Rainwater Harvesting for Drinking Water Production: A Sustainable and Cost-Effective Solution in The Netherlands?

Dynamic marginal cost curves to support water resources management

Marginal cost curves (MCCs) are popular decision-support tools for assessing and ranking the cost-effectiveness of different options in environmental policy and management. However, conventional MCC approaches have been criticized for lack of transparency and disregard for complexity; not accounting for interaction effects between measures; ignoring ancillary benefits and costs; and not considering intertemporal dynamics. In this paper, we present an approach to address these challenges using a system dynamics (SD)-based model for producing dynamic MCCs. We describe the approach by applying it to evaluate efforts to address water scarcity in a hypothetical, but representative, Swedish city. Our results show that the approach effectively addresses all four documented limitations of conventional MCC methods. They also show that combining MCCs with behavior-over-time graphs and causal-loop diagrams can lead to new policy insights and support a more inclusive decision-making process.

Community-Scale Rural Drinking Water Supply Systems Based on Harvested Rainwater: A Case Study of Australia and Vietnam

Rainwater harvesting (RWH) systems can be used to produce drinking water in rural communities, particularly in developing countries that lack a clean drinking water supply. Most previous research has focused on the application of RWH systems for individual urban households. This paper develops a yield-after-spillage water balance model (WBM) which can calculate the reliability, annual drinking water production (ADWP) and benefit–cost ratio (BCR) of a community-scale RWH system for rural drinking water supply. We consider multiple scenarios regarding community aspects, including 150–1000 users, 70–4800 kL rainwater storage, 20–50 L/capita/day (LCD) drinking water usage levels, local rainfall regimes and economic parameters of Australia (developed country) and Vietnam (developing country). The WBM analysis shows a strong correlation between water demand and water supply with 90% system reliability, which allows both Australian and Vietnamese systems to achieve the similar capability of ADWP and economic values of the produced drinking water. However, the cost of the Vietnamese system is higher due to the requirement of larger rainwater storage due to larger household size and lower rainfall in the dry season, which reduces the BCR compared to the Australian systems. It is found that the RWH systems can be feasibly implemented at the water price of 0.01 AUD/L for all the Vietnamese scenarios and for some Australian scenarios with drinking water demand over 6 kL/day.

Anaerobes and methanogens dominate the microbial communities in water harvesting ponds used by Kenyan rural smallholder farmers

Many rural smallholder farmers in Kenya use water-harvesting ponds, to collect rainwater, as sustainable sources of water for domestic and agricultural purposes. There is currently limited information regarding the microbial ecology in these ponds. Here, we used High Throughput Sequencing (HTS) to characterize the microorganisms present (including potential pathogens and indicator species) alongside ion chromatography to measure water chemistry (anion and cation concentration). Fluoride and magnesium concentration were the strongest predictor variables of the microbial community. Obligately or facultatively anaerobic bacterial genera (e.g. Spirochaeta and Opitutus) were abundant within the bacterial community, whilst Woesearchaeota and methanogens dominated the archaeal community. This suggests the water in the ponds is hypoxic or anoxic, and if used for irrigation, may potentially impact crop yield and viability. In addition, the opportunistic pathogen non-tuberculous mycobacteria (NTM), Mycobacterium fortuitum was found, comprising >1% of the bacterial community, suggesting a potential human health risk. Here we suggest low-cost changes to pond management, to improve or ameliorate pond anoxia and remove pathogens to benefit the livelihoods and welfare of these farms. This study also shows the applicability of HTS to broadly screen the microbial communities, assess water quality, and identify potentially pathogenic groups.

Adsorptive removal of pollutants from water using magnesium ferrite nanoadsorbent: a promising future material for water purification

Nanoadsorbents having large specific surface area, high pore volume with tunable pore size, affordability and easy magnetic separation gained much popularity in recent time. Iron-based nanoadsorbents showed higher adsorption capacity for different pollutant removal from water among other periodic elements. Spinel ferrite nanomaterials among iron-bearing adsorbent class performed better than single iron oxide and hydroxides due to their large surface area, mesoporous pore, high pore volume and stability. This work aimed at focusing on water treatment using magnesium ferrite (MgFe₂O₄) nanomaterials. Synthesis routes, properties and pollutant adsorption were critically investigated to explore the performance of magnesium ferrite in water treatment. Structural and surface properties were greatly affected by the factors involved in different synthesis routes and iron and magnesium ratio. Complete removal of pollutants through adsorption was achieved using magnesium ferrite. Pollutant adsorption capacity of MgFe₂O₄ and its modified forms was found several folds higher than Fe₂O₃ and Fe₃O₄ nanomaterials. In addition, MgFe₂O₄ showed strong stability in water than other pure iron oxide and hydroxide. Modification with graphene oxide, activated carbon, biochar and silica was demonstrated to be beneficial for enhanced adsorption capacity. Complex formation was suggested as a dominant mechanism for pollutant adsorption. These nanomaterials could be a viable and competitive adsorbent for diverse pollutant removal from water.

A Rainwater Harvesting and Treatment System for Domestic Use and Human Consumption in Native Communities in Amazonas (NW Peru): Technical and Economic Validation

The inhabitants of Tunants and Yahuahua face water supply problems in terms of quantity and quality, leading to socio-environmental and health impacts in the areas. The objective of this research, therefore, is to determine the technical and economic feasibility of a proposal for a rainwater harvesting and treatment system for human consumption in the native communities. For the technical feasibility, monthly water demand per family was compared with the amount of water collected in the rainy and dry seasons. In addition, 16 physical, chemical, and microbiological parameters were evaluated at the inlet and outlet of the water system. The economic feasibility was determined by the initial investment and maintenance of the systems; with the benefits, we obtained the net present social value (NPSV), social internal rate of return (SIRR), and cost-effectiveness (CE). Technically, oxygenation and chlorination in the storage tanks allowed for water quality in physical, chemical, and microbiological aspects, according to the D.S. N° 031-2010-SA standard, in all cases. Finally, with an initial investment of S/2,600 and S/70.00 for annual maintenance of the system, it is possible to supply up to six people per family with an average daily consumption of 32.5 L per person. It is suggested that the system be used at scale in the context of native communities in north-eastern Peru.

IoT Based Smart Water Quality Monitoring: Recent Techniques, Trends and Challenges for Domestic Applications

Safe water is becoming a scarce resource, due to the combined effects of increased population, pollution, and climate changes. Water quality monitoring is thus paramount, especially for domestic water. Traditionally used laboratory-based testing approaches are manual, costly, time consuming, and lack real-time feedback. Recently developed systems utilizing wireless sensor network (WSN) technology have reported weaknesses in energy management, data security, and communication coverage. Due to the recent advances in Internet-of-Things (IoT) that can be applied in the development of more efficient, secure, and cheaper systems with real-time capabilities, we present here a survey aimed at summarizing the current state of the art regarding IoT based smart water quality monitoring systems (IoT-WQMS) especially dedicated for domestic applications. In brief, this study probes into common water-quality monitoring (WQM) parameters, their safe-limits for drinking water, related smart sensors, critical review, and ratification of contemporary IoT-WQMS via a proposed empirical metric, analysis, and discussion and, finally, design recommendations for an efficient system. No doubt, this study will benefit the developing field of smart homes, offices, and cities.

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.

The Impact of System Integration on System Costs of a Neighborhood Energy and Water System

The fossil-based energy system is transitioning towards a renewable energy system. One important aspect is the spatial and temporal mismatch between intermitted supply and continuous demand. To ensure a reliable and affordable energy system, we propose an integrated system approach that integrates electricity production, mobility, heating of buildings and water management with a major role for storage and conversion. The minimization of energy transport in such an integrated system indicates the need for local optimization. This study focuses on a comparison between different novel system designs for neighborhood energy and water systems with varying modes of system integration, including all-electric, power-to-heat and power-to-hydrogen. A simulation model is developed to determine the energy and water balance and carry out economic analysis to calculate the system costs of various scenarios. We show that system costs are the lowest in a scenario that combines a hydrogen boiler and heat pumps for household heating; or a power-to-X system that combines power-to-heat, seasonal heat storage, and power-to-hydrogen (2070 €/household/year). Scenarios with electricity as the main energy carrier have higher retrofitting costs for buildings (insulation + heat pump), which leads to higher system costs (2320–2370 €/household/year) than more integrated systems. We conclude that diversification in energy carriers can contribute to a smooth transition of existing residential areas.

Microbiological Health Risk Assessment of Water Conservation Strategies: A Case Study in Amsterdam

The aim of this study was to assess the health risks that may arise from the implementation of greywater reuse and rainwater harvesting for household use, especially for toilet flushing. In addition, the risk of cross connections between these systems and the drinking water system was considered. Quantitative microbial risk assessment (QMRA) is a method that uses mathematical modelling to estimate the risk of infection when exposure to pathogens happens and was used in this study to assess the health risks. The results showed that using rainwater without prior treatment for toilet flushing poses an annual infection risk from L. pneumophila at 0.64 per-person-per-year (pppy) which exceeds the Dutch standard of 10-4 pppy. The use of untreated greywater showed a risk that is below the standard. However, treatment is recommended due to the ability of P. aeruginosa to grow in the reuse system. Moreover, showering and drinking with cross-connected water has a high annual infection risk that exceeds the standard due to contact with Staphylococcus aureus and E. coli O157:H7. Several measures can be implemented to mitigate the risks such as treating the greywater and rainwater with a minimum of 5-log removal, closing the toilet lid while flushing, good design of greywater and rainwater collection systems, and rigorous plumbing installation procedures.

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.

Analysis of Alternatives for Sustainable Stormwater Management in Small Developments of Polish Urban Catchments

Sustainable stormwater management approaches in accordance with the EU Water Framework Directive (WFD) allow a source control to handle the quality and quantity of the runoff at local level or near the source. The most popular technologies applied in Europe are green roofs, porous pavements, retention basins and bioswales/raingardens. In this article, two of these solutions (retention tank with reuse, and rain garden, respectively), applied to single dwelling case studies in a suburban area in the Silesia Region (Poland), are illustrated and analyzed. The selected cases consider technical and economic aspects as the most important factors for decision on the selection of onsite stormwater management approach. Both systems have been operational for approximately two years. The retention tank proved a good solution, reducing stormwater overflows and allowing local water reuse for lawn irrigation; however, investment and maintenance costs in this case are relatively higher. The raingarden proved to work efficiently in this small scale implementation and implied much lower initial investment and costs. The economic sustainability of these interventions at single dwelling scale was analyzed, showing interesting returns, with outcome depending on the degree of possible water reuse (lower water bills) and availability of fiscal or fee incentives. Introduction of financial incentive schemes will encourage homeowners and developers to implement stormwater control solutions, allowing rapid amortization of investment costs with additional benefits to the community, such as reduced environmental impact of stormwater overflows and possible economies in the construction and management of stormwater systems.

The Quality of Stored Rainwater for Washing Purposes

The use of rainwater for washing clothes is determined by its amount, composition and quality of washing. Raw rainwater is soft and free of pollution. The collected rainwater already contains pollution present in the atmosphere and washed away from roofs and other surfaces. It can also change its quality when stored in tanks. Washing clothes does not require drinking quality water but just clean, safe water that guarantees effective removal of dirt from fabrics. The study determined the physicochemical and microbiological changes of rainwater characteristics during retention. Rainwater was collected in a standard underground tank for 30 days and water analyses were conducted every 10 days. The possibility of tap water replacement in the household with collected rainwater for ecological clothes washing has been assessed.

Solving the Manufacturing Cell Design Problem through an Autonomous Water Cycle Algorithm

Metaheuristics are multi-purpose problem solvers devoted to particularly tackle large instances of complex optimization problems. However, in spite of the relevance of metaheuristics in the optimization world, their proper design and implementation to reach optimal solutions is not a simple task. Metaheuristics require an initial parameter configuration, which is dramatically relevant for the efficient exploration and exploitation of the search space, and therefore to the effective finding of high-quality solutions. In this paper, the authors propose a variation of the water cycle inspired metaheuristic capable of automatically adjusting its parameter by using the autonomous search paradigm. The goal of our proposal is to explore and to exploit promising regions of the search space to rapidly converge to optimal solutions. To validate the proposal, we tested 160 instances of the manufacturing cell design problem, which is a relevant problem for the industry, whose objective is to minimize the number of movements and exchanges of parts between organizational elements called cells. As a result of the experimental analysis, the authors checked that the proposal performs similarly to the default approach, but without being specifically configured for solving the problem.

Public Water Supply and Sanitation Authorities for Strategic Sustainable Domestic Water Management. A Case of Iringa Region In Tanzania

Water supply is a mandatory service for the majority from respective legal public water utilities, and its sustainability reflects implementations of best management strategies at a local level. The objectives of this study were (i) to assess current approaches used in water quality and quantity management and (ii) propose a sustainable domestic water management strategy. This was achieved through secondary water data trends, on-site water quality assessments, visits of water supply and sanitation authorities, and assessment of their performances. It was observed that water supplied in rural-based authorities was quite different from that supplied in an urban setting as far as quality and quantity are concerned; urban-based supplies are more affordable to users than rural ones. A new strategy on water management is presented for sustainable water supply; it is based on controlling groundwater abstractions and preference of surface water in public water supplies. Rural water supply management must learn several practices realized in urban supplies for the betterment of services for the majority of the users.

The Challenges of Water Management and Governance in Cities

Combined impacts of sea-level rise, river flooding, increased frequency and magnitude of extreme rainfall, heatwaves, water scarcity, water pollution, ageing or lacking infrastructures for water, wastewater and solid waste in rapidly urbanising regions in the world call for improved water management and governance capacity in cities to accelerate the transition to water-wise cities. The sixteen contributions to this Special Issue create further awareness and present solutions on integrated approaches, advanced water management practices and water governance strategies. It is concluded that cities require a long-term strategy and a multilevel water governance approach. Research has shown how important it is to involve the civil society and private parties early on in this process to create success. Collaboration among cities and regions by sharing best practices for rapid implementation are crucial to cope with nearly all Sustainable Development Goals.