Dry metropolis – how can Berlin protect its drinking water?

Major European cities like London, Paris, and Berlin need groundwater resources to provide its inhabitants with drinking water. However, Berlin stands out with a unique drinking water system that relies entirely on groundwater. This complete dependence makes Berlin particularly vulnerable to threats such as climate change and Germany’s upcoming coal phase-out. German researchers are using computer simulations to predict climate trends and find solutions to safeguard Berlin’s crucial water resources. 

Supplying around 3.8 million people, Berlin's drinking water system relies significantly on a process called bank filtration, whereby water from the Havel and Spree Rivers and neighbouring lakes is drawn through the soil. The water is naturally filtered through sand and gravel, which removes impurities before the water is used, treated, and returned to the ecosystem.  

“Currently, we have the water quality that we need. But the last five years were really dry years and this kind of showed us already limits of the system that we are using here,” said Josefine Filter of Berliner Wasserbetriebe in Berlin. 

Changing patterns threaten the water supply 

The average annual rainfall in Berlin has been around 580 litres per square meter in the past years, but climate change is altering rainfall patterns. The region now has more frequent and intense downpours, as well as extended dry periods.  

Adding to this problem is the scheduled closure of the Lusatia coal mine in 2038 that feeds groundwater into the Spree River. The loss of this artificial supply, combined with dry summers, poses a significant risk to Berlin's drinking water. 

Recognising these challenges, the Berlin senate has developed the “Masterplan Water” comprising 32 measures aimed at securing the city’s long-term water supply.   

The European project IMPETUS is providing crucial support by developing climate trend prediction strategies to improve the region’s responses to climate change. The project’s researchers use computer models to simulate how droughts or changes in water bodies could impact Berlin’s drinking water and evaluate how various management strategies would perform under stress, such as extended droughts or the loss of coal mine water in the Spree River. 

They are also exploring ozonation, an advanced treatment process that uses reactive oxygen to break down pollutants like pharmaceutical residues. Already recommended by the European Commission, this method is now being implemented in Berlin and could increase the reuse of treated wastewater, providing a buffer against future droughts. 

“We cannot go on business as usual. And that's the reason we try to have a picture ready, which is not looking on the yearly water demand we have, but on the water demand we have in ten years, in 20 years and then say, okay, we lack it. We don't know if it happens in ten years, if it happens in 15 years, but it will happen. How will you react?”, said Regina Gnirss of Berliner Wasserbetriebe in Berlin. 

A series of new, free-to-use footage and interviews shows how Berlin is preparing for a future of water scarcity and how other cities can learn from its efforts. 

• Video Berlin's Water Crisis
• BRoll Berlin's Water Crisis
• Interviews with:
  • Frauke Bathe, DE
  • Benjamin Creutzfeldt, DE
  • Josefine Filter, ENG & DE
  • Nasrin Hake, ENG & DE
  • Regina Gnirs, ENG & DE
• Press release
• Photos

About the project 

We are all feeling the impacts of climate change here and now. IMPETUS focuses on increasing our resilience. By working with local citizens, policymakers and businesses in demonstration sites around Europe, the project teams are analysing solutions, boosting knowledge, and creating packages of adaptation measures that other communities can use as a pathway towards a climate-neutral and sustainable future. IMPETUS was launched in October 2021 with the objective of turning climate commitments into tangible, urgent actions to protect communities and the planet.