Rainwater as a resource instead of a risk – that is the motto of future-oriented urban design. Rainwater management is no longer just a technical side issue, but is becoming a strategic lever for climate-adapted, green and liveable cities. But how can the transition from sewer system to sponge city be achieved? And what role do planners, landscape architects and local authorities play in this transformation? It’s time to rethink rainwater management – as an integral part of urban design and a driver of sustainable urban development.
- Why rainwater management today is more than just drainage – and why it plays a key role in urban design.
- The most important technical and design principles of sustainable rainwater management: from decentralized systems to sponge cities.
- Concrete examples from Germany, Austria and Switzerland that show how rainwater shapes urban spaces.
- Current challenges: Legal framework conditions, competition for space, acceptance and financing.
- Interdisciplinary cooperation: How planners, city administrations and citizens develop solutions together.
- Rainwater as a driver for biodiversity, microclimate, quality of life and urban resilience.
- Innovative tools and digital planning instruments for rainwater management in the context of urban design.
- An outlook: How rainwater management makes urban transformations visible and becomes a trendsetter for sustainable urban development.
From wastewater problem to design resource: the new role of rainwater in the city
Anyone talking about urban design today simply cannot ignore rainwater management. Whereas in the past the aim was to “channel away” rainwater as quickly and efficiently as possible, we are now experiencing a turning point: Rainwater is being recognized as a precious resource that needs to be used, stored and integrated into the design. Cities are faced with the dual challenge of dealing with the consequences of climate change – heavy rainfall, flooding, heat islands – and at the same time creating liveable, green spaces. The classic sewer system, once celebrated as a technical masterpiece, has long since reached its limits. It can neither buffer heavy rainfall events nor improve the urban climate or promote biodiversity.
Modern rainwater management therefore does not just start at the drainage pipe, but thinks about water from the very beginning – from the roof to the urban landscape. The vision: every property, every neighborhood, every public space becomes part of a networked water cycle. Rainwater is to be retained, infiltrated, evaporated or used as decentrally as possible. The buzzword “sponge city” aptly describes this paradigm shift. A sponge city absorbs rainwater, stores it and slowly releases it again – just like a natural soil.
For planners, this means that rainwater management is no longer just a task for engineers, but also a question of design, choice of materials, vegetation and urban spatial conception. The aim is to make water visible and tangible instead of hiding it in underground channels. From green roofs and trough-trench systems to open watercourses – the possibilities are diverse and inspiring.
This new role of rainwater requires close cooperation between urban planning, landscape architecture, engineering and administration. This is the only way to create solutions that not only function technically, but also shape the cityscape and enhance the quality of life. Cities such as Berlin, Zurich and Vienna show this: Rainwater can become a design element, an identity-creating resource and a driver of innovation for sustainable neighborhoods.
But the path to achieving this is challenging. Existing structures need to be transformed, competition for space needs to be moderated and new ways of thinking need to be established. Rainwater management is therefore much more than a technical discipline – it is a driver of change in urban design. Those who take bold action here make a virtue of necessity and transform rainwater from a problem to a design partner.
Technical and design principles: From decentralized retention to the sponge city
The implementation of sustainable rainwater management begins with a fundamental departure from centralized, technical thinking. Instead of directing the water to the nearest sewage treatment plant as quickly as possible, modern concepts focus on decentralized retention, evaporation and infiltration – the keyword here is creating retention space. Technical, ecological and design aspects are interwoven into a holistic system.
A key element is the so-called “trough-trench technology”. This consists of shallow, planted troughs that absorb rainwater and slowly transfer it to the infiltration trenches below – trenches filled with gravel. The water seeps away, is filtered and reaches the groundwater. At the same time, a green, visually appealing element is created in the street or park space, which promotes recreation and biodiversity. Even more elegant are open watercourses and urban streams that deliberately stage rainwater and guide it through urban spaces as tangible water veins.
Green roofs and façades play a dual role in this context: they store water, delay runoff and cool the environment through evaporation. They also provide a habitat for insects and birds – a real benefit for urban nature. Rainwater harvesting systems for watering green spaces or flushing toilets are also increasingly being integrated into new construction projects. They not only reduce drinking water consumption, but also make the use of water a direct experience.
The design of such systems is an art in itself. The aim is to combine technical function and aesthetic quality. Surfaces must be modeled in such a way that they absorb water without flooding. Plant selection, soil structure, materials – all of these must be adapted to rainfall, site conditions and usage requirements. A good example are the rainwater gardens in Copenhagen or the attractive retention areas in Hamburg’s Oberhafen district, which appear as temporary water areas during heavy rainfall and serve as play and recreation areas in everyday life.
The sponge city is not a fixed scheme, but a flexible principle. Every location, every neighborhood needs a tailor-made solution. Thinking in systems is crucial: Roof areas, streets, squares, parks and private gardens are networked in such a way that rainwater becomes the connecting element of the urban landscape. The earlier rainwater management is integrated into the planning, the more effective and economical the result. If you only look for a drainage solution at the end, you have already lost.
At the same time, the importance of digital planning tools is growing. GIS analyses, hydrological simulation models and digital twins make it possible to precisely forecast rainfall runoff, retention potential and flooding risks right from the design stage. They help to compare variants, make optimum use of space and react flexibly to changing climate conditions. The digital and the green city are thus growing together in the truest sense of the word.
Practical examples from German-speaking countries: rainwater as urban added value
Theory is all well and good, but what matters are the built examples that show how rainwater management can shape urban spaces. In Germany, Austria and Switzerland, there is now an impressive range of projects that can serve as a blueprint for other cities – provided you have the courage to break new ground.
A prime example is the Berlin project “Flussbad Berlin”. Here, a former Spree arm is being converted into a publicly accessible swimming pool. Rainwater from adjacent neighborhoods is pre-cleaned in near-natural filter zones before it enters the canal. The result: a multifunctional urban space that combines water quality, quality of stay and urban nature. The project impressively demonstrates how rainwater management can enrich urban life – when technical, ecological and social aspects are considered together.
Hamburg is also setting a good example. In the “Oberhafenquartier” urban development area, retention areas and trough-trench systems have been declared the design leitmotifs of the district. The water surfaces are not only functional buffers in the event of heavy rainfall, but also formative elements for recreation, play and encounters. Rainwater is seen as a design partner – not as a disruptive factor.
In Zurich, on the other hand, rainwater is used specifically to cool streets. Unsealed surfaces, tree-lined infiltration basins and green spaces ensure that rainwater seeps away locally, evaporates and improves the microclimate. The “Pfingstweidpark” example shows how innovative water management and high-quality open space design can go hand in hand. The result is attractive, resilient urban spaces that need not fear climate change.
Smaller cities are also making their mark: In Graz, the “Smart City Lab” has been equipped with decentralized water systems that use rainwater for irrigation and evaporation. In Basel, multifunctional green spaces are being created in new districts that serve as rainwater buffers, playgrounds and biodiversity reservoirs all at the same time. Such projects encourage us to think outside the box and see rainwater as a design opportunity.
What all successful examples have in common is their integrative approach. Planners, city administrations, engineers and citizens work together on solutions that are ecologically, socially and aesthetically convincing. Rainwater management thus becomes a driver of innovation and identity in urban design – and the key to resilient, liveable cities.
Challenges and prospects: Between competition for space, acceptance and digital transformation
As convincing as the examples are, the road to comprehensive rainwater management is a rocky one. In practice, planners and local authorities face numerous hurdles – from legal restrictions and competition for land to a lack of acceptance among investors and users. The central question remains: How can rainwater management be established as a natural part of urban design?
German building law continues to be a major obstacle. The requirements for infiltration, retention and use of rainwater are often complex and vary from state to state. Approval procedures are protracted and the scope for innovation is restricted by technical regulations. This calls for creative solutions, courageous administrations and close coordination between specialist departments in order to increase the scope for sustainable rainwater management.
Added to this is the competition for space. In densely populated cities, land is scarce – every function has to fight for its place. Rainwater management is often still seen as a consumer of land, not as a provider of added value. This makes it all the more important to develop multifunctional solutions that combine retention, play, recreation and biodiversity in one area. This creates synergies that convince everyone involved.
Acceptance is also a sticking point. Developers and investors often fear additional costs or restrictions on use. Users worry about mosquitoes, odors or supposedly “wet” areas. Only transparency, good communication and a convincing design can help here. When rainwater management is visible, tangible and attractive, it becomes an identity feature of a neighborhood – not a nuisance.
Digitalization opens up new opportunities. Hydrological simulations, digital twins and real-time data make it possible to precisely plan, control and monitor rainwater processes. This allows risks to be minimized, potential to be exploited and citizens to be actively involved in design processes. Digital tools make the complexity of rainwater management manageable – and open up new ways of making urban spaces fit for the future.
However, the biggest challenge remains to establish rainwater management as a natural part of everyday urban life. This requires committed planners, courageous administrations and informed citizens. Only if all stakeholders pull together will the vision of the sponge city become a living reality. The good news is that the tools are available, the know-how is growing – and the social pressure to make cities climate-resilient and liveable continues to increase.
Conclusion: Rainwater management as a future task for the city and landscape
Today, rainwater management is at the heart of sustainable urban design. It is far more than a technical compulsory program – it is a creative, design and social project. Anyone who understands rainwater as a resource can make cities climate-resilient, green and liveable. The examples from German-speaking countries show this: With courage, creativity and interdisciplinary cooperation, solutions can be developed that are ecologically convincing, impress in terms of design and enrich urban life.
The future belongs to the sponge city – a city that not only manages rainwater, but uses it, makes it visible and incorporates it into its DNA. This is an exciting task for planners, landscape architects and city administrations. The challenge is to combine technical innovation with design, to involve citizens and to creatively overcome regulatory hurdles. Digitalization offers new tools for planning, visualizing and optimizing rainwater processes.
Those who invest in rainwater management today are shaping the city of tomorrow. It is no longer about drainage, but about enabling urban life – despite and precisely because of the water. Rainwater thus becomes a stimulus for biodiversity, a catalyst for quality of life and a link between technology and design.
Garten und Landschaft keeps its finger on the pulse of this development – with specialist knowledge, inspiration and a critical eye on trends and challenges. Because one thing is certain: the city of the future will not only be built, it will be designed – and water will play the main role in this.
Urban design and rainwater management are inextricably linked. Those who understand this will plan in a resilient, courageous and forward-looking way. Welcome to the new urban landscape – with rain as a friend, not an enemy.











