Use Of Rainwater Harvesting Systems Research Articles

The Impact of the Water Tariff on the Economic Feasibility of Rainwater Harvesting for Use in Residential Buildings

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.

Water consumption assessment and classification in industrial buildings - The case study of Continental Advanced Antenna, Vila Real, Portugal

Water abstraction for the industrial, domestic, and agricultural sectors increased from 0.67 trillion m3/year in the 1900s to 3.79 trillion m3/year in 2000, and it is expected to increase by 55 % in 2050 when the majority of the world's population will live in urban areas. Concerning the industrial sector, despite the efforts to a more sustainable use, water is still an essential and irreplaceable resource, and this situation tends to increase due to modern industrial installations that require large-scale and complex water distribution systems. Usually, industries consume a large volume of water, however due to more and severer regulations, it is necessary to propose strategies for the aid of water conservation.This article presents a methodology to analyse, classify and optimize water consumption in industrial installations, using a real case study located in Vila Real, Portugal. The daily water consumption per worker, the daily record of use of each type of device and the hourly usage pattern were analysed and a classification was achieved according to the ANQIP (National Association for Quality in Building Installations) calculator. The case study revealed a great opportunity of improvement in what concerns to water efficient use. Some measures to improve the efficiency of water use in the building were pointed out, such as the use of rainwater harvesting systems, the use of aerators and replacements of taps and faucets when possible.The methodology is expeditious and user-friendly, and easy to replicate in similar cases, however it reveals some difficulties (especially in the data collection process that is made by inquiry, once it is always dependent on the respondent sensibility and willingness).

Rainwater harvesting systems: An urban flood risk mitigation measure in arid areas

Rainwater harvesting (RWH) systems have been developed to compensate for shortage in the water supply worldwide. Such systems are not very common in arid areas, particularly in the Gulf Region, due to the scarcity of rainfall and their reduced efficiency in covering water demand and reducing water consumption rates. In spite of this, RWH systems have the potential to reduce urban flood risks, particularly in densely populated areas. This study aimed to assess the potential use of RWH systems as urban flood mitigation measures in arid areas. Their utility in the retention of stormwater runoff and the reduction of water depth and extent were evaluated. The study was conducted in a residential area in Bahrain that experienced waterlogging after heavy rainfall events. The water demand patterns of housing units were analyzed, and the daily water balance for RWH tanks was evaluated. The effect of the implementation of RWH systems on the flood volume was evaluated with a two-dimensional hydrodynamic model. Flood simulations were conducted in several rainfall scenarios with different probabilities of occurrence. The results showed significant reductions in the flood depth and flood extent, but these effects were highly dependent on the rainfall intensity of the event. RWH systems are effective flood mitigation measures, particularly in urban arid regions short of proper stormwater control infrastructure, and they enhance the resilience of the built environment to urban floods.

Microbial Diversity in Rainwater with Correspondence to Particulate Matter and Environmental Factors

Microbial composition in rainwater has emerged as a trending research topic due to the increased use of rainwater harvesting systems (RWHS) worldwide. Studies have been conducted to analyze potentially pathogenic microorganisms in RWHS. However, the core focus in most papers has been on the rainwater collected in the storage tanks rather than the composition of microorganisms in fresh rainwater. Due to the microbial influence on air quality, this review dissects various studies that have identified the types of microorganisms in rainwater and their correspondence with atmospheric microbiota to understand airborne microbial movement and its effect. Current methods for rainwater analysis and technologies such as air mass models, that map the distribution of airborne microorganisms throughout the atmosphere, were evaluated to define factors that allow these organisms to move through different levels of the atmosphere. Additionally, the correlation between organisms found in rainwater and particulate matter was analyzed. This review discusses the importance of analyzing rainwater directly without limiting it to RWHS, like roof-harvested rainwater, in microbial source tracking. The paper also presents an overview of ecological contributions by microorganisms at a tropospheric level. Research gaps were noted in identification techniques, the type of microorganisms studied, and their ecological purposes, including paucity in viral detection. The uniqueness of this review is that potential new techniques were explored for prospective studies to improve and further analyze the microbial communities in rainwater. The more focus we give to microbial communities in fresh rainwater in the future, the easier it will be to predict the levels of pathogenicity and disease transmission related to airborne microbiota.

Health-risk assessment for roof-harvested rainwater via QMRA in Ikorodu area, Lagos, Nigeria

Abstract This paper presents a study to assess the roof-harvested rainwater (RHRW) in the Ikorodu area of Lagos state, Nigeria, and recommends guidance to minimise the health risk for its households. The types, design and use of rainwater harvesting systems have been evaluated in the study area to inspect the human risk of exposure to Escherichia coli (E. coli). To achieve these objectives, a detailed survey involving 125 households has been conducted which showed that 25% of them drink RHRW. Quantitative microbial risk assessment (QMRA) analysis has been used to quantify the risk of exposure to harmful E. coli from RHRW utilised as potable water, based on the ingestion of 2 L of rainwater per day per capita. Results have revealed that the maximum E. coli exposure risk from the consumption of RHRW, without application of any household water treatment technique (HWTTs) and with application of alum only, were 100 and 96 respectively, for the estimated number of infection risk per 10,000 exposed households per year. This estimation has been done based on 7% of E. coli as viable and harmful. Conclusively, it is necessary that a form of disinfectant be applied to the RHRW before use.

Improving Water Access and Health through Rainwater Harvesting: Perceptions of an Indigenous Community in Jalisco, Mexico

This article presents a mixed methods case study of an isolated indigenous community (the Wixaritari) in Jalisco state, Mexico, where the patterns of access to water have been changing due to Rainwater Harvesting Systems (RWHSs). The lack of water in this region is extremely precarious; women and children spend approximately one to three hours a day fetching water, and families live with less than 20 L per person/day. To better understand the relationship between water access and health derived from the use of RWHSs, we first analyzed epidemiological data (2014–2017) from cases of Acute Diarrheal Diseases (ADDs) and household water quality. Next, we surveyed households on water access after the introduction of RWHSs, including questions about perceptions of health problems associated with water. The results revealed that the introduction of RWHSs water access in this community has increased quantitatively and qualitatively and the incidence of ADDs has decreased significantly. However, the surveys and interviews indicate a disconnect between the incidence of ADDs and perceptions of health problems. We conclude that RWHSs can have tangible benefits, but they can be potentially undermined by perceptions of communities that have different understandings of the cause of disease.

A procedure to analyze the viability of rainwater harvesting systems in urban areas based on pre-defined diagrams

ABSTRACT Giving some specific precipitation regimes and technical design parameters, urban Rainwater Harvesting Systems (RWHS) may represent an alternative source to drinking water supply system promoting its conservation and rational use. The use of RWHS requires the definition of generic and simplified method for sizing RWHS accumulation tanks, which is has being considered the most expensive component of the system. Additionally, several methods have being used to define reservoir volumes leading to a wide variety of final reservoir volumes many of them over estimated. The main objective of this article is to present a new methodology to define RWHS reservoir volumes considering technical and economic viabilities of the systems. The proposed methodology was incorporated into a Decision Support System (DSS), named SARA. The method provides an alternative way to define smaller RWHS reservoir volumes once it accepts lower levels of reliabilities giving that the RWHS is considered a complimentary system, better suited for urban areas. RWHS design diagrams are built as a result of the methodology in an attempt to offer a tool to initial and rapid design of reservoir volumes for RWSH. The method was applied to different urban areas in Brazil.

Public Acceptance and Preference Towards Rainwater Harvesting in Klang Valley, Malaysia

This study explored the public acceptance and preference towards rainwater harvesting (RWH) in the area of Klang Valley. Self-administered questionnaires were used to obtain data from 109 respondents. An interview was also conducted on an individual representing a household with a RWH system. Respondents generally accepted that rainwater could be collected and reused for non-potable uses such as washing the porch and vehicles and watering the garden. While suggested WTP values of non-owners of the system fall below RM500, actual interview showed a homeowner spending a much higher amount for the system’s installation. Among the attributes of a RWH system preferred by respondents were affordability, safety and convenience. Added feature of a system preferred would be having a unit subsidized by the government. These findings may assist policymakers in finding ways to promote the development and use of RWH systems in the country.

Identification of Decisive Factors Determining the Continued Use of Rainwater Harvesting Systems for Agriculture Irrigation in Beijing

The success or failure of operating a rainwater harvesting system (RWH) depends on both technological and non-technological factors. The importance of non-technological factors in attaining sustainable RWH operation is rarely emphasized. This study aims to assess the contribution of non-technological factors through determining decisive factors involved in the use of RWHs for agriculture irrigation in Beijing. The RWHs for agriculture irrigation in Beijing are not operating as well as expected. If the decisive factors are identified to be non-technological, the significance of non-technological factors will be highlighted. Firstly, 10 impact factors comprising non-technological and technological factors are selected according to both a literature review and interviews with RWH managers. Following this, through an artificial data mining method, rough set analysis, the decisive factors are identified. Results show that two non-technological factors, “doubts about rainwater quality” and “the availability of groundwater” determine whether these systems will continue or cease RWH operation in Beijing. It is, thus, considered necessary to improve public confidence in and motivation on using rainwater for agriculture irrigation, as this is the main obstacle in the sustainable and successful operation of RWHs. Through a case study of RWHs in Beijing, the study verifies the importance of acknowledging non-technological factors to achieve sustainable water management and considers that such factors should receive more attention by decision makers and researchers.

Avaliação do potencial de redução do consumo de água potável por meio da implantação de sistemas de aproveitamento de água de chuva em edificações unifamiliares

In a scenario of relative water scarcity, it is advisable to implement public policies aiming at maintaining adequate potable water supply. A relevant alternative regarding water supply policies is the use of rainwater harvesting systems in residential buildings in order to meet the households non-potable water demands. This paper suggests a methodology to evaluate the potential for drinking water savings in urban area using rainwater for non-potable purposes in single-family dwellings. Hydraulic and financial assessments were performed, taking as case study Belo Horizonte, 2.4 million-inhabitant city that is the capital of the state of Minas Gerais. Results suggest that, in a scenario of widespread use of domestic rainwater harvesting systems, one can get the equivalent of two months of drinking water supply as drinking water annual savings. On the other hand, for the adopted scenario, results suggest economic feasibility of the systems, although with a high payback and internal rate of return very close to the attractive interest rates. These results suggest that the dissemination of these systems may require funding models and other economic tools to promote them for large scale use

Drinking water sources, availability, quality, access and utilization for goats in the Karak Governorate, Jordan.

Goat production is an important agricultural activity in Jordan. The country is one of the poorest countries in the world in terms of water scarcity. Provision of sufficient quantity of good quality drinking water is important for goats to maintain feed intake and production. This study aimed to evaluate the seasonal availability and quality of goats' drinking water sources, accessibility, and utilization in different zones in the Karak Governorate in southern Jordan. Data collection methods comprised interviews with purposively selected farmers and quality assessment of water sources. The provision of drinking water was considered as one of the major constraints for goat production, particularly during the dry season (DS). Long travel distances to the water sources, waiting time at watering points, and high fuel and labor costs were the key reasons associated with the problem. All the values of water quality (WQ) parameters were within acceptable limits of the guidelines for livestock drinking WQ with exception of iron, which showed slightly elevated concentration in one borehole source in the DS. These findings show that water shortage is an important problem leading to consequences for goat keepers. To alleviate the water shortage constraint and in view of the depleted groundwater sources, alternative water sources at reasonable distance have to be tapped and monitored for water quality and more efficient use of rainwater harvesting systems in the study area is recommended.

홍콩 주거건물에서 우수활용시스템의 생애주기비용분석

This paper investigates whether the use of Rainwater Harvesting Systems (RWHSs) to provide water for washing machines in Hong Kong residential buildings would be financially attractive. In such systems, rainwater is accumulated and reused for doing laundry, garden irrigation, flushing toilets, and even drinking. Thus, the analysis of RWHSs' financial feasibility is essential for construction projects. RainCycle is used to validate financial feasibility, considering particular circumstances and data relevant to the Hong Kong context. A range of different scenarios by adjusting three factors are evaluated: catchment area, water demand, and discount rate. It is suggested that would be a suitable catchment area in a typical Hong Kong residential building and it is demonstrated how water demand and discount rate influence the financial performance of RWHSs. In particular, the financial performance of RWHSs is sensitive to discount rates. The results suggest that the RWH system would be worthwhile for buildings with a lower number of floors, but would barely achieve financial validation in Hong Kong's super high-rise residential buildings.

Paradigm shift: Holistic approach for water management in urban environments

Conventional water infrastructure in urban environments is based on the centralized approach. This approach consists of building pipe network that provides potable water to consumers and drainage network that transport wastewater and stormwater runoff away from population centers. However, as illustrated in this article, centralized water infrastructures are not sustainable over a long period of time for a variety of reasons. This article presents the concept of a holistic approach for sustainable water management that incorporates decentralized water infrastructures into water management system design in urban environments. Decentralized water infrastructures are small to medium-scale systems that use and/or reuse local sources of water such as captured rainwater, stormwater runoff and wastewater. The holistic approach considers these waters as a valuable resource not to be wasted but utilized. This article briefly introduces various types of decentralized water infrastructures appropriate for urban settings. This article focuses on the effectiveness of rooftop rainwater harvesting systems as a decentralized water infrastructure and as a critical component of developing a holistic and sustainable water infrastructure in urban environments. Despite widespread use of rainwater harvesting systems, limited information has been published on its effectiveness for sustainable management of water resources and urban water infrastructures. This article, discusses multi-dimensional benefits of rainwater harvesting systems for sustainable management of water resources and its role as a critical component of decentralized water infrastructures in urban environments.

Review and quantitative assessment of ex situ household rainwater harvesting systems in Ethiopia

Ex situ household rainwater harvesting (RWH) systems have been introduced at a large scale in Ethiopia to increase the water availability for smallholders through supplementary irrigation. The first objective of this paper is to review the performance of these systems in Ethiopia based on various assessment studies. The second objective is to provide quantitative biophysical and socio-economic analyses of ex situ household RWH systems contributing to the better understanding of their performance and the identification of options to improve their performance. Uptake of RWH systems by smallholders in Ethiopia is limited and the available information suggests that this is associated among others with poor planning and implementation, poorly functioning input and output markets and the lack of farmers’ skills to use these systems effectively. Our quantitative meta-analyses illustrate that water availability of three studied RWH systems is low in relation to crop water needs, particularly for maize. The variation in area that can be irrigated across years exposes users of RWH systems to considerable risks as the availability of irrigation water depends on prevailing rainfall conditions. The area that can be irrigated varies greatly depending on amount and distribution of rainfall, type of RWH system and crop type. The economics of onion (cash crop) are promising only for plastic lined RWH systems, but those for maize are unfavourable independent of the studied RWH systems. Associated labour requirements especially for water lifting and application are high and possibly constraining the sustainable use of RWH systems. The potential of ex situ household RWH systems to increase agricultural production and income is site-specific depending on biophysical, institutional and socio-economic conditions, and depends on household-specific conditions.

A comparative appraisal of the use of rainwater harvesting in single and multi-family buildings of the Metropolitan Area of Barcelona (Spain): social experience, drinking water savings and economic costs

Many urban areas suffer water scarcity but paradoxically, a local source of water such as rainwater is mostly treated as a risk rather than as a valuable resource. Scepticism regarding the use of rainwater harvesting technologies still prevails today, particularly in low precipitation areas. However, some regions such as the Metropolitan Area of Barcelona (MAB) have started to promote the use of rainwater through specific regulations and incentives. This paper aims to examine the use of rainwater harvesting in the two main types of buildings prevalent in the MAB by analysing users’ practices and perceptions, drinking water savings and economic costs. Despite low precipitation inputs and a high variability of precipitation, daily balances show that toilet flushing demand of a single family house can be practically met with a relatively small tank. Rooftop rainwater can also meet more than 60% of the landscape irrigation demand in both single and multi-family buildings. The main drawback is the long pay-back period that rainwater harvesting systems present today. Nevertheless, it is remarkable that in multi-family buildings residents usually take no notice of the costs associated with the system. In contrast, benefits for the whole society are usually much more appreciated. Users’ reactions and their level of satisfaction towards rainwater harvesting systems suggest that both regulations and subsidies are good strategies to advocate and expand rainwater harvesting technologies in residential areas. However, a multidirectional learning environment needs to be promoted to ensure a proper use of rainwater harvesting systems and risk minimisation.

Performance of rainwater harvesting systems in the southeastern United States

Recent severe droughts, concerns over the environmental impact of stormwater runoff and increased water demands have generated interest in rainwater harvesting systems in humid, well developed regions, such as the southeastern United States. In order to evaluate the use of rainwater harvesting systems in this region, a monitoring study was conducted at three rainwater cisterns in North Carolina, a computer model was developed to simulate system performance, and simulations were conducted for 208 l rain barrels and larger cisterns. Results of the monitoring study showed that the rainwater harvesting systems were underutilized, which was suspected to result from poor estimation of water usage and public perception of the harvested rainwater. The computer model simulated system performance by evaluating a water balance using historical rainfall data and anticipated usage. Simulation results showed that a rain barrel was frequently depleted when used to meet household irrigation demands and overflowed during most rainfall events. Simulations also illustrated the improved performance of large systems while providing an indication of diminishing returns for increased cistern capacity.