Here, the salty water, known as brine, is extracted. The borehole for this reaches a depth of 1,296 meters. However, the brine does not need to be lifted from such a great depth because the pressure within the Earth places the resting water level of the deep water at about 80 meters below the Earth's surface.

To bring it to the surface, a submersible pump is installed at a depth of 250 meters in the borehole. This pump is 16 meters long and has a power of 293 kilowatts. At full capacity, it can extract about 150 cubic meters of brine per hour. For major maintenance or pump replacement, the well housing, including the facade and roof, can be removed. It is specifically fastened to the foundation with bolts for this purpose.

The brine flows in an ancient riverbed nearly 1,300 meters deep, dating back to the dinosaur era. The Postera layer there was formed 201 to 252 million years ago and is attributed to the Triassic period. During this time, the first mammals, the therapsids, evolved.

During the exploration of the brine reservoir, known as an aquifer, it was discovered that the sandstone beneath Schwerin is exceptionally productive with large pores. Therefore, future plants are planned with a greater extraction volume and thus higher heat output. However, the relatively young and extraordinarily porous sandstone also brings up more sand than initially anticipated. This is not an issue for the extraction pump. To protect the downstream technical equipment as best as possible, additional filters were retrofitted next to the well house in 2024. The extracted brine first passes through these two backwash filters before being transported via an underground pipeline to the geothermal heating plant.

From the very moment of extraction, the brine must not come into contact with oxygen. Oxygen would cause the iron in the brine to oxidize and precipitate as iron oxide. To prevent this, nitrogen is added to the brine system, protecting the technical equipment.