Stuttgart, Germany, July 15, 2026.As meteorologists issue warnings in advance of the next heatwave, the dry conditions in many parts of Germany are intensifying. The water level on Lake Constance is significantly below normal. The river flow on the Danube is lower regionally than it has been in decades, and levels on the Rhine are also falling. Shipping companies, agriculture, industrial firms and water suppliers are under increasing pressure to use resources more efficiently. For cities, towns and villages, one question is becoming ever more pressing: how can water supply be safeguarded in long periods of drought? 

Since the end of June, the city of Stuttgart has severely restricted the withdrawal of water from streams, rivers or lakes in an effort to protect the aquatic environment against the stresses of high temperatures and low water levels.[i] Violations of the restrictions can result in fines of up to 100,000 euros. In its Master Plan for Public Water Supply, the Ministry for the Environment, Climate and Energy Sector of the federal state of Baden-Wuerttemberg projects that, under the current conditions, more than half of all municipalities in the state will be unable to meet peak drinking water demand by 2050.^[ii] The situation in the country as a whole is also stark: according to the GFZ Helmholtz Centre for Geosciences, at the end of 2025, Germany had already lost 25 billion cubic meters of its water volume compared with the long-term average.[iii] This is equivalent to more than half the water in Lake Constance.[iv] 

Dr. Stephan Wasielewski has been focusing on the impact of water scarcity, in both research and practice, for more than a decade. The graduate engineer in environmental sciences earned his doctorate at the University of Stuttgart. Today, he manages the water infrastructure area at Drees & Sommer. Prior to this, he collaborated in drafting the Water Supply Master Plan of the federal state of Baden-Wuerttemberg. He said: “In actual fact, we have enough water in Germany. However, the frequency with which water is getting to the wrong place at the wrong time is increasing. Long-lasting periods of drought alternate periods of intense rainfall. 

But sewer systems and surfaces often cannot cope with the volumes of water. The supply of water has long been about infrastructure and become a location factor.”

In the view of Drees & Sommer’s experts, water must be kept in circulation for longer, losses reduced and the use of available resources optimized:

1. Keeping rainwater where it falls

In many places rainwater is still being dealt with by getting rid of it as quickly as possible This is becoming a problem in times of increasing droughts. Infiltration areas, green roofs, troughs infiltration trench systems or cisterns ensure that rainwater is retained in the soil and improve groundwater reservoirs. Drees & Sommer’s project in Berlin’s Lichtenberg district demonstrates how this works in practice. The local roads and parks department commissioned Drees & Sommer SE to select 24 out of 90 schools for disconnection from the sewage system. In order to keep rainwater where it falls, instead of flowing into the sewage system, green spaces and infiltration areas with troughs and ditches will be created on a total sealed surface area of around 135,000 square meters (roughly the size of 19 soccer pitches).[v]

2. Reducing water losses in the system

Droughts are not the only thing costing money. Failing pipes also contribute to the loss of valuable drinking water: Around 319 million cubic meters of water is lost every year in Germany due to leaking pipes. This corresponds to the annual demand of almost seven million people.[vi] Digital leak detection, tight monitoring and refurbishment of old networks help municipalities to reduce the losses significantly. Since 2023, for example, the municipal utility Stadtwerke Bad Homburg has been collaborating with Preventio, a Frankfurt-based start-up company that uses in-house artificial intelligence (AI) technology to detect leaks at an early stage to prevent larger damage and water losses.[vii]

3. Reusing water

Many uses do not require drinking water. Rainwater, gray water and service water can be used for watering green spaces, flushing the toilets or technical installations, for example. This reduces the consumption of high-quality drinking water. “We need to move beyond the thoughtless system of withdrawal, use and discharge. Sustainable, future-proof regions will be those that reuse water several times and keep water in circulation – this has become a key location factor for businesses too," explains Dr. Stephan Wasielewski. Drees & Sommer is conducting research for Trostberg-based Alzchem Group into how service water from the central wastewater treatment plant can be reclaimed and reused repeatedly in its plants to reduce drinking water consumption of the chemical company.[viii]

4. Managing water withdrawal transparently

When water becomes more scarce, competition among users is heightened. Agriculture, industry, energy supply and municipalities use the same resources. In many cases the parties involved do not know who consumes, when, how much. Digital water registries create transparency regarding withdrawal rights, protected areas and actual water withdrawals.[ix] For instance, the federal state of Rhineland-Palatinate has maintained a fully digital water registry since 2004; other states are still working on creating one. Municipalities and water authorities can access real-time data, identify scarcities at an early stage and respond in a targeted way instead of imposing blanket restrictions across all user groups.

5. Unsealing urban soil and making cities greener

Asphalt and concrete prevent water from penetrating. Where soil is unsealed, trees are planted and green spaces are designed to accommodate the changed climate conditions, more water is retained in the soil. Carefully designed green spaces also reduce temperatures in densely built-up neighborhoods. An example in this respect is the Telegrafenberg hill in the German city of Potsdam. In 2025, Drees & Sommer was entrusted by the GFZ Helmholtz Centre for Geosciences with the task of developing a comprehensive landscape plan for an area of 27 hectares. Studies showed that around 78 percent of the stand of trees was damaged by heat and draught.[x] The project focuses, inter alia, on the planting of climate-resilient trees which need less water than the existing trees. Many of them are older than 100 years. The aim is to stabilize the water balance of the campus in the long term.

Saving water in private households

Water butts, cisterns or water-saving fixtures can noticeably reduce water consumption. However, the key to guaranteeing a reliable water supply is investment in the water infrastructure, rainwater management and the reuse of water. These issues provide the largest potential for savings. Dr. Wasielewski pointed out: „The question is not whether water will become a location factor – it already is. The decisive thing is how soon cities and municipalities respond.”

Stuttgart, Germany, July 15, 2026.As meteorologists issue warnings in advance of the next heatwave, the dry conditions in many parts of Germany are intensifying. The water level on Lake Constance is significantly below normal. The river flow on the Danube is lower regionally than it has been in decades, and levels on the Rhine are also falling. Shipping companies, agriculture, industrial firms and water suppliers are under increasing pressure to use resources more efficiently. For cities, towns and villages, one question is becoming ever more pressing: how can water supply be safeguarded in long periods of drought? 

Since the end of June, the city of Stuttgart has severely restricted the withdrawal of water from streams, rivers or lakes in an effort to protect the aquatic environment against the stresses of high temperatures and low water levels.[i] Violations of the restrictions can result in fines of up to 100,000 euros. In its Master Plan for Public Water Supply, the Ministry for the Environment, Climate and Energy Sector of the federal state of Baden-Wuerttemberg projects that, under the current conditions, more than half of all municipalities in the state will be unable to meet peak drinking water demand by 2050.^[ii] The situation in the country as a whole is also stark: according to the GFZ Helmholtz Centre for Geosciences, at the end of 2025, Germany had already lost 25 billion cubic meters of its water volume compared with the long-term average.[iii] This is equivalent to more than half the water in Lake Constance.[iv] 

Dr. Stephan Wasielewski has been focusing on the impact of water scarcity, in both research and practice, for more than a decade. The graduate engineer in environmental sciences earned his doctorate at the University of Stuttgart. Today, he manages the water infrastructure area at Drees & Sommer. Prior to this, he collaborated in drafting the Water Supply Master Plan of the federal state of Baden-Wuerttemberg. He said: “In actual fact, we have enough water in Germany. However, the frequency with which water is getting to the wrong place at the wrong time is increasing. Long-lasting periods of drought alternate periods of intense rainfall. 

But sewer systems and surfaces often cannot cope with the volumes of water. The supply of water has long been about infrastructure and become a location factor.”

In the view of Drees & Sommer’s experts, water must be kept in circulation for longer, losses reduced and the use of available resources optimized:

1. Keeping rainwater where it falls

In many places rainwater is still being dealt with by getting rid of it as quickly as possible This is becoming a problem in times of increasing droughts. Infiltration areas, green roofs, troughs infiltration trench systems or cisterns ensure that rainwater is retained in the soil and improve groundwater reservoirs. Drees & Sommer’s project in Berlin’s Lichtenberg district demonstrates how this works in practice. The local roads and parks department commissioned Drees & Sommer SE to select 24 out of 90 schools for disconnection from the sewage system. In order to keep rainwater where it falls, instead of flowing into the sewage system, green spaces and infiltration areas with troughs and ditches will be created on a total sealed surface area of around 135,000 square meters (roughly the size of 19 soccer pitches).[v]

2. Reducing water losses in the system

Droughts are not the only thing costing money. Failing pipes also contribute to the loss of valuable drinking water: Around 319 million cubic meters of water is lost every year in Germany due to leaking pipes. This corresponds to the annual demand of almost seven million people.[vi] Digital leak detection, tight monitoring and refurbishment of old networks help municipalities to reduce the losses significantly. Since 2023, for example, the municipal utility Stadtwerke Bad Homburg has been collaborating with Preventio, a Frankfurt-based start-up company that uses in-house artificial intelligence (AI) technology to detect leaks at an early stage to prevent larger damage and water losses.[vii]

3. Reusing water

Many uses do not require drinking water. Rainwater, gray water and service water can be used for watering green spaces, flushing the toilets or technical installations, for example. This reduces the consumption of high-quality drinking water. “We need to move beyond the thoughtless system of withdrawal, use and discharge. Sustainable, future-proof regions will be those that reuse water several times and keep water in circulation – this has become a key location factor for businesses too," explains Dr. Stephan Wasielewski. Drees & Sommer is conducting research for Trostberg-based Alzchem Group into how service water from the central wastewater treatment plant can be reclaimed and reused repeatedly in its plants to reduce drinking water consumption of the chemical company.[viii]

4. Managing water withdrawal transparently

When water becomes more scarce, competition among users is heightened. Agriculture, industry, energy supply and municipalities use the same resources. In many cases the parties involved do not know who consumes, when, how much. Digital water registries create transparency regarding withdrawal rights, protected areas and actual water withdrawals.[ix] For instance, the federal state of Rhineland-Palatinate has maintained a fully digital water registry since 2004; other states are still working on creating one. Municipalities and water authorities can access real-time data, identify scarcities at an early stage and respond in a targeted way instead of imposing blanket restrictions across all user groups.

5. Unsealing urban soil and making cities greener

Asphalt and concrete prevent water from penetrating. Where soil is unsealed, trees are planted and green spaces are designed to accommodate the changed climate conditions, more water is retained in the soil. Carefully designed green spaces also reduce temperatures in densely built-up neighborhoods. An example in this respect is the Telegrafenberg hill in the German city of Potsdam. In 2025, Drees & Sommer was entrusted by the GFZ Helmholtz Centre for Geosciences with the task of developing a comprehensive landscape plan for an area of 27 hectares. Studies showed that around 78 percent of the stand of trees was damaged by heat and draught.[x] The project focuses, inter alia, on the planting of climate-resilient trees which need less water than the existing trees. Many of them are older than 100 years. The aim is to stabilize the water balance of the campus in the long term.

Saving water in private households

Water butts, cisterns or water-saving fixtures can noticeably reduce water consumption. However, the key to guaranteeing a reliable water supply is investment in the water infrastructure, rainwater management and the reuse of water. These issues provide the largest potential for savings. Dr. Wasielewski pointed out: „The question is not whether water will become a location factor – it already is. The decisive thing is how soon cities and municipalities respond.”

Stuttgart, Germany, July 15, 2026.As meteorologists issue warnings in advance of the next heatwave, the dry conditions in many parts of Germany are intensifying. The water level on Lake Constance is significantly below normal. The river flow on the Danube is lower regionally than it has been in decades, and levels on the Rhine are also falling. Shipping companies, agriculture, industrial firms and water suppliers are under increasing pressure to use resources more efficiently. For cities, towns and villages, one question is becoming ever more pressing: how can water supply be safeguarded in long periods of drought? 

Since the end of June, the city of Stuttgart has severely restricted the withdrawal of water from streams, rivers or lakes in an effort to protect the aquatic environment against the stresses of high temperatures and low water levels.[i] Violations of the restrictions can result in fines of up to 100,000 euros. In its Master Plan for Public Water Supply, the Ministry for the Environment, Climate and Energy Sector of the federal state of Baden-Wuerttemberg projects that, under the current conditions, more than half of all municipalities in the state will be unable to meet peak drinking water demand by 2050.^[ii] The situation in the country as a whole is also stark: according to the GFZ Helmholtz Centre for Geosciences, at the end of 2025, Germany had already lost 25 billion cubic meters of its water volume compared with the long-term average.[iii] This is equivalent to more than half the water in Lake Constance.[iv] 

Dr. Stephan Wasielewski has been focusing on the impact of water scarcity, in both research and practice, for more than a decade. The graduate engineer in environmental sciences earned his doctorate at the University of Stuttgart. Today, he manages the water infrastructure area at Drees & Sommer. Prior to this, he collaborated in drafting the Water Supply Master Plan of the federal state of Baden-Wuerttemberg. He said: “In actual fact, we have enough water in Germany. However, the frequency with which water is getting to the wrong place at the wrong time is increasing. Long-lasting periods of drought alternate periods of intense rainfall. 

But sewer systems and surfaces often cannot cope with the volumes of water. The supply of water has long been about infrastructure and become a location factor.”

In the view of Drees & Sommer’s experts, water must be kept in circulation for longer, losses reduced and the use of available resources optimized:

1. Keeping rainwater where it falls

In many places rainwater is still being dealt with by getting rid of it as quickly as possible This is becoming a problem in times of increasing droughts. Infiltration areas, green roofs, troughs infiltration trench systems or cisterns ensure that rainwater is retained in the soil and improve groundwater reservoirs. Drees & Sommer’s project in Berlin’s Lichtenberg district demonstrates how this works in practice. The local roads and parks department commissioned Drees & Sommer SE to select 24 out of 90 schools for disconnection from the sewage system. In order to keep rainwater where it falls, instead of flowing into the sewage system, green spaces and infiltration areas with troughs and ditches will be created on a total sealed surface area of around 135,000 square meters (roughly the size of 19 soccer pitches).[v]

2. Reducing water losses in the system

Droughts are not the only thing costing money. Failing pipes also contribute to the loss of valuable drinking water: Around 319 million cubic meters of water is lost every year in Germany due to leaking pipes. This corresponds to the annual demand of almost seven million people.[vi] Digital leak detection, tight monitoring and refurbishment of old networks help municipalities to reduce the losses significantly. Since 2023, for example, the municipal utility Stadtwerke Bad Homburg has been collaborating with Preventio, a Frankfurt-based start-up company that uses in-house artificial intelligence (AI) technology to detect leaks at an early stage to prevent larger damage and water losses.[vii]

3. Reusing water

Many uses do not require drinking water. Rainwater, gray water and service water can be used for watering green spaces, flushing the toilets or technical installations, for example. This reduces the consumption of high-quality drinking water. “We need to move beyond the thoughtless system of withdrawal, use and discharge. Sustainable, future-proof regions will be those that reuse water several times and keep water in circulation – this has become a key location factor for businesses too," explains Dr. Stephan Wasielewski. Drees & Sommer is conducting research for Trostberg-based Alzchem Group into how service water from the central wastewater treatment plant can be reclaimed and reused repeatedly in its plants to reduce drinking water consumption of the chemical company.[viii]

4. Managing water withdrawal transparently

When water becomes more scarce, competition among users is heightened. Agriculture, industry, energy supply and municipalities use the same resources. In many cases the parties involved do not know who consumes, when, how much. Digital water registries create transparency regarding withdrawal rights, protected areas and actual water withdrawals.[ix] For instance, the federal state of Rhineland-Palatinate has maintained a fully digital water registry since 2004; other states are still working on creating one. Municipalities and water authorities can access real-time data, identify scarcities at an early stage and respond in a targeted way instead of imposing blanket restrictions across all user groups.

5. Unsealing urban soil and making cities greener

Asphalt and concrete prevent water from penetrating. Where soil is unsealed, trees are planted and green spaces are designed to accommodate the changed climate conditions, more water is retained in the soil. Carefully designed green spaces also reduce temperatures in densely built-up neighborhoods. An example in this respect is the Telegrafenberg hill in the German city of Potsdam. In 2025, Drees & Sommer was entrusted by the GFZ Helmholtz Centre for Geosciences with the task of developing a comprehensive landscape plan for an area of 27 hectares. Studies showed that around 78 percent of the stand of trees was damaged by heat and draught.[x] The project focuses, inter alia, on the planting of climate-resilient trees which need less water than the existing trees. Many of them are older than 100 years. The aim is to stabilize the water balance of the campus in the long term.

Saving water in private households

Water butts, cisterns or water-saving fixtures can noticeably reduce water consumption. However, the key to guaranteeing a reliable water supply is investment in the water infrastructure, rainwater management and the reuse of water. These issues provide the largest potential for savings. Dr. Wasielewski pointed out: „The question is not whether water will become a location factor – it already is. The decisive thing is how soon cities and municipalities respond.”