United for the Future of Water and Resilient Sponge Cities

Water is our most precious resource – and it stands at the heart of urban transformation. At the 3rd cross-state Water Congress Berlin-Brandenburg-Saxony on May 12 and 13, 2025, around 250 experts from politics, business, and science discussed innovative solutions for a secure, sustainable, and resilient water supply. Green City Solutions participated with CEO Peter Sänger as a driving force for bio-digital innovations and the sponge city concept.

Photos: Konstantin Gastmann

The Challenges: Climate Change, Structural Transformation, Water Scarcity

The pressure to act is high: climate change, population growth, and the structural transformation resulting from the coal phase-out are intensifying conflicts over water use. The next ten years will be crucial for developing viable strategies for water supply in Berlin, Brandenburg, and Saxony. As the Berlin Association of Merchants and Industrialists (Verein Berliner Kaufleute und Industrieller, VBKI) summarizes: “Water is becoming a scarce resource. Climate change and structural transformation are intensifying usage conflicts – prioritization and viable strategies are urgently needed.”

“Berlin and Brandenburg are among the driest regions in Germany. How can we ensure water supply in our region?” asked rbb24. The Water Congress provided an ideal platform to work together on solutions for a resilient, sustainable, and livable city of the future.

 

Sponge City: Moss as Green Sponges for the City of Tomorrow

A central topic of the congress was the sponge city principle – a future model for sustainable urban development and climate adaptation. Sponge city means: “Rainwater should not simply flow into waterways via the sewage system, but should be collected and stored for use where it is needed.” As a spokesperson for the Association of Municipal Enterprises (Verbands Kommunaler Unternehmen, VKU) told rbb: “Stored rainwater can be used for irrigation, saving valuable drinking water.”

Green City Solutions presented bio-digital innovations such as WallBreeze, CityTree, and CityBreeze, which harness the natural abilities of mosses as “green sponges”. These store and evaporate water, purify the air and sustainably improve the urban climate. In this way, these natural filters make an active contribution to climate adaptation, enhancing urban quality of life and protecting valuable resources.

Our CEO Peter Sänger spoke in his presentation at the Water Congress 2025 about the most important resource – besides air – and how the sponge city concept can be put into practice.

Photo: Konstantin Gastmann

Excursions, Exchange and Innovative Pitches

“Coordination instead of competition was one of the most important topics of the day.” The program included excursions to sponge city projects with the Berlin Rainwater Agency, a networking evening on the Spree, and four pitches from innovative companies such as Green City Solutions, LuxChemtech and KWB Energiesysteme.

A heartfelt thank you to all participants, contributors, and organizers! We look forward to further exchange and inspiring collaborations.

For example, Stephan Gruhlke, mayoral candidate of Eichwalde, was inspired after Peter Sänger’s presentation:

“I took away inspiring ideas on natural air purification. A visit to the manufacturer is already scheduled.”

This visit has since taken place, as he was “curious about innovative ideas” and was “informed on site by the experts about a great concept. His conclusion: “Here, solutions are being developed that use highly sophisticated moss mat technology for natural air purification in both indoor and outdoor areas.”

But it didn’t stop at theory: “The municipality of Schönefeld and the city of Wildau have already been convinced by this concept. I was able to see the products in practical use. Depending on the model, the modules provide the same performance as 20 to almost 80 free-standing trees in nature. These can also be combined with displays for advertising or information.”

Regional, Connected, and Future-Oriented: The Sponge City as a Key to Resilient Cities

“In Germany, the first drought reports of the season are already accumulating. The perfect timing” for the Water Congress 2025. The event made it clear: the sponge city is a key to climate-resilient, livable, and sustainable cities of the future. Moss-based innovations such as WallBreeze, CityTree, and CityBreeze make an active contribution to climate adaptation, air purification, and resource protection.

The coming years will be decisive – now is the time to work together on solutions for a resilient water future.