Decentralized Water Systems Research Articles

An Analysis of the Effectiveness of Two Rainwater Harvesting Systems Located in Central Eastern Europe

Decentralized water systems are perceived as solutions that not only save water, but also as a way to partially or completely become independent from centralized suppliers. Taking this into account, an analysis of the effectiveness of rainwater harvesting systems (RWHS) for toilet flushing in existing academic facilities located in Poland and in Slovakia was carried out. The tests took into account the different volumes of storage tanks collecting rainwater. On the basis of two financial ratios, namely Net Present Value and Discounted Payback Period, the profitability of these systems was also assessed. The research was extended by the sensitivity analysis, which allowed determination of the impact of changes in individual cost components on the financial effectiveness of the investments considered. The results obtained clearly showed that the implementation of RWHS in the dormitory in Rzeszów was unprofitable for all tank capacities tested, and the payback period significantly exceeded the period of 30 years accepted for the analysis. Completely different results were obtained for RWHS in a dormitory located in the city of Košice, for which the financial ratios NPV (Net Present Value) and DPP (Discounted Payback Period) were very favorable. It was also confirmed by the results of the sensitivity analysis. The use of rainwater for toilet flushing caused that it was possible to achieve water savings of an average of 29% and 18%, respectively, for facilities located in Slovakia and Poland. The results of the research have a practical aspect and can provide an indication for potential investors and managers of academic facilities, similar to those analyzed in the article. Taking into account that in many countries water and sewage rates are significantly higher than in Poland and Slovakia, the cost-effectiveness of using the analyzed installation options in these countries could be even higher.

Sustainable and Resilient Urban Water Systems: The Role of Decentralization and Planning

Urban water systems face multiple challenges related to future uncertainty and pressures to provide more sustainable and resilient modes of service delivery. Transitioning away from fully centralized water systems is seen as a primary solution to addressing these urban challenges and pressures. We first review the literature on advantages, potential risks, and impediments to change associated with decentralized water system. Our review suggests that adopting decentralized solutions may advance conditions of sustainability and resilience in urban water management. We then explore the potential to incorporate decentralized water systems into broader urban land use patterns that include underserved residential neighborhoods, mixed-use developments, and industrial districts.

Willingness to Pay for Improved Water Services in Mining Regions of Developing Economies: Case Study of a Coal Mining Project in Thar Coalfield, Pakistan

Local communities in mining regions are vulnerable to water scarcity risks caused by extensive mining and changing climate. To mitigate such risks, we adopt a non-market valuation of low income communities’ preferences for improved access to water services, as an effort to develop pro-poor policies that bring long-term water security and benefits to the local people. Using data collected from 268 households from the mining site in the Thar coalfield (Pakistan), we examine the household willingness to pay (WTP) for all major uses based on hypothetical policy scenarios. Results show that the mean WTP was estimated to be PKR 3921 (USD 38) for risk averting services (S1) and PKR 4927 (USD 48.13) for domestic pipelines and more decentralized water systems (S2) per month. We found that the mean WTP for S1 is 11.8% and for S2 is 16.6% more than the existing water-related expenditures of households. Age of household head, income level, project employment, livestock, farm income, and water quality are the significant factors influencing their WTP. These findings provide empirical evidence to policymakers and resource managers to implement cost-effective water management plans that provide multiple ecosystem service benefits, thereby potentially aiding pro-poor and sustainable economic growth in mining regions.

A coupled modeling framework for sustainable watershed management in transboundary river basins

Abstract. There is a growing recognition among water resource managers that sustainable watershed management needs to not only account for the diverse ways humans benefit from the environment, but also incorporate the impact of human actions on the natural system. Coupled natural–human system modeling through explicit modeling of both natural and human behavior can help reveal the reciprocal interactions and co-evolution of the natural and human systems. This study develops a spatially scalable, generalized agent-based modeling (ABM) framework consisting of a process-based semi-distributed hydrologic model (SWAT) and a decentralized water system model to simulate the impacts of water resource management decisions that affect the food–water–energy–environment (FWEE) nexus at a watershed scale. Agents within a river basin are geographically delineated based on both political and watershed boundaries and represent key stakeholders of ecosystem services. Agents decide about the priority across three primary water uses: food production, hydropower generation and ecosystem health within their geographical domains. Agents interact with the environment (streamflow) through the SWAT model and interact with other agents through a parameter representing willingness to cooperate. The innovative two-way coupling between the water system model and SWAT enables this framework to fully explore the feedback of human decisions on the environmental dynamics and vice versa. To support non-technical stakeholder interactions, a web-based user interface has been developed that allows for role-play and participatory modeling. The generalized ABM framework is also tested in two key transboundary river basins, the Mekong River basin in Southeast Asia and the Niger River basin in West Africa, where water uses for ecosystem health compete with growing human demands on food and energy resources. We present modeling results for crop production, energy generation and violation of eco-hydrological indicators at both the agent and basin-wide levels to shed light on holistic FWEE management policies in these two basins.

Evaluating the Life Cycle Environmental Benefits and Trade-Offs of Water Reuse Systems for Net-Zero Buildings

Aging water infrastructure and increased water scarcity have resulted in higher interest in water reuse and decentralization. Rating systems for high-performance buildings implicitly promote the use of building-scale, decentralized water supply and treatment technologies. It is important to recognize the potential benefits and trade-offs of decentralized and centralized water systems in the context of high-performance buildings. For this reason and to fill a gap in the current literature, we completed a life cycle assessment (LCA) of the decentralized water system of a high-performance, net-zero energy, net-zero water building (NZB) that received multiple green building certifications and compared the results with two modeled buildings (conventional and water efficient) using centralized water systems. We investigated the NZB's impacts over varying lifetimes, conducted a break-even analysis, and included Monte Carlo uncertainty analysis. The results show that, although the NZB performs better in most categories than the conventional building, the water efficient building generally outperforms the NZB. The lifetime of the NZB, septic tank aeration, and use of solar energy have been found to be important factors in the NZB's impacts. While these findings are specific to the case study building, location, and treatment technologies, the framework for comparison of water and wastewater impacts of various buildings can be applied during building design to aid decision making. As we design and operate high-performance buildings, the potential trade-offs of advanced decentralized water treatment systems should be considered.

Building commons to cope with chaotic urbanization? Performance and sustainability of decentralized water services in the outskirts of Kinshasa

With an estimated 10.6 million inhabitants in 2015 and an average 6.6% annual growth rate, Kinshasa ranks among the three largest cities in Africa and may well become the most populated. To cope with critically deficient water services, a local NGO supported by different donors has promoted decentralized water systems (DWS) that have spread in the city outskirts, based on a model with original features compared to other African experiences. Here, we intend to provide an empirically grounded and analytically sound inquiry into the relevance, efficiency and sustainability of these DWSs in the context of the megacity of Kinshasa. First, we analyze water provision data from the national water utility and compare these to the detailed operational results of the DWSs to estimate the magnitude and efficiency of this alternative mechanism. Second, the principles identified by Elinor Ostrom as being crucial for institutions to successfully manage commons provide us with a fruitful analytic framework to assess DWS performance and sustainability. We show that some of these criteria are broadly met, but the fulfillment of other criteria is still uncertain. We conclude with a balanced assessment of the efficiency and sustainability of this approach and identify the key challenges.

A systematic review and agenda for using alternative water sources for consumer markets in Australia

Water scarcity is a common phenomenon identified in many countries and Australia is no exception. Australia is the driest continent and has been prone to severe and prolonged drought conditions in recent years. Yet the quality of drinking water is taken for granted in Australia and existing evidence showcases a huge setback in the uptake of alternative sources of water by Australian consumer markets. In order to understand the existing situation and identify the barriers and opportunities associated to alternative sources of water, a systematic review of existing research in the area of alternative sources of water for consumer markets has been conducted. The importance of water as a precious resource to sustain human life and a review of relevant literature of alternative sources of water (mainly recycled and desalinated) and issues surrounding centralised and decentralised water systems are discussed. Results are reported from extant research upon public acceptance of consumer satisfaction, contextual factors, demographic variables and perceived benefits and costs associated with the intention to adopt, and the adoption and use of recycled and desalinated water. Our findings highlight the limitations of prior studies and outline the strategic importance of a much needed marketing-related 7Ps research framework for promoting the consumption and use of alternative water sources within the Australian consumer market. Similarly the discussion highlights the relative importance of investing in various marketing interventions in enhancing Australian consumer markets awareness, acceptance and uptake of alternative sources of water. The uptake of alternative sources of water amongst Australian consumer markets is envisaged to be enhanced through critical understanding of the various aspects associated to product, price, place, promotion, people, process and physical evidence. In sum, the present systematic review provides the most relevant issues surrounding the usage of alternative sources of water within the Australian consumer market; elicits the importance of public acceptance, consumer satisfaction, demographic variables, contextual factors apart from benefits and barriers to recycled water; and proposes a research framework that needs to be addressed by future research.

Risks and tensions in water industry innovation: understanding adoption of decentralised water systems from a socio-technical transitions perspective

Globally, centralised urban water systems are under pressure to respond to environmental and economic pressures. In Australia, high infrastructure costs and variable rainfall have prompted governments, end-users and property developers to begin investing in more decentralised systems that use alternative water sources (rainwater, stormwater and wastewater). This trend is based on a fit-for-purpose principle and is part of a global shift toward sustainable urban water management. These developments suggest that Australia's urban water sector may be in the early stages of transition and represent a multi-decadal shift from centralisation of water supply and sanitation to partial decentralisation based on local conditions. Much of the scholarship on decentralised systems focuses on drivers and barriers to adoption, which implies a static and mechanistic process of change, and overlooks the complex interplay between exogenous pressures, innovation, multiple actors and industry reform. This paper addresses this gap by analysing temporal processes of Australia's urban water sector, using a regionally based case study comprising an historical review and interview study that analyses the multi-level, -decadal and -actor developments at the nexus between water service provision and property development. The analysis revealed emerging tensions between incumbent water utilities, property developers and end-users, and an inherent conflict between neo-liberal and environmental policy agendas. Such tensions and conflicts are missing from urban water policy and research discourse.

Risk governance in the water sensitive city: Practitioner perspectives on ownership, management and trust

In the water sensitive city, a hybrid mix of centralised and decentralised water systems and sources will operate at a range of scales to provide sustainable fit-for-purpose water services that will safeguard environmental quality, intergenerational equity and landscape amenity. Governance of these systems is likely to differ from the traditional arrangement, involving multiple stakeholders who must work together to manage risk. Trust will be essential to effective governance. This study explored attitudes of Australian urban water practitioners towards ownership and management of different water systems that might comprise the water sensitive city, including who they would trust to manage the associated risk. Results support the status quo, in which risk management responsibilities lie with state and local government or corporatised water utilities. Although practitioners support ownership and management of lot-scale water systems by homeowners, they trust them only to manage the risks associated with rainwater tanks. These results can be interpreted as risk perceptions, which are influenced by trust and knowledge. Implementation of decentralised water systems should be accompanied by governance arrangements that include strategies to enhance trust between stakeholders and to facilitate the co-production of knowledge to inform shared decision-making.

Sustainable Water Systems for the City of Tomorrow—A Conceptual Framework

Urban water systems are an example of complex, dynamic human–environment coupled systems which exhibit emergent behaviors that transcend individual scientific disciplines. While previous siloed approaches to water services (i.e., water resources, drinking water, wastewater, and stormwater) have led to great improvements in public health protection, sustainable solutions for a growing global population facing increased resource constraints demand a paradigm shift based on holistic management to maximize the use and recovery of water, energy, nutrients, and materials. The objective of this review paper is to highlight the issues in traditional water systems including water demand and use, centralized configuration, sewer collection systems, characteristics of mixed wastewater, and to explore alternative solutions such as decentralized water systems, fit for purpose and water reuse, natural/green infrastructure, vacuum sewer collection systems, and nutrient/energy recovery. This review also emphasizes a system thinking approach for evaluating alternatives that should include sustainability indicators and metrics such as emergy to assess global system efficiency. An example paradigm shift design for urban water system is presented, not as the recommended solution for all environments, but to emphasize the framework of system-level analysis and the need to visualize water services as an organic whole. When water systems are designed to maximize the resources and optimum efficiency, they are more prevailing and sustainable than siloed management because a system is more than the sum of its parts.

The influence of coping appraisals on the adoption of decentralised water systems in Australia

In Australia, water scarcity has resulted in the need for re-evaluating demand management policies, as well as the identification of alternative water supplies. Specifically, water utilities have been focusing on increasing the adoption of household level decentralised water systems (DWS). While such engineering solutions may be effective, understanding the factors which influence adoption is crucial for widespread uptake. Protection Motivation (PM) theory was used to assess DWS adoption in a sample of 295 homeowners across South East Queensland, Australia. Results provided good support for the application of PM theory to understanding whether people cope adaptively to water shortage threats. The model’s hypothesised link between adaptive coping and behavioural intention was also supported, suggesting PM theory can be used to understand people’s intention to adopt DWS in the context of the drought. The predictive ability of the PM model improved significantly when demographic variables – age and perceived water – use were included.

Interactions between centralized and decentralized water systems in urban context: A review

This study presents a comprehensive review of the literature on implementation of various decentralized water systems along with centralized systems. The review highlights the benefits provided by these systems as well as various challenges posed associated with them. There are complex interactions involved within the water systems in an urban setting that are multidimensional and span over various aspects of water availability, quality, energy use, environmental, legal, economic, and social sectors. Although there are many economic, environmental, and social benefits associated with decentralized systems, there are some hidden challenges that are generally overlooked by planners and managers; these include the spatial integration of such systems, their energy intensity, social, economic, and environmental viability of these systems. Decisions to implement decentralized water systems require decision makers to consider economic, social, and environmental dimensions conjointly through an appropriate multicriteria decision analysis to select the hybrid water supply combination optimal for the given circumstances. The existing studies and tools are unable to address these factors using an integrated approach. So a holistic framework to evaluate and compare various water supply options in terms of energy use, social, economic, and environmental impacts is required to assess such systems in comprehensive manner. WIREs Water 2015, 2:623–634. doi: 10.1002/wat2.1099This article is categorized under: Engineering Water > Planning Water Engineering Water > Sustainable Engineering of Water

Decentralized Water Systems for Sustainable and Reliable Supply

The water utility industry is under enormous pressure to meet the challenges of increasing demands due to population growth and lifestyle changes, and depleting freshwater resources. Deteriorating supply infrastructure makes the task of meeting water demands even more challenging. The combination of source and supply challenges encouraged the consideration of sustainable and reliable alternatives for future water supply management. On-site greywater reuse is one such alternative that is becoming increasingly popular for its sustainable benefits such as ready availability, energy savings, reduced freshwater withdrawals and less effluent runoff. While the treatment technologies for making it economically viable are currently being investigated by other researchers, this paper investigates the improvement in supply reliability when traditional water supply systems are complemented by on-site greywater reuse. A robust computational model is developed for quantifying reliabilities of traditional and on-site greywater reuse systems for a given study area. The results revealed that there is up to 17% of improvement in supply reliability due to the on-site greywater reuse systems. A one-way sensitivity analysis conducted on the results indicated that the observed reliability improvement is sensitive to system age, pipeline roughness, treatment efficiency and allowable use of reclaimed water. Further research is needed to investigate the value of this reliability improvement by considering the life cycle cost and energy implications of on-site greywater reuse alternative.

Renegotiating urban water

Water infrastructure is essential for the functioning of modern cities. This paper analyses conventional models of water infrastructure provision and emerging alternatives in order to identify points of reform and resistance in the relationship between people, technology and water in cities. It begins with a review of recent academic contributions to understanding the relationships between people, technology and nature in cities through the analysis of urban infrastructure. The work of Andrew Feenberg, a critical philosopher of technology, is presented as the basis for analysing both the technical and discursive elements of infrastructure. Feenberg's concept of ‘the technical code’ is used to synthesise key insights from the analysis of urban infrastructure and technology, to devise a series of critical categories for comparing changes currently underway in urban water infrastructure provision. This ‘technical discourse of water infrastructure’ is used to analyse developments in desalination, wastewater reuse, decentralised non-potable supply, domestic water efficiency, water sensitive urban design and ecological sanitation. Planners, designers and policy makers concerned about sustainability should be wary of the technical inevitability of desalination, potable recycling and other systems which reinstate conventional codes of domination and control of nature and separation of public concern from technical rationality. Decentralised water systems embody assumptions about the limits to water resources, but can also be problematic as high users of energy and reinforcing a private right to water. Improving the efficiency of domestic water using technologies and appliances is unarguably important in achieving sustainability. Moving beyond water efficiency to open up discussions about water using practices and cultural norms holds greater potential for transforming water consumption. Water Sensitive Urban Design is widely championed by designers and planners as exemplifying a sustainable approach to urban nature, providing a useful foundation for moving beyond drainage into water supply and wastewater technology and discourse. Ecological sanitation is filling a basic necessity in developing cities and may be part of a longer term transition to sustainability in developed cities in the future. Eliminating water from sanitation and recovering resources from waste holds the potential to radically reorder relationships between bodies, urban spaces and nature. Relationships between cities, technologies and water are shifting. The extent to which this balance falls in favour of sustainability over coming decades will be determined by political discourse as well as technical innovation.

Basic Psychological Needs Influencing the Regularity of Domestic Rainwater Tank Maintenance

Inadequate and irregular maintenance of rainwater tanks can lead to health risks, affecting individual users (e.g. home owners and others who may use/consume the water) and the general public more indirectly, through the spread of water borne disease and potentially costly health impacts. This study examines the relationship between basic psychological needs (competence, autonomy, relatedness) and regularity of rainwater tank maintenance for urban non-potable use tanks. A mail out survey was sent to urban householders in South East Queensland, Australia, who lived in new detached dwellings with mandated rainwater tanks (N = 754). Multiple regression analysis found that competence, autonomy and relatedness accounted for a moderate-high amount of variance (24 %) in regular tank maintenance behaviour; competence was found to be the most dominant factor in explaining maintenance behaviour, indicating that people were more motivated to carry out maintenance if they perceived themselves as able to do the maintenance required. As decentralised water systems become more popular in urban areas, it is crucial that citizens maintain their alternative water infrastructure to minimise public health risks associated with water- and vector-borne illnesses. This research is crucial to understanding psychological drivers of tank maintenance, particularly among individuals who did not choose to adopt decentralised tank infrastructure (i.e. were mandated to install the infrastructure) and, therefore, may be unfamiliar and unmotivated to use or maintain their tanks for non-potable applications.

Adapting to Less Water: Household Willingness to Pay for Decentralised Water Systems in Urban Australia

In South East Queensland (SEQ), extended periods of drought and unprecedented population growth have resulted in a water strategy reliant on permanent water conservation measures. As a result, there has been increasing emphasis on the installation of decentralised water systems at the household level, in particular, rainwater tanks and greywater systems to ease the water shortage stress. Results from a survey of 590 households in SEQ reveal that willingness to pay (WTP) for rainwater tanks and greywater systems range from $800 to $7,400 and from $1,700 to $14,100, respectively. When compared to the actual market price, WTP is substantially lower and subsidies will be required to encourage adoption. Nonetheless, a subsidy of $500 can lead to 100 % uptake of greywater diversion devices. Hence, the policy implication is that not all devices are preferred and subsidising greywater diversion devices would lead to the highest level of uptake with the least amount of subsidy spending.

Assessing preferences regarding centralized and decentralized water infrastructure in post-earthquake Leogane, Haiti

BackgroundThough the benefits of centralized water systems (e.g. improved publichealth, environmental protection, streamlined operations, economy of scale, reliability) are well known, these systems are not always feasible or appropriate. In developing world settings there has been growing interest by infrastructure experts,researchers, and international lending institutions in decentralized means of improving access to drinking water. While decentralized water systems with independent components may be less vulnerable to systemic failures, hazards, and extreme environmental events, centralized water systems are often associated with a higher quality of life. This study investigates stakeholder preferences regarding water infrastructure issues in Leogane, Haiti (population ~300,000), a town situated at the epicenter of the January 2010 earthquake.MethodsThe methodology included a paper survey, semi-structured interviews, and a participatory workshop.ResultsWhile most of the study participants relied on decentralized water sources prior to the earthquake, a majority also expressed a preference for a centralized water system going forward. However, the study participants articulated an integrated vision for the future of local water management. Study participants indicated an interest in alternative decentralized solutions, for example featuring artesian wells with homewater treatment, and saw linkages between water supply decisions and local environmental protection, agriculture, and deforestation.ConclusionsThese results are discussed within the context of sustainable infrastructure reconstruction efforts in Haiti, specifically as an example of how local preferences can be integrated into the visioning of infrastructure design.

Wastewater reclamation for various non-potable supplies and water quality control in a minimum-emission hydrologic cycle

In this study, we implemented an isolated decentralized water system with minimized wastewater discharge and maximized water reuse in water-deficient region. Dual quality wastewater reclamation and reuse system with parallel conventional treatment unit and advanced MBR treatment unit was built in which the reclaimed water with normal quality and high quality was produced, respectively. Based on maximum collection of the recollectable discharged water, the minimum-emission scheme characterized by high cycling rate of the limited water resource was formed and consequently all the nonpotable water consumption was covered by the reclaimed water. Environmental lakes integrated with multi-functions of quantity regulation and quality stabilization of the reclaimed water were introduced in the system configuration and stepwise use of the reclaimed water was observed successfully. As a result of the system operation, main pollutants were well removed and the quality of reclaimed water can reach the demands of various non potable reuse purposes. Water bodies on campus prove to be of good quality of surface water. The project accomplished the minimum emission of discharged water and maximum use efficiency of water resource. It was proven to be feasible based on the technical and economic evaluation. This study provided a model case for future urban development in the water-deficient regions.

Monitoring and validation of decentralised water and wastewater systems for increased uptake

Decentralised water and wastewater systems are being implemented to meet growing demand for municipal services either in combination with centralised systems or as standalone systems. In Australia, there has been increased investment in decentralised water and wastewater systems in response to the capacity constraints of existing centralised systems, an extended period of below average rainfall, uncertainly in traditional water sources due to potential climate change impacts, and the need to reduce the environmental impact of urban development. The implementation of decentralised water systems as a mainstream practice at different development scales is impeded by the knowledge gaps on their actual performance in a range of development types and settings. As the wide-spread uptake of these approaches in modern cities is relatively new compared to centralised approaches, there is limited information available on their planning, design, implementation, reliability and robustness. This paper presents a number of case studies where monitoring studies are under way to validate the performance of decentralised water and wastewater systems. The results from these case studies show the yield and reliability of these decentralised systems, as well as the associated energy demand and ecological footprint. The outputs from these case studies, and other monitoring studies, are important in improving decentralised system design guidelines and developing industry wide management norms for the operation and maintenance of decentralised systems.

Co-governing decentralised water systems: an analytical framework

Current discourses in urban water management emphasise a diversity of water sources and scales of infrastructure for resilience and adaptability. During the last 2 decades, in particular, various small-scale systems emerged and developed so that the debate has largely moved from centralised versus decentralised water systems toward governing integrated and networked systems of provision and consumption where small-scale technologies are embedded in large-scale centralised infrastructures. However, while centralised systems have established boundaries of ownership and management, decentralised water systems (such as stormwater harvesting technologies for the street, allotment/house scales) do not, therefore the viability for adoption and/or continued use of decentralised water systems is challenged. This paper brings together insights from the literature on public sector governance, co-production and social practices model to develop an analytical framework for co-governing such systems. The framework provides urban water practitioners with guidance when designing co-governance arrangements for decentralised water systems so that these systems continue to exist, and become widely adopted, within the established urban water regime.