Satellite measurements show that water reservoirs in Germany have been losing volume for years. Even periods of heavy rain no longer compensate for the deficits. An evaluation by the GFZ Helmholtz Center for Georesearch supports the development with figures.

The data comes from the GRACE satellites, which have been recording changes in water volume worldwide since 2002. At the end of 2025, Germany will have a deficit of around 25 billion tons of water compared to the long-term average. Two years earlier the deficit was around ten billion tons.

Water reservoirs in Germany are getting out of balance

Looking at the global data shows a clear shift. Conditions with “normal” water storage are becoming less common. In 2009, their share was around 75 percent of the land area. By 2025, only about a third of this will remain.

At the same time, the proportion of dry areas is growing rapidly. It rose from 12 to around 43 percent. This means that the area with a water shortage has more than tripled. “Globally, the extremes of water storage are increasing,” says the evaluation. Humid regions, on the other hand, remain largely stable. The problem lies primarily in the spread of drought.

Europe is losing water storage – Germany is following a clear trend

The data shows clear differences between the world regions. A total of 61 large river basins were evaluated. Water storage is consistently declining in Europe and the Middle East. Africa is an exception and is recording increases in parts.

For Western Europe, to which Germany belongs, The decline begins around 2014. “In Europe and the Middle East, all catchments show a decrease in water storage,” according to the analysis. This makes the region one of the particularly affected areas. The loss of glacial ice, for example in Iceland, is also reinforcing this trend.

Germany has been losing water for years – short recovery remains the exception

In Germany, the development since 2018 has been particularly noticeable. Several dry years in a row have put a lot of strain on the water reservoirs. There was a brief relief in 2024. This year there was around 15 percent more precipitation than usual. The memories were able to temporarily recover.

But the situation turned around again in 2025. Rainfall was around 18 percent below average. At the same time the temperatures rose. This caused more water to evaporate before it could reach soil and groundwater. The development is clearly reflected in the numbers:

• Soils dry out more quickly
• Plants release more water into the air
• It is harder for rain to seep into deeper layers

As a result, some of the precipitation is lost directly. “The ongoing widespread drought since 2018 is clearly visible,” says the evaluation. Even wet years no longer completely compensate for the deficit.

The changes occur beneath the surface

The decline primarily affects water that is not immediately visible. These include groundwater, soil moisture and glaciers. These reserves are crucial for a stable supply.

The first effects are already visible:

• falling water levels
• drier soils
• lower harvests

For everyday life this means:

• Agriculture must adapt
• Water is becoming scarcer regionally
• Usage conflicts are increasing

The significance of satellite data lies in their long duration. Since 2002, the GRACE missions have been measuring changes in water volume on a monthly basis. In this way, short-term fluctuations can be distinguished from real trends. Over this period of time, a consistent pattern emerges that speaks for itself: the water reservoirs quickly lose volume in warm phases and only recover slowly – overall, they become increasingly out of balance.

Briefly summarized:

• Germany’s water reservoirs have been losing significant volume for years; By 2025, around 25 billion tons of water will be missing, despite some rainy years.
• Extremes are increasing worldwide: the proportion of normal water conditions is falling sharply, while dry regions are more than tripling and Europe is particularly affected.
• Heat accelerates the loss: water evaporates more quickly, percolates more slowly and even wet years can no longer compensate for the deficit.

By Eva Schmitt