For years, Petra Liesenfeld has witnessed falling groundwater levels in her hometown of Baruth. She has to water her garden far more often than she used to, and has seen some local trees completely dry out. At the same time, two beverage companies are looking to expand production in the area.

Mineral water has been bottled in the small town of Baruth, which lies around 60 kilometers (37 miles) south of Berlin, since the 1990s. The site is now run by Red Bull and Austrian beverage producer Rauch, who are planning a new canning factory and additional facilities. All in the middle of a water protection area.

The Baruth waterworks are licensed to extract a fixed amount of groundwater each year, just 8% of which goes to supply the town's roughly 4,300 residents with drinking water. The remaining 92% is reserved for Red Bull and Rauch, and is enough to cover the drinking water needs of 57,000 people. But exactly how much water the companies currently use is not made public.

This is legal under the existing contracts, said Peter Ilk, who until recently was the town's mayor and is considered a driving force behind the region's industrialization. He sees no problem with the way water is managed.

"We have always given priority to supplying the population. That is also written into all the contracts," he said, adding that it stands to reason that the companies need more than the town's residents. "That's how you end up with this ratio of around one to 10 in terms of consumption."

Old data informing current decisions

Hydrogeologist Irina Engelhardt from the Technical University in Berlin takes a more critical view, pointing out that the contracts, which are around 30 years old, are based on outdated information. Since then, groundwater levels, groundwater recharge and the way land is used have all changed significantly.

"I am concerned at how the water situation is developing in the state of Brandenburg," she said. "The volume that is actually available is currently being overestimated by the Brandenburg authorities."

Together with a citizens' initiative made up of local residents, she is calling for new, independent assessments — and for clear and open communication. Though the authorities granted them access to some groundwater monitoring documents, large parts were redacted, which some residents believe is a move to conceal information about changes in levels.

"We ask ourselves why there can't be more transparency if everything is aboveboard. Why isn't the public allowed to know?" said Petra Liesenfeld.

Exactly how much Red Bull and Rauch pay for their daily extraction of up to 7 million liters of groundwater is not public information.

DW approached both companies for comment, but by the time of publication, neither had responded.

For drought researcher Andreas Marx, this lack of transparency is problematic.

"By law, water is a public commodity. It cannot be privately owned. So, in my view, every decision made and every contract signed over its use should be open to the public," he said.

How dry is Brandenburg?

Germany — and Brandenburg — are still water-rich regions. Marx, who heads the Drought Monitor at the Helmholtz Centre for Environmental Research, said "the challenge isn't adapting to permanent water scarcity but learning how to cope with dry periods that can last two or even three years."

Nevertheless, the water balance in the state, as elsewhere in Germany, is definitely changing. Since the 2018 drought, groundwater has not been sufficiently replenished in many places and higher temperatures and increasing evaporation are making it harder for reserves in deeper soil layers to recover.

This could cause even more problems in the future, as 95% of Brandenburg's drinking water comes from groundwater.

How much water does the energy transition need?

In Grünheide, in the eastern part of the state of Brandenburg, Tesla's Gigafactory has a permit to extract up to 1.4 million cubic meters of water per year and is planning to expand production to as many as 7,500 vehicles per week. Meanwhile, in recent years, residents have repeatedly been urged to save water.

"Many projects, including new schools and kindergartens, were put on hold because there simply wasn't enough water," said local resident Manu Hoyer.

Marx said when water resources are scarce, residents are generally the first to face restrictions because they're the easiest to limit. "Industrial companies are rarely restricted, because the economic consequences are much harder to assess," he said.

Copper for the energy transition — a risk to groundwater?

The potential for an additional water problem is brewing further south in Spremberg, where a large mine is planned. Over the coming decades, copper — which is essential for power grids, electric vehicles and the transition to clean energy — is set to be extracted from depths of up to 1,200 meters (about 4,000 feet).

Geotechnical engineer Michael Pfeifer said mine water from such depths is highly saline and sulfurous and requires extensive treatment.

"But the treatment plant proposed so far is nowhere near capable of doing what's actually required to clean the water to a standard where it could be safely discharged into the Spree," Pfeiffer said of the river that flows north toward Berlin.

The river water is already affected by decades of lignite mining in the region, and it is facing additional pressures. With lignite extraction set to end by 2038, the groundwater currently pumped into the Spree from the mines will no longer be available. As a result, dry summers could see the river carrying up to 75% less water, with far-reaching consequences for water resources all the way to Berlin.

Could rainfall be stored for future use?

One possible solution to the water problems facing the state around the German capital is artificial groundwater recharge, where excess water from periods of high rainfall is stored underground and used later.

Hydrogeologist Engelhardt is researching where this could be possible in the region.

"There are areas in Brandenburg — such as where Tesla is now located — where artificial groundwater recharge could meet almost the entire demand of the local drinking water supplier," she said.

However, enough available water is necessary for this solution to work.

For drought researcher Marx, one question remains crucial: What rules should determine how water is distributed between the population, agriculture, nature and industry during prolonged dry periods?

As the global temperature continues to rise, it's not just an issue reserved for Brandenburg — or even Germany.

This article was originally written in German.

Correction, August 19, 2026: An earlier version of this article misspelled the name of geotechnical engineer Michael Pfeifer. DW apologizes for the error.