quality of the water – both the density and occurrence of reference pathogens. Greywater from collection systems with 1000 people had the highest LRTs; however, those for greywater collected from a smaller population (∼ 5 people), which have less frequent pathogen occurrences, were lower. Stormwater had highly variable microbial quality, which resulted in a range of possible treatment requirements. The microbial quality of roof runoff, and thus the resulting LRTs, remains uncertain due to lack of relevant pathogen data.
Building upon previously published life cycle assessment (LCA) methodologies, we conducted an LCA of a commercial rainwater harvesting (RWH) system and compared it to a municipal water supply (MWS) system adapted to Washington, D.C. Eleven life cycle impact assessment (LCIA) indicators were assessed, with a functional unit of 1 m³ of rainwater and municipal water delivery system for toilets and urinals in a four-story commercial building with 1000 employees. Our assessment shows that the benchmark commercial RWH system outperforms the MWS system in all categories except Ozone Depletion. Sensitivity and performance analyses reveal pump and pumping energy to be key components for most categories, which further guides LCIA tradeoff analysis with respect to energy intensities. Tradeoff analysis revealed that commercial RWH performed better than MWS in Ozone Depletion if RWH's energy intensity was less than that of MWS by at least 0.86 kWh/m³ (249% of the benchmark MWS energy usage at 0.35 kWh/m³). RWH also outperformed MWS in Metal Depletion and Freshwater Withdrawal, regardless of energy intensities, up to 5.51 kWh/m³. An auxiliary commercial RWH system with 50% MWS reduced Ozone Depletion by 19% but showed an increase in all other impacts, which were still lower than benchmark MWS system impacts. Current models are transferrable to commercial RWH installations at other locations.
This report describes the results of a collaborative research project undertaken by the Institute for Sustainable Futures, at the University of Technology Sydney, for CSIRO, as part of the Water for a Healthy Country Flagship Collaboration Fund. The objective of the research project has been to examine the energy implications of emerging distributed water infrastructure, the ‘water energy nexus’.
The first phase of this work included a broad literature review of existing research into the water energy nexus, followed by a scoping paper identifying key areas for further research. A number of lot- and estate-scale water systems at sites around Australia were selected as potential case studies and the intention was to conduct a desktop review of their water and energy implications. However, preliminary research showed that existing data was scarce or non-existent. It was therefore decided to complement the research project by carrying out primary research focusing on lot-scale rainwater systems. This additional research has focussed on detailed monitoring and measurement of the energy and water use of eight household systems in Sydney and Newcastle to determine the empirical energy intensity of their rainwater tank systems. In addition, a model has been developed that uses empirical time series water demand data, and actual flow versus power curves for typical rainwater tank pumps to estimate the energy intensity for different pump and end use combinations.
Existing research into the energy use of water infrastructure has primarily focused on large-scale centralised systems, hence, the energy intensity of different aspects of these systems is reasonably well understood. However, there is currently considerable investment in new lot- and estate-scale water infrastructure, including precinct-scale water recycling plants, stormwater harvesting systems, household rainwater tanks and household greywater re-use systems. To date, very little evaluation of these systems has been carried out and the actual operating energy consumption and even water savings of these systems have been the subject of limited investigation.
Household rainwater systems in particular have become increasingly prevalent and their uptake is being encouraged by state and federal government policies. Rebates are being offered to households installing rainwater and greywater systems and in addition, state legislation such as BASIX in NSW requires all new households to reduce their water consumption by up to 40% (depending on location) and over 90% of these households are opting to install a rainwater tank.
This research project has found that the typical energy intensity of the most common single household rainwater tank system has an energy intensity of approximately 1.5 kWh/kL, which compares to a typical figure of less than 1 kWh/kL, for centralised water supply systems and a figure of over 4 kWh/kL for water from large-scale desalination plants. The absolute energy use of a household with a rainwater system will depend on the level of water efficiency of the household.
The energy intensity of water use from rainwater tank systems is very dependent on the pump size, the system configuration, the level of water efficiency and the end-uses to which the tank is connected. End uses that have a low flow, such as toilet cistern refilling, faucet use and leaks have higher energy intensities than end uses such as showers, outdoor water use and bath filling which are typically high-flow end uses. As part of this research project an overall estimate of the energy implications of the large-scale installation of rainwater tank systems has been investigated for Sydney using the data and information collated to provide a comparison with a typical mains water supply system.
This research has identified the need for further measurement of the in-situ energy intensity of different rainwater tank system configurations, to test the impact of pressure vessels, rain switches and variable speed pumps and to estimate the relative cost of these options. There is also a gap in the research regarding appropriate forms of guidelines or policy instruments to encourage best practice efficiency for rainwater tank pumps. Finally, there is a need for further investigation of more complex configurations of distributed water infrastructure including systems in multi-residential and commercial buildings, distributed effluent treatment and reuse systems and neighbourhood scale systems.
By filling these additional research gaps and using standards, guidelines and policy instruments to embed best practice efficiency in rainwater systems and broader water and wastewater distributed systems, the water industry will be able to avoid locking in inefficient systems and tap into the full potential these systems can provide.
Energy and resource consumption required to treat and transport wastewater have led to efforts to improve the environmental sustainability of wastewater treatment plants (WWTPs). Resource recovery can reduce the environmental impact of these systems; however, limited research has considered how scale of implementation impacts the sustainability of WWTPs integrated with resource recovery. Accordingly, this research uses life cycle assessment (LCA) to evaluate how scale of implementation impacts the environmental sustainability of wastewater treatment integrated with water reuse, energy recovery, and nutrient recycling. Three systems were selected: a septic tank with aerobic treatment at the household scale, an advanced water reclamation facility at the community scale, and an advanced water reclamation facility at the city scale. Three sustainability indicators were considered: embodied energy, carbon footprint, and eutrophication potential. This study determined that as with economies of scale, there are benefits to centralization of WWTPs with resource recovery in terms of embodied energy and carbon footprint; however, the community scale was shown to have the lowest eutrophication potential. Additionally, technology selection, nutrient control practices, system layout, and topographical conditions may have a larger impact on environmental sustainability than the implementation scale in some cases.
Managed Aquifer Recharge (MAR) of stormwater has been deemed technically feasible in augmenting the total water supplies of the Adelaide region however, a major obstacle to implementation of new water schemes, particularly for potable reuse, can be gaining public acceptance and political support. The present survey of 1043 Adelaide residents addressed factors identified in the literature such as satisfaction with the quality of water, the importance of cost, perceived effectiveness of the recycled water distribution system, perceptions of community acceptance and trust in the water authorities to manage the system. The study compares three options for the use of stormwater through MAR: non-potable use through a third-pipe system, potable use whereby the water from the aquifer is pumped to a reservoir, and potable use whereby locally treated water from the aquifer is pumped into the mains system. Although respondents were positive about the reuse of stormwater via MAR for both potable and non-potable options and the likelihood of protest was less than ten percent, respondents clearly preferred the non-potable to the potable options. The results suggested a need for public education on issues such as the cost of third-pipe systems, the risks associated with the potable option with localised treatment, and the actual rate of community acceptance, which was higher than they believed. However, there was also evidence of psychological bias, which is not easily moved by the provision of information alone.
Motivated by the desire to understand the impact of water supply systems on the environment, a life cycle-based hybrid methodology is used to assess the performance of two conservation scenarios, water efficiency, and rainwater harvesting, relative to the base case. The analysis carried out for the City of Toronto’s residential sector estimates the operational energy use and GHG emissions, and the embodied burdens associated with water-efficient devices and rainwater tanks. Hydraulic simulations, performed on a hypothetical network to expose the impact of demand peak factor on pressure distribution at nodes, revealed some of the rainwater scenario strengths such as hydraulic stress curtailment and capital investment postponement. While both strategies led to significant water savings, the associated energy expenditures and emissions varied with the selection of system boundaries. Nevertheless, both conservation strategies are worthwhile pursuing for rendering the existing water systems more sustainable.
Although now over 100 years old, the classification of climate originally formulated by Wladimir Köppen and modified by his collaborators and successors, is still in widespread use. It is widely used in teaching school and undergraduate courses on climate. It is also still in regular use by researchers across a range of disciplines as a basis for climatic regionalisation of variables and for assessing the output of global climate models. Here we have produced a new global map of climate using the Köppen-Geiger system based on a large global data set of long-term monthly precipitation and temperature station time series. Climatic variables used in the Köppen-Geiger system were calculated at each station and interpolated between stations using a two-dimensional (latitude and longitude) thin-plate spline with tension onto a 0.1°×0.1° grid for each continent. We discuss some problems in dealing with sites that are not uniquely classified into one climate type by the Köppen-Geiger system and assess the outcomes on a continent by continent basis. Globally the most common climate type by land area is BWh (14.2%, Hot desert) followed by Aw (11.5%, Tropical savannah). The updated world Köppen-Geiger climate map is freely available electronically at http://www.hydrol-earth-syst-sci.net/????.
The major limitation of optimization models applied previously for rainwater harvesting (RWH) systems is the systematic evaluation of environmental and human health impacts across all the lifecycle stages. This study integrated life cycle assessment (LCA) into a multi-objective optimization model to optimize the construction areas of green rooftops, porous pavements and green lands in Beijing of China, considering the trade-offs among 24 h-interval RWH volume (QR), stormwater runoff volume control ratio (R), economic cost (EC), and environmental impacts (EI). Eleven life cycle impact indicators were assessed with a functional unit of 10,000 m² of RWH construction areas. The LCA results showed that green lands performed the smallest lifecycle impacts of all assessment indicators, in contrast, porous pavements showed the largest impact values except Abiotic Depletion Potential (ADP) elements. Based on the standardization results, ADP fossil was chosen as the representative indicator for the calculation of EI objective in multi-objective optimization model due to its largest value in all RWH systems lifecycle. The optimization results for QR, R, EC and EI were 238.80 million m³, 78.5%, 66.68 billion RMB Yuan, and 1.05E + 16 MJ, respectively. After the construction of optimal RWH system, 14.7% of annual domestic water consumption and 78.5% of maximum daily rainfall would be supplied and controlled in Beijing, respectively, which would make a great contribution to reduce the stress of water scarcity and water logging problems. Green lands have been the first choice for RWH in Beijing according to the capacity of rainwater harvesting and less environmental and human impacts. Porous pavements played a good role in water logging alleviation (R for 67.5%), however, did not show a large construction result in this study due to the huge ADP fossil across the lifecycle. Sensitivity analysis revealed the daily maximum precipitation to be key factor for the robustness of the results for three RWH systems construction in this study.
Decentralised rainwater harvesting, greywater recycling, and hybrid rainwater-greywater systems mitigate water scarcity in urban areas. However, data on the mains water savings potential of these systems is not well documented in Malaysia, and real site characteristics are often neglected. The main objectives of this study were to (i) quantify mains water savings potential of six rainwater harvesting systems, two greywater recycling systems, and a hybrid rainwater-greywater system in Malaysia using real site characteristics as inputs to an in-house spreadsheet RainTANK water balance model; (ii) evaluate and recommend optimal connected roof area and rainwater tank volume combinations to maximise yields in rainwater systems; (iii) determine differences in mains water savings potential between domestic and commercial rainwater and greywater systems; and (iv) evaluate the possibility of upgrading an existing rainwater system to a hybrid rainwater-greywater system. Results showed that domestic rainwater systems supplied more than 90% of non-potable water demand for toilet flushing, laundry, and irrigation (i.e. with an overall reliability ranging between 35.5% and 52.5% for the modelled sites), whereas commercial rainwater system supplied less than 43% of non-potable water demand for toilet flushing and irrigation (i.e. with an overall reliability ranging between 11.2% and 22.1% for the modelled sites). Greywater recycling provided overall reliabilities of 21.1% and 41.0% for commercial and domestic systems, respectively, for toilet flushing and irrigation. Domestic rainwater systems had optimal roof areas and tank volumes, whereas commercial rainwater systems can improve rainwater yields by 41-67% by increasing either connected roof area or total rainwater tank volume. Upgrading to a hybrid system increases mains water savings for both domestic and commercial buildings, and maximum overall reliabilities of 32.3%, 57.1%, and 25.1% at Sites 1, 2, and SP, respectively, can be gained from reusing rainwater followed by greywater. A domestic hybrid system should primarily reuse rainwater and supply remaining demand with greywater, whereas a commercial hybrid system should reuse greywater and top-up with rainwater.
Water management plays a major role in any city, but applying alternative strategies might be more or less feasible depending on the urban form and water demand. This paper aims to compare the environmental performance of implementing rainwater harvesting (RWH) systems in American and European cities. To do so, two neighborhoods with a water-stressed Mediterranean climate were selected in contrasting cities, i.e., Calafell (Catalonia, Spain) and Ukiah (California, US). Calafell is a high-density, tourist city, whereas Ukiah is a typical sprawled area. We studied the life cycle impacts of RWH in urban contexts by using runoff modeling before (i.e. business as usual) and after the implementation of this system. In general, cisterns were able to supply > 75% of the rainwater demand for laundry and toilet flushing. The exception were multi-story buildings with roofs smaller than 200 m2, where the catchment area was insufficient to meet demand. The implementation of RWH was environmentally beneficial with respect to the business-as-usual scenario, especially because of reduced runoff treatment needs. Along with soil features, roof area and water demand were major parameters that affected this reduction. RWH systems are more attractive in Calafell, which had 60% lower impacts than in Ukiah. Therefore, high-density areas can potentially benefit more from RWH than sprawled cities.
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The objective of this study is to assess the environmental benefit of using rainwater, greywater, water-efficient appliances and their combinations in low-income houses. The study was conducted surveying twenty households located in southern Brazil, which resulted in water end-uses estimation. Then, embodied energy, potential for potable water savings and sewage reduction when using the different strategies were estimated. The environmental benefit analysis of these strategies was performed using an indicator that includes embodied energy, potable water savings, reduction of sewage and energy consumption in the water utility, and sewage production during the life cycle of the system. The results indicated that the strategy with the greatest environmental benefit is the use of water-efficient appliances, which resulted in substantial water savings and reduction of sewage, causing low environmental impact due to lower embodied energy over the life cycle.
Decentralised hybrid rainwater-greywater systems can switch between climate-independent greywater during dry seasons or climate-dependent rainwater during monsoon seasons, resulting in higher water savings than either rainwater harvesting or greywater recycling systems alone. However, hybrid systems are not widely adopted due to a lack of data on untreated rainwater and greywater quality and a paucity of case studies on pilot-scale systems. This study aimed to monitor untreated greywater quality from two full-scale greywater recycling systems and to assess the performance of a decentralised hybrid rainwater-greywater treatment system operating on a pilot-scale under controlled conditions. Both mixed greywaters sourced from washbasins and ablution activities, and from washbasins, showers, baths, and laundry discharges must be treated prior to reuse: untreated greywater was frequently contaminated with faeces (20/32 samples tested positive for Escherichia coli), and exceeded the allowable Malaysian limits for both recreational waters with body contact (Class IIB) and irrigation waters (Class IV) for total coliforms (27/32), biochemical oxygen demand (BOD5) (19/32), chemical oxygen demand (COD) (12/32), colour (8/32), turbidity (24/32), ammonia (NH3-N) (16/32), phosphates (PO4-P) (28/32), and manganese (Mn) (4/14). Principal component analysis yielded 4 principal components: organic matter from food and body residues; detergents; faecal contamination; and ammonium salts. The pilot-scale hybrid treatment system featured a multimedia filter (MMF), a granular activated carbon filter (GAC), and ozone disinfection. A hydraulic loading rate of 10 L/min produced the highest overall removal efficiencies as longer retention times allowed more pollutant adsorption. Overall, the pilot-scale system removed 52% COD, 53% BOD5, 14% NH3-N, 67% PO4-P, 81% colour, 81% turbidity, 50% total suspended solids (TSS), 53% of total coliforms, 63% copper (Cu), and 29% zinc (Zn) from greywater sourced from a mixture of showers/baths and laundry. The GAC was the most effective at removing COD, colour, turbidity, and Zn. Finally, a series of dilution experiments of greywater with rainwater and mains water was conducted to emulate real scenarios during the practical implementation of hybrid systems with mains water top-up. Greywater dilution had little impact on removal efficiency of colour, turbidity, TSS, and TDS, and dilution of greywater with either mains water or rainwater is recommended to ensure that pH, BOD5, COD, NH3-N, and PO4-P are within Class IIB limits.
Aging water infrastructure and increased water scarcity have resulted in higher interest in water reuse and decentralization. Rating systems for high-performance buildings implicitly promote the use of building-scale, decentralized water supply and treatment technologies. It is important to recognize the potential benefits and tradeoffs of decentralized and centralized water systems in the context of high-performance buildings. For this reason and to fill a gap in the current literature, we completed a life cycle assessment (LCA) of the decentralized water system of a high-performance, net-zero energy, net-zero water building (NZB) that received multiple green building certifications, and compared the results with two modeled buildings (conventional and water efficient) using centralized water systems. We investigated the NZB's impacts over varying lifetimes, conducted a break-even analysis, and included Monte Carlo uncertainty analysis. The results show that, although the NZB performs better in most categories than the conventional building, the water efficient building generally outperforms the NZB. The lifetime of the NZB, septic tank aeration, and use of solar energy have been found to be important factors in the NZB's impacts. While these findings are specific to the case study building, location, and treatment technologies, the framework for comparison of water and wastewater impacts of various buildings can be applied during building design to aid decision making. As we design and operate high-performance buildings, the potential tradeoffs of advanced decentralized water treatment systems should be considered.
This review examines the prospects of a decentralised hybrid rainwater-greywater system to simultaneously alleviate water scarcity and address technical, environmental, and cost constraints. This includes (1) a review on the physicochemical and microbiological characteristics of rainwater and greywater to determine the necessary treatment options; (2) a review of individual components and potential treatment trains for hybrid systems; and (3) an evaluation of configurations for hybrid systems. The literature review reveals that both untreated rainwater and greywater are highly variable in quality and quantity, and so an equalisation basin is proposed to normalise influent into a hybrid system. Both rainwater and greywater should not be reused without treatment due to the presence of pathogens such as Aeromonas, Salmonella, Pseudomonas, and Staphylococcus. Based on the literature, hybrid systems are categorised under three configurations: (a) separate treatments of rainwater and greywater; (b) rainwater reused in washing machines prior to reuse as greywater; and (c) combined treatment of rainwater and greywater. In all three designs, rainwater requires only first-flush diversion and disinfection. Combined rainwater-greywater mixtures should be treated as greywater. Greywater requires chemical, biological, and physical treatment to meet non-potable reuse standards. Chemical processes are effective at removing solids, organics, and surfactants in light greywater, whereas aerobic biological processes are effective at organics removal in mixed and dark greywaters with high organic strength. Physical processes, particularly membrane filtration, are recommended for polishing effluents from chemical or biological treatment as membranes foul frequently and are costly. Subsequently, a combination of ozone or UV with chlorine is recommended to eradicate chlorine-resistant Cryptosporidium oocysts from hybrid rainwater-greywater systems and prevent microbial regrowth.
Ensuring future water security requires broad community support for changes in policy, practice, and technology, such as those involved in delivering alternative water schemes. Building community support for alternative water sources may involve a suite of engagement activities, ranging from information campaigns, through to grassroots and participatory approaches. There is increasing recognition that ‘social capital’—the degree of social connectedness, trust, and shared values within a community—is important for building support for pro-environmental policies. However, little research has examined how social capital might influence support for alternative water schemes. We surveyed a representative sample of Australian adults (n = 5194). Support for alternative water sources was examined using a series of questions focusing on stormwater harvesting, desalination, and recycled water. Involvement in community organisations (defined as participation or membership) was used as an indicator of social capital. Using a series of mediation analyses, we identified that community involvement is associated with support for alternative water sources, and that this effect is mediated by (i) stronger water-related social norms, (ii) greater water-related knowledge, and (iii) increased recall of water-related information. Our results also suggest that these indirect effects can be conditional upon location, employment status, life satisfaction, and language spoken within the home. These findings highlight the importance of social capital in building engagement in water-related issues, and specifically, building support for alternative water sources. In addition they highlight potential pathways for the association between social capital and support for alternative water sources for different social groups and communities.
The water-energy nexus has been increasingly studied in order to elucidate the complex interdependence between water and energy resources, and, as a result, enhance management practices to conserve both resources alike. In this context, integrated water management plans have direct implications on the energy embodied into water and sewerage services. The objective of this study is to assess the potential for energy savings in water and sewerage services by means of on-site integrated water and sewage management strategies in low-income households in Florianópolis, Brazil. The studied water efficient measures include: (i) installation of water efficient fixtures (dual flush toilets and water efficient taps); (ii) reclamation of grey water from shower, washing basin, and laundry for toilet flushing; and (iii) rainwater use for laundry and toilet flushing. From the combination of these measures, the water and energy saving potential of seven integrated water and sewage management strategies were studied. Moreover, the water consumption pattern at ten low-income households with conventional and water efficient taps were empirically determined using water smart meters; whereas, the rainwater supply capacity was estimated by using the computer programme Netuno 4.0, and the grey water supply and sewage reduction capacities were determined using model equations. Rainwater harvesting alone appeared as the least favourable strategy for energy savings as the energy consumption would increase 4% compared to a centralised system; while the combination of water efficient fixtures and grey water reclamation gave rise to the greatest energy saving potential (48%). The findings of this study indicate that, from an energy management point of view, the sustainability of the water sector is primarily associated with the reduction of effluents to centralised systems, rather than the use of alternative water sources.
Life cycle assessment methodology along with water footprint analysis was used to assess the environmental impacts of a domestic rainwater harvesting system (RWH) in France. Firstly, the relevance of substituting drinking water (DW) with rainwater in a private individual household was studied. Secondly, the effect of several parameters namely construction of infrastructures, building scale and disinfection were evaluated. The quantification of environmental impacts was performed using Ecoinvent inventory data and Impact 2002+ evaluation method. The water footprint was assessed through the water stress indicator (WSI). From an environmental standpoint, the RWH system has only slightly higher impact than the DW system. The consumption of electricity for pumping generates the strongest impact. The analysis of the WSI showed that the RWH system can relieve a stress on water resources where it exists. Consideration of infrastructures and disinfection turns environmental impacts significantly higher in all impact categories. Setting up the RWH system at bigger scale, i.e., building scale, is a bit less favoured than the RWH system at household scale. This study aims at pointing out areas of improvement which need to be further studied to make RWH systems more sustainable.
This paper presents an optimization formulation for designing residential water networks involving harvested rainwater and reclaimed wastewater. The design problem is posed as a multi-objective optimization formulation that seeks to balance the objectives of total annualized cost, fresh water consumption, and environmental impact. A life cycle assessment approach is undertaken for estimating the environmental impact. The seasonal dependence of the rainwater is considered in the optimization model. The design approach is applied to a case study for the city of Morelia in Mexico. The results show that significant economic, fresh water consumption, and environmental benefits can be obtained as a result of the proposed approach.
Treatment and water reuse in decentralized systems is envisioned to play a greater role in our future urban water infrastructure due to growing populations and uncertainty in quality and quantity of traditional water resources. In this study, we utilized life-cycle assessment (LCA) to analyze the energy consumption and greenhouse gas (GHG) emissions of an operating Living Machine (LM) wetland treatment system that recycles wastewater in an office building. The study also assessed the performance of the local utility's centralized wastewater treatment plant, which was found to be significantly more efficient than the LM (79% less energy, 98% less GHG emissions per volume treated). To create a functionally equivalent comparison, the study developed a hypothetical scenario in which the same LM design flow is recycled via centralized infrastructure. This comparison revealed that the current LM has energy consumption advantages (8% less), and a theoretically improved LM design could have GHG advantages (24% less) over the centralized reuse system. The methodology in this study can be applied to other case studies and scenarios to identify conditions under which decentralized water reuse can lower GHG emissions and energy use compared to centralized water reuse, when selecting alternative approaches to meet growing water demands.
As a result of the integration of different methodological tools (life cycle assessment and dynamics simulation) and studies to evaluate the economic cost and the potential environmental impact of alternative water supplies (rainwater and greywater) for urban use, the software program Plugrisost (pluvials, greys and sustainability) has been developed. This modelling tool aims to contribute to urban water planning for smart city development. Plugrisost is a simulation model that facilitates the evaluation of rainwater harvesting (RWH) and greywater systems at different scales of urban planning. It is the only tool known thus far to integrate structural elements such as the sizing of storage tanks, estimated cost and quantitative environmental analysis. Plugrisost can be an adequate tool in the design stage because it provides environmental and economic information related to rainwater tank sizing and its estimates are more conservative than those of other tools. Plugrisost contributes to the design of urban infrastructure of low environmental impact, such as infrastructure that incorporates the use of rainwater, and the self-sufficiency analysis of water in cities. Using Plugrisost, we have found that on the single-house scale, the economic viability of an RWH system would be possible if the price of water is greater than 4 Euros/m3; and the environmental analysis would be favourable to tanks with less than 5 m3 of storage capacity. On the apartment-building scale, the results are 1.4 Euros/m3 and 33 m3, respectively.
Increasing stress on water resources is driving urban water utilities to establish new concepts for water supply. This paper presents the consequences of proposed alternative water supply options using a unique combination of quantitative and qualitative methods from different research fields. A former industrial harbor area in Copenhagen, Denmark, is currently under development and all infrastructure will be updated to accommodate 40,000 inhabitants and 40,000 jobs in the future. To reduce stress on water resources it has been proposed to establish a secondary water supply in the area as an alternative to the conventional groundwater-based drinking water supply. Four alternative concepts for a secondary water supply have been considered: 1) slightly polluted groundwater for use in toilets and laundry, 2) desalinated brackish water for use in toilets, laundry, and dishwashers, 3) desalinated brackish water for all uses, including drinking water, and 4) local reclamation of rain and gray water for use in toilets and laundry. The concepts have been evaluated for their technical feasibility, economy, health risks, and public acceptance, while the concepts' environmental sustainability has been assessed using lifecycle assessment and freshwater use impact methods. The holistic assessment method exposes conflicting preference solutions depending on assessment criteria, and reveals multi-faceted consequences for choices in urban water management. Not one concept turns out unambiguously positive based on the evaluation criteria included here, but the systematic evaluation will leave decision-makers informed on the consequences of their choices.
This paper presents an investment feasibility analysis of rainwater harvesting systems for the residential sector in Santa Catarina State, southern Brazil. Five towns were selected for the analysis. Daily rainfall data, average water consumption, rainwater tank costs, water pump costs, and water, sewage and electricity tariffs were obtained for the five towns. Different values for the roof area, number of residents, potable water demand, and rainwater demand were analysed. The rainwater tank capacities were estimated using the Netuno computer programme. The investment feasibility analysis was performed considering the ideal lower tank capacity, as well as capacities smaller and larger than the ideal. Such capacities were obtained according to a variation of six months in the payback period. It was observed that the ideal tank capacity can be conservative for high rainwater demands. In such cases, an investment feasibility analysis should be performed in order to obtain a more appropriate tank capacity. The main conclusion is that rainwater usage is economically feasible for most cases; and the higher the rainwater demand, the higher the feasibility.
To demonstrate the benefits of water conservation at the household level in regional Victoria in Australia, a family house “Sharland Oasis” was designed and built according to an ecologically sustainable design for improved water and energy efficiency. This study has demonstrated that the combined use of alternative water supplies together with water efficient appliances can save up to 77% of total potable water use compared to the average 1990s household water use in the same region considering the location and differing in water use approach. The use of rainwater inside the home alone saved up to 40% of potable water use. In addition to the water savings, there is a significant wastewater discharge saving achieved through the use of water conservation strategies and greywater reuse. A community survey undertaken in regional Victoria revealed that community receptivity for reusing greywater is highest for uses, such as watering gardens and flushing toilets; but it progressively decreased with increasing personal contact with greywater. Positive perception of greywater reuse needs to be encouraged through programs targeted at developing resources, skills and motivation for new water reuse practices and technologies, across a diverse range of social groups.
Rainwater harvesting (RWH) can be used to reduce the demand for potable mains water. At the single-building scale, previous research has focused on water-saving potential, while financial assessment has either been omitted or considered in an ad hoc manner. This paper reports on the application of a more rigorous financial analysis of domestic RWH systems than had been conducted previously. Whole life costing was selected as the most appropriate financial assessment technique. A total of 3840 domestic system configurations were assessed at a daily time step, taking into account various stakeholder perspectives and future cost scenarios. In each case, it was found that harvesting rainwater was significantly less cost effective than relying solely on mains-only water. The domestic RWH systems generally resulted in financial losses approximately equal to their capital costs. Without significant financial support, domestic RWH is unlikely to be cost effective for all reasonably foreseeable scenarios.
Studies on the use of rainwater and greywater to promote potable water savings have been performed in different countries. The main objective of this article is to evaluate the potential for potable water savings by using rainwater and greywater in a multi-storey residential building composed of three blocks, located in Florianópolis, southern Brazil. Water end-uses were estimated by applying questionnaires and measuring water flow rates. An economic analysis was performed to evaluate the cost effectiveness of using rainwater and greywater either separately or together. Results show that the average potential for potable water savings range from 39.2% to 42.7% amongst the three blocks, considering that water for toilet flushing, clothes washing and cleaning does not need to be potable. By using rainwater, the potable water savings would actually range from 14.7% to 17.7%. When greywater is considered alone, potable water savings are higher, i.e., ranging from 28.7% to 34.8%. As for the use of rainwater and greywater combined, the potable water savings range from 36.7% to 42.0%. The main conclusion that can be made from the research is that the three systems that were investigated are cost effective as the payback periods were lower than 8 years, but the greywater system was the most cost effective one, followed closely by the rainwater one.
Rapid urbanization is increasing the amount of hilly communities around many large cities; therefore, saving water pumping energy deserves significant priority. This work proposes optimized rooftop rainwater harvesting systems (RRWHSs) and provides an energy-saving approach for hilly communities. The most cost-effective rainwater tank volumes for different dwelling types are calculated using marginal analysis. The case study at Hua-Chan Community in northern Taiwan indicates that the optimum rainwater tank volumes range from 5 m3 to 10 m3 according to the type of dwelling. The results also reveal that rainwater harvesting becomes economically feasible when both energy and water savings are addressed together. Furthermore, the cost of unit energy saving from RRWHSs is lower than that from solar PV systems. Hence, RRWHSs provide not only water savings, but also as an alternative renewable energy-saving approach to address the water–energy dilemma caused by the ever-growing hilly communities.
A comprehensive case study life cycle assessment (LCA) was conducted of a 7300 m2, six-story building with a projected 75 year life span, located on the University of Michigan campus. The bottom three floors and basement are used as classrooms and open-plan offices; the top three floors are used as hotel rooms. An inventory of all installed materials and material replacements was conducted covering the building structure, envelope, interior structure and finishes, as well as the utility and sanitary systems. Computer modeling was used to determine primary energy consumption for heating, cooling, ventilation, lighting, hot water and sanitary water consumption. Demolition and other end-of-life burdens were also inventoried.The primary energy intensity over the building’s life cycle is estimated to be 2.3×106 GJ, or 316 GJ/m2. Production of building materials, their transportation to the site as well as the construction of the building accounts for 2.2% of life cycle primary energy consumption. HVAC and electricity account for 94.4% of life cycle primary energy consumption. Water services account for 3.3% of life cycle primary energy consumption, with water heating being the major factor, due to the presence of hotel rooms in this building. Building demolition and transportation of waste, accounts for only 0.2% of life cycle primary energy consumption.All impact categories measured (global warming potential, ozone depletion potential, acidification potential, nutrification potential and solid waste generation) correlate closely with primary energy demand.The challenges in developing a life cycle model of a complex dynamic system with a long service life are explored and the implications for future designs are discussed.
Research on rainwater and greywater have been performed all over the world as a way of promoting potable water savings. The main objective of this article is to evaluate the potential for potable water savings by using rainwater and greywater in two houses in southern Brazil. An economic analysis is performed to evaluate the benefits of using rainwater and greywater either separately or together. Results indicate that the potential for potable water savings in both houses range from 33.8% (house B) to 36.6% (house A), considering that water for toilet flushing and washing machine does not need to be potable. By using rainwater, the potable water savings in house A would be 35.5% and in house B, 33.6%. When greywater is considered alone, potable water savings are lower, i.e., 30.4% in house A and 25.6% in house B. As for the use of rainwater and greywater combined, the potable water savings are 36.4% in house A and 33.8% in house B. The three systems that were investigated seem not to be cost effective as the payback periods were very high (above 17 years), but the greywater system was the most attractive one. The main conclusion that can be made from the research is that there needs to be government incentives in order to promote the use of rainwater or greywater in houses in southern Brazil.
The study of emotion has gathered momentum in the field of environmental science, specifically in the context of community resource decision-making. Of particular interest in this review is the potential influence of emotion, risk and threat perception on individuals' decisions to acceptance and adopt decentralised water systems, such as rainwater tanks and greywater systems. The role of message framing is also considered in detail, as well as the influences that different types of framing can have on decision making. These factors are considered as possible predictors for analysing community acceptance of decentralised water in urban environments. Concepts believed to be influenced by emotion, such as trust and framing, are also discussed as potentially meaningful contributors to an overall model of community acceptance of decentralised water. Recommendations are made for how emotion-based concepts, such as risk and threat, can be targeted to facilitate widespread adoption of decentralised systems and how researchers can explore different types of emotions that influence decision making in distinct ways. This review is an important theoretical step in advancing the psycho-social understanding of acceptance and adoption of on-site water sources. Avenues for future research are recommended, including the need for greater theoretical development to encourage future social science research on decentralised systems.
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