Groundwater resources in Germany

Groundwater is also a vital and indispensable resource in Germany. For a large part of the population, it is the only source for meeting their daily water needs. In the public water supply, which mainly supplies households, public institutions and small businesses with water, groundwater is the most frequently extracted resource with a share of more than 60 %, while in the non-public water supply, which mainly supplies industrial companies with water, groundwater plays a minor role with a share of less than 15 %.

Public water supply of Germany 2019 according to DESTATIS Source: BGR

According to the German Association of Energy and Water Industry (BDEW), the annual production volume of public water utilities has fallen from just under 6.77 billion cubic metres to 5.45 billion m³ over the last 30 years, i.e. by just under 20 % or just over 1.3 billion m³. Annual groundwater extraction, including spring water, has fallen continuously since 1990 from around 4.8 billion m³ and has stabilised at around 3.6 billion m³ since 2010. Since 2015, both the total volume of water extracted and the volume of groundwater and spring water have increased slightly.

According to the Federal Statistical Office, a total of 5.35 billion m³ of water was extracted by the public water supply in 2019, of which 3.78 billion m³ was groundwater and spring water (70.6 %). A total of 15.36 billion m³ of water was extracted by the non-public water supply in 2019, of which 2.29 billion m³ was groundwater and spring water (14.9 %).

A total of 20.71 billion m³ of water was extracted in Germany in 2019. River water dominates with 12 billion m³ (58 %) and is mainly used for cooling purposes in power plants. Groundwater and spring water account for 6.1 billion m³ (29.3 %), followed by lake and reservoir water with 1 billion m³ (5 %), riverbank filtration with 0.9 billion m³ (4.2 %) and enhanced groundwater recharge with 0.5 billion m³ (2.4 %). The distribution of the different water types among the individual economic sectors is shown in this figure.

Total water extraction in Germany 1991 - 2019 according to DESTATIS. Source: BGR

Total water extraction in Germany, i.e. the sum of public and non-public water supply, is in sharp decline and has more than halved in the last 30 years. The volume of water abstracted has fallen from just over 46 billion m³ to around 21 billion m³.

In relation to the average groundwater recharge of 48.2 billion m³/a in the period under consideration 1961-1990 (average water balance in Germany 1961-1990), the 6.1 billion m³ of groundwater and spring water extracted in 2019 corresponds to 12.6 %. Converted to the area of Germany, this corresponds to a water table of 17 mm. Comparable data on current groundwater recharge in Germany are not currently available, but it is assumed that groundwater recharge has decreased slightly over the period 1991-2020.

Web application GRUVO - Groundwater levels and forecasts for Germany Source: BGR

A relatively simple method of assessing the groundwater situation in Germany is to monitor and analyse groundwater levels throughout the country. This is done using the GRUVO application. A machine-learning process enables a standardised nationwide representation of past, present and future groundwater levels, which is updated at regular intervals. Groundwater levels at approximately 120 reference monitoring sites and more than 4,200 associated cluster monitoring sites are visualised in five status classes for the reference period 1991-2020.

Groundwater extractions of public and other water uses vary considerably between the federal states in Germany, as the figures in Table 1 and Table 2 illustrate. The public water supply in Bremen, Hamburg, Schleswig-Holstein, and Saarland is based almost 100 % on groundwater and spring water, followed by Brandenburg (87.6 %), Hesse (87 %), Lower Saxony (86.9 %), Rhineland-Palatinate (84.7 %) as well as Bavaria with 84.2 % and Mecklenburg-Vorpommern with 84.1 % from groundwater and spring water. In a comparison of the federal states, North Rhine-Westphalia (48.8 %), Saxony-Anhalt (46.2 %), Saxony (32.4 %) and Berlin are at the lower end with 24.1 % of groundwater and spring water in the public water supply. Berlin obtains most of its drinking water from riverbank filtrate, while in Saxony, Saxony-Anhalt and Thuringia around 40 % of drinking water is obtained from lakes and reservoirs.

Non-public water supply of Germany 2019 according to DESTATIS Source: BGR

Groundwater plays a relatively minor role for the non-public water suppliers. Basically, river water covers most water demands and is mainly used for cooling purposes in power generation plants. The proportion of groundwater and spring water for other sectors is higher than the proportion of river water only in Saxony (66.5 %) and in Brandenburg (55.9 %).

In absolute figures, Bavaria extracts the most groundwater including spring water for public water supplies with an annual extracted volume of 808 million m³ followed by North Rhine-Westphalia (587 million m³) as well as Lower Saxony with 526 million m³ and Baden-Württemberg with 484 million m³ (Table 1). In terms of non-public water supply, North Rhine-Westphalia clearly stands out with 766 million m³ of groundwater and spring water extraction due to water-intensive steel, chemical and mining industries located there. It is followed by Lower Saxony with 280 million m³, Bavaria with 278 million m³, Brandenburg with 252 million m³ and Saxony with 216 million m³ of groundwater and spring water extraction (Table 2).

Groundwater resources of Germany by aquifer type, extent and productivity Source: BGR

Due to the geological setting and hydrogeological conditions in Germany, groundwater resources vary across the country (see figure). About 40 % of the country has porous aquifers, some of which are very productive. About 21 % are fractured and karst aquifers. The rest of the country is covered by porous or fractured aquitards that have only local and limited or no significant groundwater potential.

The largest area of continuous high-yield aquifers is the North German Plain, which is mainly made up of thick layers of Quaternary and Tertiary sand and gravel. Particularly important are the aquifers formed in buried valleys or along deeper palaeochannels of the last glaciation. The Quaternary and Tertiary deposits of the Alpine foothills also form extensive and productive porous aquifers. In addition, the entire Upper Rhine Graben is an area of highly productive groundwater resources. In the Lower Rhine Basin and in the Lower Rhine Plain, thick, partly overlying and productive porous aquifers form some of the most important groundwater resources in Germany. Most of the major groundwater pumping public waterworks are located in these areas of the above-mentioned, significant and very productive alluvial deposits.

Type of aquifers and location of public waterworks of Germany Source: BGR

Groundwater resources of local importance are found in the central mountain ranges, especially in the limestones of the Swabian and Franconian Jurassic and in Thuringia, in the lacustrine limestones between the River Main and the Black Forest, in the carbonate deposits of eastern Westphalia (karst aquifers), in the sandstones of the Palatinate Forest, Black Forest, Spessart and Solling and, last but not least, in the basalts of the Vogelsberg (fractured aquifers).

The central mountain ranges, such as the Rhenish Slate Mountains, the Harz, Thuringian and Bavarian Forests, the Ore Mountains and the Black Forest, are generally characterised by low-yield aquifers, consisting mainly of shale, crystalline schist and plutonic rocks. However, local sandy-gravelly valley deposits and debris fans in the foothills, local deposits of karst limestone and dolomite in the Schiefergebirge can be considered as local groundwater resources.

A comprehensive description of the regional groundwater situation in Germany can be found in the joint publication of the State Geological Surveys (SGD) and the BGR entitled "Regional Hydrogeology of Germany - The aquifers: extent, rocks, storage conditions, protection and importance".