Urban water systems worldwide need integrated, cross-sectoral innovations to anticipate developments like climate change and population growth. Development and implementation of such innovations is challenging due to the operational and sectoral mindset of organizations in which these innovations take place. This study uses the concept of ambidexterity to get a better understanding of how organizations responsible for urban water management deal with the tension between operation and the need for innovation. We focused on Amsterdam and Rotterdam, two Dutch cities that are global frontrunners in urban water management. Combining a desk study with 25 semi-structured interviews, we found four mechanisms to manage innovation and operation tensions: network, hierarchical, process and human-resource mechnanisms. Different from the literature on ambidexterity, our empirical findings show that the connection between operation and innovation is dominated by networks rather than by executives. Hierarchical mechanisms could be used to complement this, catalyzing innovation or formalizing it.

Urban water systems are under increased pressure from ongoing developments like climate change, population growth and urbanization. While it is clear that current urban water challenges need a more integrated approach, practitioners disagree on what such an integrated approach means exactly. Integration could therefore be described as a wicked problem, with practitioners having different understandings of integration, as well as the opportunities and challenges they should focus on; e.g., climate adaptation, resource recovery or collective replacement. This lack of consensus challenges decision-making, and thus the implementation of integration. To foster urban water systems integration, this study uses Q methodology to explore the different perspectives that Dutch urban water practitioners have on integration for future urban water systems. Our analysis reveals four salient perspectives: perspective 1 sees coordination as a means to make the system future-proof, perspective 2 focuses on climate adaptation, perspective 3 aims for recovery, and perspective 4 is all about efficiency and being in control. While all perspectives acknowledge that traditional urban water practices need to change, they differ on which sustainability challenges are considered most important and what means should be used. Practitioners need to understand these differences to deal effectively with the wicked nature of integration.

Despite being widely implemented, sustainable urban drainage systems (SUDS) do not always function flawlessly. While SUDS have been tested extensively and seem to perform well on a laboratory or pilot scale, practitioners’ experience is different: failures in SUDS occur regularly in practice, resulting in malfunctioning systems, water nuisance and high costs. To anticipate their malfunctioning, and thus to improve their performance, a better understanding of failures occurring in SUDS and their underlying causes is needed. Based on an explorative case-study approach, consisting of site visits and semi-structured interviews with urban water professionals, this study presents an inventory of technical failures in SUDS and an analysis of their root causes. In total, 70 cases in 11 Dutch municipalities have been documented. The results show that the interfaces between SUDS and other urban systems are prominent failure locations. In addition, we found that failures originate from the entire development process of SUDS, i.e., from the design, construction and user/maintenance phase. With respect to the causes underlying these failures, our results show that these are mainly socio-institutional in nature. These are valuable insights for both practitioners and scholars, contributing to a renewed socio-technical urban water system with more sustainable water management practices.

Climate change and urbanization, as well as growing environmental and economic concerns, highlight the limitations of traditional wastewater practices and thereby challenge the management of urban water systems. Both in theory and in practice, it has been widely acknowledged that the challenges of the twenty-first century require solutions that address problems in a more integrated way. Although the demand for integration is obvious, implementation has proved challenging because of the complexity and uncertainty involved. In addition, the urban water literature contains a wide diversity of approaches to integration, each contribution having its own understanding of the term, as well as how to deal with the complexity that comes with it. In this article, we take a first step in supporting both decision-making and decision-makers in urban water systems integration. First, we work towards a more comprehensive perspective on integration in urban water management; one that uses and structures the variety of existing approaches. In so doing, we introduce a typology of urban water systems integration that distinguishes between geographical, physical, informational, and project-based forms. Second, we explore the implications that such integrated solutions bring for decision-makers. They will be faced with additional uncertainty arising (1) at the interfaces of previously unconnected systems and (2) from the social and institutional changes that systems integration requires. Finally, we draft three decision-making challenges that come with integration and provide some possibilities for dealing with them.

The accumulation of FOG (Fat, Oil and Grease) deposits in sewer pumping stations results in an increase in maintenance costs, malfunctioning of pumps and, a potential increase of wastewater spills in receiving open water bodies. It is thought that a variety of parameters (e.g. geometry of the pump sump, pump operation, socioeconomic parameters of the catchment) influences the built-up of FOG. Based on a database containing data of 126 pumping stations located in five Dutch municipalities a statistical model was built. It is shown that 3 parameters are most significant in explaining the occurrence of FOG deposits: mean income of the population in a catchment, the amount of energy (kinetic and potential) per m³ per day and the density of restaurants, bars and hotels in a catchment. Further it is shown that there are significant differences between municipalities that can be traced back to the local ‘design paradigm’. For example, in Amsterdam, the design philosophy of discharging in the pump sump under the water surface (and hence maintaining a low level of turbulence in the pump sump) results in an increase of the probability of the formation of FOG.