Rooftop Rainwater Harvesting Systems Research Articles

Health Burden of the Consumption of Rooftop Rainwater Harvesting Systems in Buea Sub–Division, Cameroon

Health Burden of the Consumption of Rooftop Rainwater Harvesting Systems in Buea Sub–Division, Cameroon

Rainwater Harvesting System Analysis for Semi-Arid Climate: A Daily Linear Programming Model

Rainwater harvesting has proven to be an alternative water supply scheme for sustainable water management of regions with limited water resources. In this paper, a linear programming (LP) model with daily time steps, which minimizes a rooftop rainwater harvesting system (RWHS) cost, is developed and used to calculate the optimum RWH tank size. The developed LP model is applied to the semi-arid Northern Cyprus in the Eastern Mediterranean. The analysis is carried out for 33 sites which receive average annual rainfall ranging from 292 mm to 548 mm to evaluate the spatial effect of rainfall characteristic and the water cost on the financial feasibility and performance of the RWHS. At 29 out of 33 sites, RWHS investments are found to be financially feasible with discounted payback periods ranging from 12 to 28 years. The optimum RWH tank sizes are determined to be between 2 m3 and 6 m3 resulting in up to 20 % reliability with more than 50 m3 of average annual water savings per house. It is observed that the cost of water is a critical factor that affects the financial feasibility and water savings of a RWHS, especially in regions with limited rainfall. The comparison of the developed daily LP model with an LP model with monthly time steps demonstrates that the financial feasibility and the optimum tank size can only be assessed realistically when daily time steps are used. Finally, the sensitivity analysis shows that the discounted payback period is highly sensitive to the collector area.

Estimation of Roof Top Rain Water Harvesting Potential: A Proposed Solution to Water Scarcity in Shrigonda Town, Maharashtra, India

The burning issue in cities will be water scarcity in the coming years. The world population in cities has increased from 29.6 percent to 56.2 percent and is predicted to reach 68.4 percent by 2050. Therefore, this study has attempted to find a solution to tackle the urban water scarcity issue. Recently, rainwater harvesting has emerged as a sustainable and effective system for water conservation in urban areas. Hence, the ward-wise rooftop area was calculated and the rooftop rainwater harvesting potential was estimated by applying the Gould & Nissen, formula for Shrigonda Town. The result reveals that the total water demand in the water stress period was 41,34,41,010 litres while the total rainwater harvesting potential was 39,07,42,128 litres, which means about 94.51 % of the total demand will be met after the rooftop rainwater harvesting system is installed. The study concludes that rooftop rainwater harvesting is considered a sustainable and best alternative tool to tackle urban water scarcity.

Contribution of rooftop rainwater harvesting to climate adaptation in the city of Hannover: Water quality and health issues of rainwater storage in cisterns and ponds

Rooftop rainwater harvesting systems and blue-green infrastructure are becoming important resilience alternatives for urban climate adaptation. This study sheds light on the largely unreported physicochemical and microbiological quality of private roof-harvested rainwater (RHRW). We aimed to identify the physicochemical and microbiological characteristics of RHRW, explore potential correlations between them and assess probable health risks associated with recreational interactions of children with the water. RHRW was collected from cisterns and ponds located in an inner courtyard in Hanover, Germany. Physicochemical parameters were measured on site and samples were collected once a month in two campaigns in 2020 and 2021. Escherichia coli concentrations ranged from 1 × 10° to 24.1 × 102 MPN/100 mL, Enterococci from 1 × 10° to 19.7 × 102 MPN/100 mL, Salmonella from 1 × 102 to 39 × 103 CFU/100 mL and Pseudomonas aeruginosa from 1 × 10° to 3 × 103 MPN/100 mL. Correlation analysis indicated potential relationships between bacteria, oxygen, and water temperature. The results of the health risk assessment indicated a potential risk of gastrointestinal illnesses due to exposure to Enterococci and Salmonella spp. present in the cisterns and ponds, highlighting the need for appropriate regulations and guidelines for RHRW aimed for non-potable uses. Blue-green infrastructure, when effectively managed and maintained, can offer benefits both by enhancing urban climate resilience and promoting citizens well-being.

Rooftop Rainwater Harvesting System at MPCOE Campus

Rooftop Rainwater Harvesting System at MPCOE Campus

Unmanned aerial vehicles for planning rooftop rainwater harvesting systems: a case study from Gurgaon, India

Abstract Rooftop rainwater harvesting systems (RRWHS) effectively provide water access by storing precipitated water. The amount of water harvestable using these systems is proportional to the availability of rooftop areas in the region. The use of satellite imagery has gained traction in recent times considering the challenges in conducting a manual survey to determine the rooftop area. However, the limitations on spatial resolution impaired stakeholders from conducting similar assessments in areas with small residential units. In this regard, the use of unmanned aerial vehicles (UAVs) providing high-resolution spatial imagery for the delineation of rooftops of all scales has become popular. The present study is an attempt to utilize UAV-generated orthomosaics to estimate the harvestable quantity of rainwater for setting up an RRWHS. A study area in the Gurgaon district, India, is selected, and the steps involved in estimating the quantity of water harvestable using UAVs are demonstrated. In addition to these computations, a suitable site for constructing the storage unit is identified with the aid of a weighted overlay technique implemented using a Geographic Information System. The results from the study show that nearly 11,229 m3 of water can be harvested per year in the study site using the RRWHS.

Study on Potential and Practices of Rooftop Rainwater Harvesting System in Oxford College of Engineering and Management

The objective of this study was to evaluate the possibility of promoting rooftop rainwater harvesting to address future water scarcity in the Oxford College of Engineering and Management Nawalparasi district. AutoCAD software drew accepted plans and maps; manual measurement was done with measuring tape since some parts were missing.
 The results show that the linear forecast 1558.139, 1581.57mm,1548.63mm, 1598.14mm and 1570.64mm. The volume of water is 5135.54, 5028.16, 5188.94, 5099.68 respectively. It also shows the calculation of water demand which is 5,820,000 liters per year, and the water harvested is 5188946.58 liters per year. Finally, with this ratio, we realized we could fulfil 89.15% of water demand through water harvesting. The time series relevant results indicated that the A.R.I.M.A. model of forecasting rainfall was based on (0.1.0), signifying the R Square value is .631 and the p-value is insignificant (p > 250), which is better for this forecasting model.

The impact of the regularization on the economic analysis of rooftop rainwater harvesting system

Abstract In this study, the economic feasibility of rooftop rainwater harvesting of residential and public/commercial buildings for all 81 provinces of Türkiye is assessed. The Rippl method (RM) is used for optimal storage tank estimation. The net present value (NPV) and the discounted payback period (DPP) are used for economic analysis. Two scenarios were assessed using RM for (I) residential buildings and (II) public buildings. Optimal storage tanks for scenarios I and II were estimated by the selection of minimum roof areas to supply the demand for toilet flushing water for above 90% volumetric reliability. ArcGIS 10.2 was used to illustrate nationwide results of (1) roof areas and storage tank volumes, and (2) the economic analysis. The average DPP of rainwater harvesting system is 36 years for residential buildings and 23 years for public buildings. Based on NPV analysis, 17 out of 81 provinces are economically feasible for residential buildings. The feasibility status in public buildings is 43 economically feasible and 38 infeasible. More savings in public buildings can be obtained in a relatively shorter DPP. Furthermore, regularization is more effective in public buildings than residential buildings.

Study on Potential and Practices of Rooftop Rainwater Harvesting System in Oxford College of Engineering and Management

Study on Potential and Practices of Rooftop Rainwater Harvesting System in Oxford College of Engineering and Management

Assessing the Rainfall Water Harvesting Potential Using Geographical Information Systems (GIS)

Water scarcity is a major issue for developing countries due to the continuous increase in population every year, the major environmental challenges faced by developing countries such as Pakistan being the scarcity of water. One proposed solution to meet the requirements is to conserve water from rainfall. The process consists of the collection, storage, and use of rainwater. The rooftop rainwater harvesting systems (RWH) and rainfall harvesting system for artificially recharged water by recharge wells have received increased attention in the recent past as an efficient means of water conservation. In this study, both the systems have been analyzed for the University of Engineering and Technology Taxila (UET Taxila), Pakistan. The objective of this study is to propose a system to harvest water from the rooftops of all of the buildings on the campus and also to propose the most optimum locations of recharge wells for the artificial recharge of groundwater development. Numerous field visits were conducted after every rainfall over the past few months to identify lower elevation areas, which were further validated by the results obtained by Arc GIS. The total area of catchments available for rainwater harvesting in UET Taxila and the amount of water that could be harvested or used for replenishing groundwater reserves were also assessed in the current study. The results show that the harvestable rooftop water per month is 59% of the currently available source for watering trees and plants, and the harvestable water by recharge wells is 761,400 ft3 per year.

Performance of rooftop rainwater harvesting system as a source of drinking water

Rainwater Harvesting Systems (RWHSs) are increasingly being used as an alternative or supplementary source of water to curb the water supply deficit in the Kathmandu valley. The harvested rainwater is primarily used for non-potable purposes like flushing toilets and irrigation, but the knowledge on the use of rainwater for potable purpose is remarkably sparse. This study assesses the suitability of rainwater in terms of quantity and quality in a public school that adopts Rooftop RWHS as the source of drinking water. In this study, we observed that the volume of rainwater being harvested is sufficient to address the current demand of drinking water, with a mean rainfall of 1664 mm on a catchment area of 372 m2. Storage capacity needs to be expanded if the demand increases. Physico-chemical and microbial analyses of water samples (before and after a series of treatments) were carried out for the winter, monsoon, and post-monsoon seasons. The values of physico-chemical parameters of the water samples, in all the seasons, were well within both the National Drinking Water Quality Standards (NDWQS, 2005) and the World Health Organisation (WHO, 2017) guidelines for drinking water, while fecal coliforms were detected in the storage tank, but were absent in tap water after the treatments. Based on the findings, we suggest that the harvested rainwater could be used for drinking purposes if properly treated. RWHS use at the institutional level, like in schools, on the one hand, curbs the increasing demand for water in water-deficit locations like Kathmandu, and on the other, encourages the adoption of such sustainable technologies for the water supply.

Financial Potential Analysis of Rooftop Rainwater Harvesting System in Different Regions of China

Financial Potential Analysis of Rooftop Rainwater Harvesting System in Different Regions of China

An assessment of technical feasibility in the implementation of rooftop rainwater harvesting system in urban residential areas of Pakistan

An assessment of technical feasibility in the implementation of rooftop rainwater harvesting system in urban residential areas of Pakistan

An assessment of technical feasibility in the implementation of rooftop rainwater harvesting system in urban residential areas of Pakistan

An assessment of technical feasibility in the implementation of rooftop rainwater harvesting system in urban residential areas of Pakistan

Simulation of Rainwater Harvesting Potential to Satisfy Domestic Water Demand Based on Observed Precipitation Data in Jakarta

Jakarta as the most populous urban center of Indonesia has a major problem related to clean water availability for the domestic needs of its residents, who mostly depend on the extraction of groundwater. The rooftop rainwater harvesting (RRWH) system is a solution to reduce the use of groundwater to satisfy domestic water needs. This study used demographic data and precipitation observation data from the rain gauge network in Jakarta to simulate the water supply from rainwater harvesting from 2010 to 2019 in each municipality. Three simulations were carried out to calculate the percentage of domestic water demand (DS) satisfied by RRWH based on the proportion of residential areas installed with RRWH (RA). The results showed that an RA value of 0.2 produced the lowest DS (approximately 11% to 18.7%), while an RA value of 0.3 produced a higher DS (approximately 16.3% to 28%). An RA value of 0.4 resulted in a DS of around 21.8% to 37.4%. Overall, the RRWH system could provide up to 30% of domestic water demand on average, with South Jakarta having the highest fulfillment of water needs with an average of 28% based on the three simulations, while Central Jakarta had the lowest with 16.4%.

Rainwater Harvesting as an Alternative Water Supply in the Future of Bansal Institute of Engineering and Technology

Water scarcity is a major problem in many developing areas like Lucknow. Depending on precipitation intensity rainwater constitutes a major source of drinking water. In 2018 the annual rainfall measured in Lucknow (U.P.) was 1020 millimeters and in 2017 it was around 1127 millimeters. Which shows a rapidly decreased of rainwater fall. To avoid water crisis in the future we proposed an outcome solution for it. To established a rooftop rainwater harvesting system in Bansal institute of engineering and technology. It is an also solution for upcoming future generation. It is one step ahead to sustainable development. In times of heavy rains-when the full months rainfall on a single day, rainwater reuse systems help to reduce stress in rainfall infrastructure. Instead of rainwater going to galleries and overloading streams and rivers. It is kept in the water tanks of reuse systems. Hence adoption of different water conservation techniques at individual, institute and community level has become imperative to cater to the needs. This initiative can increase the water supply for construction work, gardening and also will help in artificial recharge of ground water thus enriching both the surface and the ground water resources. It was observed from the analysis that implementation of RWH system in Bansal institute of engineering and technology Lucknow can resolve the water scarcity problems during non-monsoon season by storing a huge quantity of water in a year in the college campus.

Productive Use of Natural Resources for Promotion of Horticultural Crop Production through Rooftop Rainwater Harvesting in Rain-Fed Hilly Areas of Punjab

Rainfall variability often results in low crop and fruit productivity in rain-fed hilly areas. Rooftop Rainwater Harvesting (RTWH) Technology can play a promising role in achieving agricultural production potential in these areas. Its adoption makes the supply of water sustainable for vegetables, fruit, and crop farming as well as domestic use. According to key informants, RTWH is being adopted in the study area on technical lines since the early 1990s. However, the availability of literature about economic aspects of the technology in the context of Pakistan is quite limited. This study is an effort to document the economic aspects of the technology including cost structure, potential benefits, net returns, and returns on investment. Thus, the study is based on a purposively selected sample of thirty farmers from Kotli Sattian and Murree tehsils of Rawalpindi district having operational RTWH systems installed at farms. The data have been analyzed for descriptive statistics and financial evaluation. Moreover, technical discussions with key informants and a detailed review of literature have also been made to substantiate the findings of the study. In the study area, farming families have diversified income sources with a considerably low share of agriculture in family income (19.5%). The mean command area of the RTWH systems at sample farms was 0.33 acres, which is allocated to different vegetables, and mainly to guava & citrus orchards. Benefit-cost ratios of vegetables and fruit farming through RTWH is 1.16, with returns on investment of 15 %, and a rate of return to labour of 0.95 in the first year of installation. Thus, technology is economically viable in the study area. Moreover, the financial gains of RTWH can be improved by enhancing storage capacity and increasing the command area.

Sustainable water resources through harvesting rainwater and the effectiveness of a low-cost water treatment

Increases in world population and climate change are some of the pressures affecting water resources for current and future water availability. The variability in water availability can reduce agricultural yields, food supplies and potentially leads to malnutrition and spread of diseases in water-poor countries. Even some water-rich countries can experience prolonged periods of dry weather, causing a drop in water reservoirs levels, forcing more restricted water resources management. Rainwater harvesting is one key option in adapting to water shortage and future demands that may alleviate the pressure on existing water resources. This work evaluates a roof top rainwater harvesting system (RWHS) installed as part of a decentralised wastewater treatment system designed to enable a circular economy by providing a more reliable water supply system in a remote public school in rural India. The effectiveness of the RWHS in reducing the pressure on a groundwater supply was assessed along with the physical, chemical and microbial characteristics of the stored rainwater over time. Further, the application of a low-cost primary treatment to make the harvested water safe to use for multiple purposes was investigated. The results revealed that the harvested water was of acceptable quality at the start of collection, however, microbial abundance increased when the rainwater was stored for a long time without treatment. Thus, a chlorine dosing regimen for the RWHS was designed based on laboratory and field experiments. The results also demonstrated that the low-cost chlorination process was effective in the field in reducing microbial abundance in the stored water for more than 30 days. However, as the residual chlorine level was reduced with time to <0.2 mg/l in the storage vessel, the microbial abundance increased, albeit to a much lower level that meets the Indian bathing water standards. The results provide evidence that installed RWHS has reduced the pressure on existing water supply at the school by up to 25% of the water that used for washing and flushing with no treatment, and with regular chlorination, greater savings and multiple uses of the stored rainwater can be achieved.

An assessment of adoption of rainwater harvesting system in residential buildings in Lahore, Pakistan

ABSTRACT Mounting water demand due to population growth and rapid urbanization, increasing water usage and associated water wastages make Lahore vulnerable in the context of changing climatic conditions. Lahore Development Authority (LDA), the principle planning agency in the city, introduced rainwater harvesting (RWH) system for residential buildings through clause 5.6.6 of building and zoning regulations 2014. This study explores the application of this regulation and documents associated dynamics. Findings established that a little proportion of residential buildings had constructed rooftop RWH system and yet these were not being used for its purpose. Chi-square and Cramer’s V were used for understanding the factors that influenced behavior of the residents for adoption of RWH. Fittingly, the study discovered that factors that could affect peoples’ willingness to adopt RWH in future were mechanism for incentives and penalties, peoples’ understanding about potential benefits of RWH, and continuing regulatory requirement for RWH supported by adequate enforcement.

Optimal storage sizing for indoor arena rainwater harvesting: Hydraulic simulation and economic assessment

This study demonstrates a large roof (30,000 m2) rainwater harvesting (RWH) system in an indoor arena by considering three water demand scenarios (toilet flushing, irrigation and combined demand) via hydraulic and economic assessments. The water saving efficiency (WSE) of the RWH system for each scenario was estimated by a simulation model using historical daily rainfall data (1968–2018). Depending on the water demand, the WSE was found to be independent of tank size when the tank size exceeded 1000 m3. The results suggest that the WSE of the RWH system is highly influenced by water demand scenarios, and a storage capacity of 400–1000 m3 would be enough for the applications considered in this study. The economic analysis results further showed that depending on the water demand, the RWH system with a rainwater storage capacity of between 100 and 600 m3 was more economically beneficial due to its positive cost saving values. The results also showed that depending on the water scenarios, the unit water cost between 0.37 and 0.40 £/m3 was lower than the mains water cost (0.40 £/m3). As a result, the use of the RWH system with a tank between 400 and 600 m3 can be the most favourable range under the conditions considered in this study. Given the variations in water price, rainfall patterns and discount rates, the sensitivity analysis showed that water tariffs and discount rates play a significant role in reducing the unit water cost of the system, maintaining it lower than the mains water cost. A payback period analysis of the RWH system with a 600 m3 tank revealed that a 5% discount rate and a water price of 3 £/m3 would be enough to make the RWH system cost effective and that the capital cost could be returned within 10–11 years. This study highlights the need for preliminary sizing of a rainwater tank and an economic analysis of a large rooftop RWH system to maximise the benefits.