Search Results (58)

The objective of this research was to assess the first flush of rainwater harvested from a fibre–cement roof in southern Brazil. Runoff samples were collected for quantifying pH, total suspended solids, turbidity, conductivity, apparent colour, total coliforms, and Escherichia coli. Statistical methods were employed to describe the data, establish correlations between variables, and assess if the antecedent dry weather periods and rainfall intensity affected water quality. The qualitative characterisation of the first flush was performed using principal component analysis and simple regression analyses. The results show that rainwater runoff can be highly contaminated. Hypothesis tests showed that initial rainfall intensity and antecedent dry weather periods affect the quality of the first flush. Principal component analysis suggested that the most significant variables to characterise the first flush were turbidity and apparent colour. Using first-flush diverters in rainwater harvesting systems does not ensure E. coli removal, but it may reduce the risk of users’ contamination. Practical implications include discussions on the suggested first flush and the consequential impact on the quantity and quality of rainwater harvested. Future studies may consider using the method used in this research to develop guidelines based on more samples across the country. As novelty, one includes a statistically robust qualitative study in a region that lacks research on the quantification and quality of first flush. Such assessment helps to build up Brazilian data for a better understanding of first flush management in rainwater harvesting. Full article

Urban water management faces growing pressure from population growth, pollution, and climate variability, demanding innovative strategies to ensure long-term sustainability. This study applies the Life Cycle Sustainability Assessment (LCSA) across four case studies in Brazil and Germany, evaluating integrated systems that combine constructed wetlands for greywater treatment with rainwater harvesting for non-potable use. The scenarios include a single-family household, a high-rise residential building, a rural residence, and worker housing. A multi-criteria analysis was conducted to derive consolidated sustainability indicators, and sensitivity analysis explored the influence of dimension weighting. Results showed that water reuse scenarios consistently outperformed conventional counterparts across environmental, economic, and social dimensions. Life Cycle Assessment (LCA) revealed notable reductions in global warming potential, terrestrial acidification, and eutrophication. Life Cycle Costing (LCC) confirmed financial feasibility when externalities were considered, especially in large-scale systems. Social Life Cycle Assessment (S-LCA) highlighted the perceived benefits in terms of health, safety, and sustainability engagement. Integrated water reuse systems achieved overall sustainability scores up to 4.8 times higher than their baseline equivalents. These findings underscore the effectiveness of decentralized water reuse as a complementary and robust alternative to conventional supply and treatment models, supporting climate resilience and sustainable development goals. Full article

Water stress is a significant issue in many countries, including Portugal, which has seen a 20% reduction in water availability over the last 20 years, with a further 10–25% reduction expected by the end of the century. To address potable water consumption, this study aims to identify the optimal rainwater harvesting (RWH) system for a commercial building under various non-potable water use scenarios. This research involved qualitative and quantitative methods, utilizing the Rippl method for storage reservoir sizing and ETA 0701 version 11 guidelines. Various scenarios of non-potable water use were considered, including their budgets and economic feasibility. The best scenario was determined through cash flow analysis, considering the initial investment (RWH construction), income (water bill savings), and expenses (energy costs from hydraulic pumps), and evaluating the net present value (NPV), payback period (PB), and internal rate of return (IRR). The energy savings obtained were calculated by sizing a hybrid system with an RWH system and a photovoltaic (PV) system to supply the energy needs of each of the proposed scenarios and the water pump, making the system independent of the electricity grid. The results show that the best scenario resulted in energy savings of 92.11% for a 7-month period of regularization. These results also demonstrate the possibility for reducing potable water consumption in non-essential situations supported by renewable energy systems, thus helping to mitigate water stress while simultaneously reducing dependence on the grid. Full article

This study assessed the status of water, sanitation, and hygiene (WASH) services at (49) selected primary schools in uMfolozi Local Municipality, which is situated in the province of Kwa-Zulu Natal in South Africa. Data were collected using an observational checklist tool and by conducting a walk-through survey to inspect the conditions of sanitary facilities, observe the hand-washing practices of the school learners, and analyse the accessibility to safe drinking water in school premises. The data were analysed with the Statistical Package for Social Science Version 29. This study revealed that there is easy access to safe drinking water in all but one school. The dependability of the water supply seemed to be one of the most urgent problems in every school, even though all of them have some kind of drinking water infrastructure on their grounds. Municipal water (n = 25, 36%) and rainwater (n = 25, 36%) were the most common type of water used in schools compared to borehole (n = 15, 22%) and tanker truck water (n = 4, 6%). Schools must have a reserved water supply because of the inconsistent supply of municipal water, and because rainwater is a seasonal harvest while borehole water may be affected by factors like load-shedding. The UNICEF-described ratio of one tap or disperser per fifty learners suggests that the water taps in the schoolyard were insufficient in some schools (n = 25, 36%). Rainwater is collected through a gutter system in the school building roofs and stored in 5000–10,000 Jojo tanks. Borehole water is pumped into Jojo tanks at an elevated position where it is stored, and learners receive the water through taps connected to the borehole tanks. During an emergency when there is no water supply from other sources, tanker trucks are hired to fill tanks that are also used to store rainwater. The borehole and rainwater quality appeared to be clear, but water treatment had not been performed, and the microbial quality was unknown. This shows that the Sustainable Development Goal (SGD) 6, clean water and sanitation, is still far from being met. According to national norms and standards for domestic water and sanitation services, people who do not use water treatment or purification techniques fall in the ‘no service’ category and contribute to the water backlog. Pit latrines (n = 46, 94%) and flush toilet (n = 3, 6%) were found to be the only convenient toilet systems used. The number of toilets is not sufficient according to the guidelines. There are (n = 46, 94%) of the schools in the study area using pit latrine due to insufficient or no water supply. In 89.8% of primary schools, sanitation facilities are in working condition in terms of repair and hygiene, while 10.2% are not usable in terms of hygiene, and these are mostly boy’s toilets. All schools (n = 46, 94%) that have flush toilets is because they received sponsorship from non-government stakeholders that funded them in achieving piped water systems that permit the functionality of flush toilets. For the purposes of this study, hygiene was evaluate based on the items found in toilets and handwashing practices. The hygiene aspects of toilets included tissues, cleanness, and toilet seat. For handwashing practices we looked the number of washing basins, the colour of water, and having soaps to use. In the schools that did provide handwashing facilities, some of the toilets were broken, there was no water, or there was no drainage system in place to allow them to function. However, according to the school act, the handwash basins should be inside the facilities. A total of (n = 7, 14%) of handwash basins were inside the toilets. Only (n = 2, 4%) of schools had handwashing facilities which were Jojo tanks with taps near toilets, which were outside of the toilet, with no soap provided. Additionally, (n = 40, 82%) of learners used drinking points for handwashing, which can possibly transmit microbes among them. The findings revealed that, in general, (n = 32, 64%) of school toilets were clean, while, in general, the girls’ toilets were cleaner than the boys’ toilets. In all the schools, the cleaning services were from the people who were involved in school nutrition. In conclusion, there were water sources available for access to water inside schools; however, the situation can be improved by increasing the number of water source points. Pit latrines were the main used toilets, which were in a majority of the schools, and did not have the necessary terms for hygiene such as handwashing basin, tissues, and others. The lack of the main aspect, i.e., access to water and sanitation items, results in an impact on hygiene to learners as they will fail to practice proper hygiene. However, improvement can still be made by keeping the boys’ toilets clean while increasing the number of handwashing basins inside the toilets, so that they do not use taps outside the toilets. Schools should work towards meeting the required number of handwashing basins to increase access to handwashing facilities. Full article

The increasing pressure on urban systems and buildings in South Africa caused by rapid urbanization and climate change necessitates innovative approaches, including Nature-based Solutions (NbSs), to address environmental and societal challenges. As such, this study aimed to determine the dynamic role of NbSs in shaping the sustainability of South Africa’s built environment. Using a quantitative approach, the data were collected via a questionnaire survey, which targeted built environment professionals. Data analysis involved reliability testing, confirmatory factor analysis, and Spearman rank order correlation. The survey showed that green roofs, rainwater harvesting, cool roofing and pavements, as well as living walls, have received above-average attention in the country, while agricultural byproducts from concrete construction, bioswales, rain gardens, and algae-based materials are yet to be explored in the delivery of green buildings and sustainable urban areas. Overall, deploying NbSs promises positive environmental, societal, and economic impacts. The findings emphasize the need for stronger policies and regulations that promote the adoption of underutilized NbSs within the South African built environment. Theoretically, this study contributes to the existing discourse on sustainable development in South Africa. As the nation grapples with diverse environmental and social issues, this study becomes timely, as it provides crucial insights into how NbSs can address some of these challenges. Full article

Taiwan experiences abundant rainfall, but faces significant water shortages, making rainwater harvesting (RWH) a potential alternative water source. Additionally, extreme rainfall events strain urban flood control systems, highlighting the need for integrated stormwater management. To address these challenges, Taiwan mandates stormwater detention (SWD) in new buildings. However, the current RWH and SWD systems are designed independently, with no combined design guidelines available. This study proposes three combined RWH and SWD systems, series, parallel, and enhanced parallel with a valve using a passive release mechanism. System performance was evaluated through short-term and long-term simulations. Short-term simulations were conducted to ensure the system’s compliance with the domestic flood control design standards. These simulations assessed the peak flow mitigation and lag times for 5-, 10-, and 25-year design storms under four scenarios. Long-term simulations used historical rainfall data to analyze the differences in the combined systems and operational plans for continuous rainfall events. Three performance indicators—volumetric reliability, the stormwater retention ratio, and the stormwater detention ratio—were employed to assess water supply and the stormwater detention performance. The short-term simulation results revealed that the system performance was sensitive to the initial conditions. The series and parallel systems performed well, while the enhanced parallel system outperformed the others under specific initial conditions and valve operations. In contrast, long-term simulations revealed that the series and parallel systems achieved higher stormwater retention and a more stable performance than the enhanced parallel system. Among the three systems, the parallel system offers reduced installation space, lower costs, and easier maintenance, making it the recommended option for Taiwan. This study provides valuable guidance for designing combined RWH and SWD systems. Full article

The rising demand for water and energy is driving the overuse of natural resources and contributing to environmental degradation. To address these challenges, the focus has shifted to low- and zero-emission technologies that utilize alternative sources of water and energy. Although such systems are commonly applied in residential, commercial, and industrial buildings, facilities along transportation routes generally depend on grid connections. This study aimed to enhance operational independence and reduce environmental impacts by modernizing the Rest Area Stobierna (RAS) along Poland’s S19 expressway, part of the Via Carpatia road. A comprehensive technical, economic, and environmental analysis was conducted using HOMER Pro software (3.18.3 PRO Edition) and a simulation model based on YAS operating principles. The proposed Hybrid Renewable Energy System (HRES) incorporates photovoltaic panels, battery storage, and a rainwater harvesting system (RWHS). Two configurations of the HRES were evaluated, a prosumer-based setup and a hybrid-island mode. Optimization results showed that the hybrid-island configuration was most effective, achieving a 61.6% share of renewable energy in the annual balance, a 7.1-year return on investment, a EUR 0.77 million reduction in Net Present Cost (NPC), and a 75,002 kg decrease in CO₂ emissions over the system’s 25-year lifecycle. This study highlights the potential of integrating renewable energy and water systems to improve sustainability, reduce operational costs, and enhance service quality in road infrastructure facilities, offering a replicable model for similar contexts. Full article

Due to its unique climate and geography, Taiwan experiences abundant rainfall but still faces significant water scarcity. As a result, rainwater harvesting systems (RWHSs) have been recognized as potential water resources within both water legal and green building policies. However, the effects of climate change—manifested in more frequent extreme rainfall events and uneven rainfall distribution—have heightened the risks of both droughts and floods. This underscores the need to retrofit existing RWHSs to function as stormwater management tools and water supply sources. In Taiwan, the use of simple and cost-effective passive release systems is particularly suitable for such retrofits. Four key considerations are central to designing passive release RWHSs: the type of discharge outlet, the size of the outlet, the location of the outlet, and the system’s operational strategy. This study analyzes three commonly used outlet types—namely, the orifice, short stub fitting, and drainage pipe. Their respective discharge flow formulas and design charts have been developed and compared. To determine the appropriate outlet size, design storms with 2-, 5-, and 10-year return periods in the Taipei area were utilized to examine three different representative buildings. Selected combinations of outlet diameters and five different outlet locations were assessed. Additionally, probably hazardous rainfall events between 2014 and 2023 were used to verify the results obtained from the design storm analysis. Based on these analyses, the short stub fitting outlet type with a 15 mm outlet diameter was selected and verified. For determining the suitable discharge outlet location, a three-step process is recommended. First, the average annual water supply reliability for different scenarios and outlet locations in each representative building is calculated. Using this information, the maximum allowable decline in water supply reliability and the corresponding outlet location can be identified for each scenario. Second, break-even points between average annual water supply and regulated stormwater release curves, as well as the corresponding outlet locations, are identified. Finally, incremental analyses of average annual water supply and regulated stormwater release curves are conducted to determine the suitable outlet location for each scenario and representative building. For the representative detached house (DH), scenario 2, which designates 50% of the tank’s volume as detention space (i.e., the discharge outlet located halfway up the tank), and scenario 3, which designates 75% (i.e., the discharge outlet at one-quarter of the tank height), are the most suitable options. For the four-story building (FSB), the outlet located at one-quarter of the tank’s height is suitable for both scenarios 2 and 3. For the eight-story building (ESB), scenario 2, with the outlet at one-quarter of the tank’s height, and scenario 3, with the outlet at the lowest point on the tank’s side, are preferred. The framework developed in this study provides drainage designers with a systematic method for determining the key parameters in passive-release RWHS design at the household scale. Full article

The environmental impacts and water savings of different configurations of non-potable domestic water use (toilet flushing and laundry), sourced from rainwater harvesting (RWH) and air-conditioning condensate water (ACWH), in multi-family buildings in Israel are examined. Two building types differing in specific roof areas, and three climatic sub-regions were modeled. RWH satisfied 23 and 46% of the water demand for toilet flushing and laundry in high-rise and low-rise buildings, respectively. Air conditioning is used almost daily during Israel’s hot and dry summers. Hence, the combined RWH-ACWH system saved 42 and 64% in high- and low-rise buildings, respectively. Displacing desalinated seawater, a significant water source in Israel, with alternative water sources lowered the environmental impacts with an increase in storage, up to a certain volume, beyond which impacts started rising. The same infrastructure is used during winter for RWH and for ACWH during summer; thus, combining the two exhibits significant water savings, with marginal extra costs while lowering the environmental impacts. Full article

This research is focused on the water usage patterns in two student residences—one for male students (Residence I) and the other for female students (Residence II). Surveys and measurements of flushing cisterns, taps, and shower flows were conducted to understand water use behaviors. Scenario 1 proposed replacing washbasin and kitchen taps and installing flow reducers in showers, while Scenario 2 combined Scenario 1 with a rainwater harvesting system for recharging flush cisterns. Showers were found to be the most water-consuming devices, accounting for 46% and 61.41% of water consumption in Residences I and II, respectively, followed by kitchen taps (31.51% in Residence I and 11.52% in Residence II). The flushing cistern consumption was 7.02% in Residence I and 13.22% in Residence II. The implementation of Scenario 1 anticipates a 13% reduction in total water consumption in Residence I and a 10% reduction in Residence II. The reduction in hot water consumption would result in a decrease in annual electricity consumption by 27.8% and 23.06% in Residence I and II, respectively. With the implementation of Scenario 2, the total potential water savings for Residence I could increase to 19.98%, and for Residence II, it could rise to 23.17%. The proposed measures aim to enhance water sustainability in these buildings and can be replicated elsewhere. Full article

Water, a fundamental and indispensable resource necessary for the survival of living beings, has become a pressing issue in numerous regions worldwide due to scarcity. Urban areas, where the majority of the global population resides, witness a substantial consumption of blue water, particularly in commercial buildings. This study investigates the potential for enhancing water efficiency within an ongoing high-rise office building construction situated in a tropical climate. The investigation utilizes the green building guidelines of leadership in energy and environmental design (LEED) through a case-study-based research approach. Strategies included using efficient plumbing fixtures (such as high air–water ratio fixtures and dual-flush toilets), the selection of native plants, implementing a suitable irrigation system, introducing a rainwater harvesting system (RWHS) and improving the mechanical ventilation and air conditioning (MVAC) system. The results showed a 55% reduction in water use from efficient fixtures, a 93% reduction in landscaping water needs and a 73% overall water efficiency with a RWHS from the baseline design. Additionally, efficient cooling towers and the redirection of condensed water into the cooling tower make-up water tank improved the overall water efficiency to 38%, accounting for the water requirements of the MVAC system. The findings of this study can contribute to more sustainable and water-efficient urban development, particularly in regions facing water scarcity challenges. The significance of these findings lies in their potential to establish industry standards and inform policymakers in the building sector. They offer valuable insights for implementing effective strategies aimed at reducing blue water consumption across different building types. Full article

This study aimed to evaluate the financial feasibility of rainwater harvesting and greywater reuse in a multifamily building located in Florianópolis, Brazil. A building, consisting of two blocks with 60 flats each, was chosen to obtain data about the number of residents, building characteristics, potable water consumption, and rainwater and greywater demands (obtained by means of questionnaires and water measurements). The financial feasibility analyses considered rainwater and greywater systems separately and together. The impact on the urban stormwater drainage system was evaluated through the reduction of stormwater runoff. The energy consumption in the operational phase of each system was estimated through the amount of energy consumed by the motor pumps to supply one cubic meter of water. The potential for potable water savings through the use of rainwater—that supplies water for washing machines—was approximately 6.9%. The potential for potable water savings through the use of greywater—that supplies water to toilets—was approximately 5.7%. Both systems were feasible. The payback period for rainwater harvesting systems ranged from 57 to 76 months. For greywater systems, the payback period ranged from 127 to 159 months. When considering both systems working together, the payback period ranged from 89 to 132 months. The rainwater harvesting system can reduce 11.8% the stormwater volume destined to the urban stormwater drainage system in relation to the current contribution volume. Energy consumption was approximately 0.56 kWh/m³ of treated water for the rainwater harvesting system and 0.89 kWh/m³ of treated water for the greywater system. Rainwater and greywater were considered economically feasible, especially for higher inflation scenarios. Furthermore, such systems are interesting alternatives in terms of impacts considering urban drainage and energy consumption. Full article

Large industrial units generally consume considerable volumes of water for use by workers and sometimes in the manufacturing process, but on the other hand, they generally have large coverage areas that facilitate and enable the capture of large quantities of rainwater. Rainwater harvesting systems (RWHSs) are an alternative water supply with high potential for significant water and economic savings in buildings of this type, also with benefits for water resource sustainability. This paper presents a case study that refers to the design and economic viability determination of an RWHS to be installed in the industrial building of Continental Advanced Antenna Portugal, using an innovative tool called SAPRA—a rainwater harvesting and greywater reuse system in buildings. The main goal was to understand water consumption patterns in social areas (common to most of the industrial typologies) and determine whether RWHSs are feasible in such uses (discarding the production chain). The case study allowed for verification that the assumptions regarding the calculation period design flow significantly interfere with the design flow and the storage capacity. The analysis of the 10-year period yields the most realistic results, and can be framed, if necessary, within the range provided by the analysis of the driest and wettest years. The investment costs should between EUR 90 and 95 million, with annual savings of EUR 7 to 12 million, respectively. The expected payback period is between 7 and 11 years, which is quite feasible and very relevant. This may be an excellent example of how, even within the industries that do not need water for production, this may save significant volumes of water, contributing to the efficient use of this valuable resource. Full article

This study aims to analyse the technical viability and economic feasibility of rainwater-harvesting systems for single- and multifamily residential buildings in the city of Florianópolis, Brazil. Simulations were conducted for representative buildings in the city under different water-usage scenarios and system designs, in a total of 36 simulation scenarios. An economic analysis was performed for four scenarios over a twenty-year period. Both initial and operational costs were considered, and the net present value, internal rate of return, and payback were used as feasibility indicators. For houses, between 60.1% and 74.8% of the cases were economically feasible, achieving a discounted payback period ranging from 6.2 to 8.6 years. For flats, between 57.8% and 64.2% of the cases were economically feasible, achieving a discounted payback period ranging from 4.8 to 5.6 years. As the water tariff in the city underwent changes recently, the former and current tariff formats were compared. The current tariff format provides more economic benefits for saving potable water, and leads to a higher net present value and a shorter discounted payback period. This research stands out from previous studies as it examines a new scenario in the use of rainwater-harvesting systems. Full article

Sustainable rainwater management may counteract the effects of climate change and significantly improve the distorted water balance in urbanized catchments. However, despite the hydrologic advantages of rainwater management, acceptance and willingness-to-pay in the local society are required. This paper presents an assessment of the financial aspects, i.e., the cost-efficiency and economic feasibility, of various designs of rainwater management for a small-scale urban housing community in Lublin, Poland. The research was performed for a housing community covering approx. 1.38 ha and five multi-family residential buildings. The proposed designs covered rainwater harvesting systems, supported with extensive green roofs, with rainwater retained in underground or above-ground reservoirs, used with variable demand for watering the green areas and for underground parking lot flushing. For each designed variant, the investment as well as operation and maintenance costs were estimated. The assessment of the cost-efficiency and profitability of the proposed rainwater management systems was based on three indicators: Dynamic Generation Costs, Payback Period and Benefits–Costs Ratio. The performed calculations showed that only two designs, utilizing above-ground rainwater reservoirs, could be assessed as economically profitable. Thus, local communities may be unable to financially sustain investments in sustainable rainwater management, so it seems that financial support is required. Full article