Euroregion Baltic

Introduced in 2009, the EU Strategy for the Baltic Sea Region (EUSBSR) was the first EU macro-regional strategy of the European Union. Formally adopted by the European Council after a communique from the European Commission (EC), the EUSBSR is an agreement signed between the Member States and the EC to strengthen cooperation between the countries bordering the Baltic Sea and to meet the many joint challenges as well as benefit from common opportunities facing the Baltic Sea region through three objectives: Save the Sea, Connect the Region and Increase Prosperity.

The Umbrella 2.0 project has been developed precisely to make the EUSBSR more “user-friendly” for the local stakeholders. The Umbrella 2.0 project was initiated by the Euroregion Baltic (ERB) and is implemented throughout 2021 with two partners: Union of the Baltic Cities (UBC) and Baltic Sea States Subregional Cooperation (BSSSC). This project is funded by the Swedish Institute, which has supported Baltic Sea cooperation for many years, especially among the local actors. The project also builds on two previous capacity building projects successfully implemented by the Euroregion Baltic and its Partners within the Interreg South Baltic Programme.

Over the course of two months, the experts conducted a series of 14 interviews with Coordinators of all Policy Areas of the Strategy, attempting on the one hand to gain a broad picture of the current status of local stakeholders’ participation but also to listen to interesting ideas and proposals on what should be done further to integrate them in the works of the Strategy. To this end, we asked several questions through which we have received a great deal of interesting feedback and some concrete proposals for the future of the EUSBSR implementation.

The resulting report is directed both towards the local stakeholders who are newcomers to the Strategy as well as those local actors who are more experienced in Baltic cooperation but would like to organise their knowledge and understanding of how the Strategy can be of use for them. Lastly, we hope that this report will help all institutions directly or indirectly involved in implementing the EUSBSR to learn more about the importance of improved collaboration with the local level of governance to achieve the goals outlined in the Strategy.

Download the Umbrella 2.0 report here:

Umbrella 2.0 report Entry points to EUSBSR cooperation Download

About the ERB Water Core Group

WCG Work Plan 2020-2022

ERB WCG workplan_ 2020-2022 Download

List of ERB WCG members: https://www.eurobalt.org/category/water-core-group-board/

On 28 October 2025, the first General Assembly of the Euroregion Baltic in its new formal structure as a European Grouping of Territorial Cooperation (EGTC) was held in Gdańsk.

The meeting was chaired by Mr. Leszek Bonna, Deputy Marshal of the Pomorskie Voivodeship, and marked a significant step in strengthening cross-border cooperation across the Baltic Sea region.

The establishment of the EGTC opens a new chapter for Euroregion Baltic — creating a solid framework for coordinated activities, joint projects, and long-term regional development efforts.

With this new structure in place, member regions are now better equipped to:

enhance cooperation between local and regional authorities,
implement strategic initiatives more efficiently,
foster sustainable development throughout the Baltic Sea area.

The General Assembly highlighted the shared commitment of all members to building a more integrated, resilient, and forward-looking Baltic Sea Region.

Bornholm has used a feasibility study to examine a question that could turn the entire Baltic Sea Region into a major player in renewable energy: Could recycled water be used to produce the hydrogen needed to store wind energy? The answer is yes – and it is significantly more cost-effective than using desalinated seawater. But the right conditions have to be in place.

Large offshore wind farms are being built around Bornholm and plans for the island as an energy hub are taking shape. But electrolysis, the process used to generate green hydrogen as a storage medium for wind energy, requires enormous volumes of highly purified water, known as ultra-pure water (UPW). Ever since Bornholm set out its vision of becoming an “energy island,” the question has been on the table: Where will this essential resource for hydrogen production come from? This question is especially relevant because Bornholm, like many coastal regions around the Baltic Sea, is humid but not free from water scarcity. The island extracts around three million cubic metres of drinking water from groundwater each year – a resource that already comes under strain during the summer months, when visitor numbers on the tourist island peak. Climate projections indicate that availability will not improve. Using significant amounts of groundwater for industrial electrolysis would therefore be both ecologically and ethically problematic. So the next obvious source to consider is seawater – of which there is certainly no shortage here.

These were, in very brief terms, the first considerations that ultimately led Bornholm to rethink its approach to water management – and eventually to carry out an initial feasibility study. It examines the question: Should the water required for the planned hydrogen production really come from desalinated seawater, or would it be better to recycle municipal wastewater instead? Both options are technically feasible. Seawater is nominally unlimited, but desalination is energy-intensive and expensive. Treated municipal wastewater, on the other hand, is a continuously available resource located close to the point of demand.

Until now, wastewater recycling has generally been considered relatively expensive – at least when it comes to producing drinking water. But with regard to the planned hydrogen production, the feasibility study assumed that wastewater recycling could be highly advantageous both ecologically and economically, provided the entire life cycle and local conditions were taken into account. And this assumption was confirmed.

Municipal Foresight: Wastewater Becomes a Resource

“Our life-cycle analysis showed that treated wastewater can reduce energy consumption and the CO₂ footprint by up to 44 percent compared with seawater desalination,” explains Paulo Silva, the study’s project manager at the municipal water supplier BEOF. “Of course, this effect only applies if wind power is used for wastewater recycling. But those synergies exist here on Bornholm.” The analysis outlines supply pathways for both a 25 MW electrolyser and a large-scale 800 MW scenario. In both cases, treated wastewater can reliably provide the required volumes of water.

That such a study was initiated at all is remarkable – not least because of how it came about: it was not an industrial company but the municipal water supplier BEOF that launched it, an integrated public utility whose primary task is to supply drinking water to the population. “Bornholm’s drinking water resources are limited. Using them for industrial processes like electrolysis would not only be risky but ethically questionable,” says Silva. “With the study, we wanted to show that sustainable alternatives exist — and that municipal actors can take responsibility at an early stage.” The aim, he says, is to create a solution based on the use of treated wastewater that meets environmental standards, is economically viable, and protects drinking water resources.

Political Room for Manoeuvre and Technical Clarity

Technically, many things would be possible. But the study also shows that political decisions must provide the framework. The construction of a central wastewater treatment plant that could supply high-quality effluent on a larger scale was unfortunately postponed during the timeframe of the feasibility study. Until now, the 588‑square‑kilometre island has had 12 small and medium-sized wastewater treatment plants that treat municipal wastewater locally before returning it to the natural cycle. The large central treatment plant, initially envisioned for Rønne or a more central inland location, would have provided a major efficiency gain for hydrogen production. In the feasibility study’s economic calculations, it functioned almost like an extra booster. For a brief moment, it seemed as if the booster could materialise sooner than expected. When local political priorities changed, however, the plans reverted to the original, longer-term schedule.

It will be interesting to see how things develop over the coming years. But even with decentralised treatment plants, recycling wastewater for hydrogen production would be viable. “The feasibility study takes a long-term perspective anyway, and municipal planning processes sometimes move slowly. That is precisely why the study is so important,” says Silva. “It provides robust data on which political decisions can be based – and at the same time raises the question of what role municipal companies should play in these developments.” As the municipal utility, BEOF does not see itself as the operator of a hydrogen plant, but as an enabler: a provider of fit-for-purpose water for industrial use produced from circularly reused wastewater. The responsibility for the final purification into ultra-pure water lies with the PtX operator. However, under Danish law, a municipal supplier is not permitted to deliver industrial process water below drinking water quality directly. BEOF is therefore considering establishing a sister company exclusively responsible for industrial water needs. Such an organisationally separate structure would guarantee legal clarity and protect the public drinking water supply.

Legal Certainty Through New Structures

“We absolutely do not want to hinder industrial development – but it must be sustainable,” emphasises Silva. “By establishing a separate water system for industrial purposes, we can open doors without putting the population’s water security at risk.”

The study also does not shy away from critical aspects. A particularly critical issue is the handling of the saline waste stream, the concentrated salt residues that result from reverse osmosis during water purification (the so-called RO brine). In the large-scale scenario (800 MW), the volume of RO brine could amount to as much as 25 percent of the wastewater treatment plant’s inflow – an environmental burden that cannot simply be discharged into the Baltic Sea. A functioning concept for treating this brine is therefore essential. The study recommends piloting under real conditions to test practical feasibility, purification performance, and regulatory compliance before significant investments are made. Logistical and permitting issues also remain to be clarified: ideally, a wastewater treatment plant would be built close to the PtX facility, but available land is scarce. Currently, the scenario is based on using the existing facility in Rønne and transporting the water to the planned PtX site near the substation.

A Model for the Entire Baltic Sea Region

These questions relate not least to Bornholm’s specific local conditions. Yet the broader significance of the project is already clear. Across many parts of the Baltic Sea Region – from Sweden to Poland and northern Germany – plans for green hydrogen production are emerging. And everywhere, the same question arises: Where will the ultra-pure water come from? Bornholm is setting an example by having municipal actors strategically consider how resource protection and industrial development can be brought together – and how wastewater recycling can become a key factor in the green transition.

Bornholm illustrates a challenge shared by many coastal regions around the Baltic Sea: being located in a humid climate does not automatically guarantee secure water availability. Around three million cubic metres of drinking water are extracted from the groundwater each year; total available water resources are estimated at around five million cubic metres annually. Against this backdrop, allocating significant amounts of groundwater for industrial electrolysis would be problematic in many regions – both ecologically and ethically. The water demand of hydrogen production is not a minor issue. It is a central lever for achieving climate goals while protecting scarce resources. Bornholm has demonstrated how to approach this question systematically and provides a toolkit for other regions that wish to take similar steps. “Drinking water extracted from groundwater is reserved for the population. Industry receives fit‑for‑purpose water from alternative sources – that is the clear line,” says Silva, referring to Bornholm’s “Wastewater as a Resource” strategy.

Knowledge Creates Room for Action

Feasibility studies like the one carried out on Bornholm are not mere theoretical exercises. They are tools for informed decision-making and help create political scope for action. Above all, they show that sustainability always requires organisation, responsibility and the willingness to think ahead.

The planned centralisation of municipal wastewater treatment would create a reliable, high-quality source for water recycling – and the hope is that the necessary investments will soon be approved. The feasibility study now puts this vision on a firm footing: it quantifies technical options, costs and environmental impacts and translates them into concrete scenarios. In doing so, it supports decisions that can serve as a model far beyond Bornholm. As a result, the island has not only delivered a technical answer to the water question, but also a clear signal of what becomes possible when local actors take the lead in the energy transition.

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About the “WaterMan” project

Due to climate change, periods of drought are becoming more frequent in the Baltic Sea Region and drinking water, which is mainly obtained from groundwater here, can get scarce in certain periods. For that reason it will be necessary to use water of different qualities and to tap into other sources of “usable water” in the future. “WaterMan” supports municipalities and water companies in adapting their strategies. A region-specific approach to water recycling uses the alternation of too much and too little water, which has become typical in the Baltic Sea Region, to make the local water supply more resilient.

More information: interreg-baltic.eu/project/waterman/

In the Swedish municipality of Västervik, the initially simple idea of building rainwater retention ponds has evolved into the concept of “Mini Multi-dams”: making rainwater directly usable and creating many small basins wherever there are users for the water. This is because groundwater is at times scarce in this region, and such periods are becoming more frequent, while stormwater is not.

In Västervik, a coastal town of around 36,000 inhabitants at the southern end of the Swedish archipelago, people are rethinking water management. They are doing so with an instrument that appears quite unspectacular at first glance: retention ponds. As structures to mitigate the destructive power of stormwater, which has always been abundant around the Baltic Sea, especially in winter, and is becoming even more so due to climate change, such ponds can be found in many places around the region. They have proved their worth in relieving sewer systems and preventing floods, and in protecting biodiversity and reducing nutrient loads before water is discharged into the sea.

In Västervik, however, something fundamental has changed in recent years. The key lies in a shift of perspective: why not make direct use of the stored water before it turns into groundwater? If rainwater is naturally pre-treated within a pond ecosystem and then distributed in a targeted way, it becomes an additional pillar of the local water supply – for example, to produce artificial snow for cross-country ski trails, or to irrigate sports fields, parks and cemeteries. In other words: water for the future.

Climate change has accelerated the shift in thinking

The challenges Västervik faces in the wake of climate change have also encouraged this shift in thinking. Heavy rainfall events and flooding have become more frequent, while in summer new weather patterns have emerged that were previously unknown in the area: extended dry periods that sometimes lead to water scarcity. Compounding the problem, the soil around Västervik is hard and absorbs water only slowly. Because of the geological structure of the subsurface, the region only has a small groundwater body to begin with. In recent years, the authorities have repeatedly had to temporarily prohibit residents from watering gardens with tap water. In short, the municipality had many reasons not to see the increasing oscillation between “too much” and “too little” water merely as a rising problem – but to recognise it as an opportunity.

As part of this rethinking, traditional retention ponds became “Multi-dams”. The word “Multi” initially referred to the idea that these basins would have an additional purpose: they are designed with tap points that allow water to be extracted and used. By developing conventional retention ponds into multifunctional sources of usable water, Multi-dams can become a stabilising element in the local water supply.

In the Gamleby district, the first Multi-dam went into operation as early as 2020. This multi-purpose pond collects surface runoff from a catchment area of around 80 hectares, reduces flood peaks and at the same time provides water for nearby users. The opportunity to access water that was, at least initially, still free of charge did not go unnoticed. More and more users began to draw on it – from sports clubs with large grass pitches to private households with sizeable gardens.

Moving quickly from talk to action – and learning fast

However, that was not the end of the story. The further development of the Multi-dam concept within the WaterMan project has made something else almost textbook-clear: when it comes to water recycling, concrete, pragmatic measures can generate valuable insights very quickly. Anyone who moves swiftly from talking to doing often experiences a steep learning curve. In Gamleby, the first experiences revealed that the main challenge is not collecting the water, but transporting it to potential users. Long pipelines and numerous trips with tanker trucks are labour-intensive, costly and inflexible.

In the past, retention ponds in the Baltic Sea Region were usually built where it made most sense to intercept stormwater and prevent damage. Because water scarcity was not yet seen as a major issue, they were not planned with a view to where there might be high demand for recycled water. A paradigm shift was needed – and Västervik has consistently put it into practice. Instead of constructing a few large retention ponds, the municipality now focuses on many small “Mini Multi-dams” – each one located where water is needed: close to commercial areas, sports facilities, parks and residential neighbourhoods.

Anders Fröberg, project manager at Västervik Municipality, has been one of the driving forces behind this shift. “If the distance is small, a short pipeline is often enough. Otherwise, trailers have to transport the water to where it is needed,” he explains. The result of this close-range solution: lower costs, greater flexibility – and less use of drinking water. “Being right at the source means things are simpler, cheaper and more sustainable,” adds Fröberg.

The real innovation: decentralising the retention ponds

Success has had a knock-on effect: one solution became many, and one central storage point evolved into a decentralised strategy. In new development areas such as Åbyhöjden, rainwater is now even used for toilet flushing once it has been qualified as “technical water” – a common term in Sweden for usable water that does not meet drinking water quality. This saves groundwater and clearly demonstrates that many applications do not require drinking water quality. The real innovation lies in this decentralisation: it makes the system both more cost-effective and more adaptable. And the word “Multi-dams” gains another layer of meaning. Fröberg sums up the approach as follows: “We combine the two sides of the same coin – ‘too much’ and ‘too little’ water – and turn them into water security by building many small Multi-dams.”

The city has since been in close contact with sports clubs, housing associations, park maintenance teams and private individuals. Anyone who needs water is included in the planning. And anyone who uses it is supported – through training sessions, feedback meetings and information materials.

Six Multi-dams have already been built in Västervik, four more are in advanced planning, and around ten additional “Mini Multi” locations are being developed for the longer term. With each new facility, a decentralised network of storage points grows, bringing rain back into everyday life as a resource. Sports facilities are particularly active in seeking access, as they have high water demand and benefit directly. Dialogue with urban planning is crucial in this context. In future land-use plans, Multi-dams are to be integrated at an early stage, as part of the municipal infrastructure.

The task ahead: developing a business case

The question of where the rainwater comes from is becoming all the more important. Water that runs off heavily trafficked roads or industrial sites is only used in exceptional cases and only after strict testing. According to project manager Anders Fröberg, the Multi-dam in Gamleby meets all the requirements for microbiological safety. Other locations make additional use of wetlands or biochar filters to further treat the water alongside natural sedimentation. Natural treatment is an integral part of the solution: no chemical additives, no complex machinery, but nature-based solutions. “The water in the upper parts of the catchment area is simply cleaner. If we retain it there, we can start with simple, low-cost solutions,” explains Fröberg. For additional “next generation” sites, light disinfection stages (such as UV) have also been evaluated to enable a broader range of applications, for example for washing vehicle fleets. That option is there for the future. For now, however, straightforward uses such as irrigating public green spaces or private gardens already go a long way towards saving drinking water.

As yet, Sweden has no official guidelines for the use of decentralised rainwater. But Västervik is setting practical standards that show: it is possible without excessive bureaucracy when political will, technical know-how and pragmatism come together.

In this context, the question of pricing recycled rainwater from Multi-dams is still entirely open. Until now, the water has been provided free of charge. In the future, according to the current state of debate, moderate fees, pooling the demand of several end users, and special offers for local businesses could help to finance the maintenance and expansion of the Multi-dam network. A business case will have to be developed. But for that to happen, municipalities and public utilities in Sweden must first be given a legal basis to charge varying prices for different water qualities.

Multifunctional tools for water resilience in the Baltic Sea Region

What already makes the system compelling today is its high transferability. Retention ponds are widely known across the Baltic Sea Region, but so far they have mainly been used for flood control or biodiversity. The potential to tap them as sources of fit-for-purpose water where drinking water quality is not required is enormous and, in many places, still largely unused.

Västervik offers a blueprint here, showing how the classic flood control instrument of stromwater retention ponds can be turned into a flexible, adaptable and highly practical approach to local water recycling. Multi-dams as multifunctional tools for water resilience in the Baltic Sea Region.

Start with sports fields and lead by example

Fröberg’s advice to other municipalities that want to get started is equally pragmatic: “Begin with sports fields. That’s where demand is high, acceptance is usually strong and the impact quickly becomes visible to many people.” It also helps when municipalities lead by example – for instance by irrigating young trees and summer flowers with recycled water – while actively supporting pioneering private users and showcasing good examples publicly. This way, people begin to understand that rainwater is a local resource – not an unwanted surplus to be disposed of as quickly as possible.

In Västervik, the question is no longer if water should be recycled, but how. With the concept of “Mini Multi-dams”, the municipality has found a convincing answer: store rainwater where it is needed and turn a problem into a resource.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

In Saldus in Latvia, the simple wish for a fountain in the town centre has grown into a holistic concept that combines flood protection and water recycling with an upgrade of public space. The end result is a feasibility study ready for implementation – not only in Saldus, but potentially in many other places across the Baltic Sea Region.

Anyone strolling through Saldus without expert knowledge would not suspect how closely urban design and the demands of water management are intertwined here. The central square, some historic buildings, lively paths in between, small cafés and people meeting one another – all very pleasant, but at first glance just a small town like many others. Experts, however, quickly recognise the vulnerable points. In terms of its topography, Saldus has the shape of a natural bowl. As soon as it rains heavily, water rushes down from the slopes across the main square, Kalpaka laukums, into the lower parts of the town. Within a very short time, it floods streets, pours into basements and creates emergency situations for residents and local authorities. And the outlook is not encouraging: with heavy rainfall events becoming more frequent due to climate change, such situations are likely to occur more often and become even more severe.

Over the past three years, Saldus has set out to turn these challenges into opportunities. To begin with, the thinking was by no means as comprehensive as it is today. Everything started with ideas for beautifying the town. The mayor had long had the wish to enhance Kalpaka laukums with a central fountain. It was intended not just as a design element for the townscape, but as a real contribution to the attractiveness of the town centre as a place to spend time. The fountain, together with new greenery, was to create a place of encounter where children could play in the water on hot days. Up to this point, the project was simply a classic urban development measure.

A flow of future-oriented ideas

What brought about a flow of additional, future-oriented ideas was the close cooperation between the municipality of Saldus and the Kurzeme Planning Region – and their joint participation in the WaterMan project. This opened up a completely new set of questions: why not turn the planned fountain at this vulnerable point in Saldus into the anchor of a modern, forward-looking water management approach?

Such a plan would be an opportunity to address several challenges Saldus will face in the near and more distant future at once. The increase in flooding caused by more frequent heavy rainfall under climate change is only one part of the problem. In the medium to long term, climate data suggest that this region, too, will see more frequent dry spells and periods of water scarcity. On top of that, Saldus is confronted with a challenge that almost all small and medium-sized towns face today: to keep residents and attract new ones, they need to make themselves more attractive – for example by creating inviting public spaces where people enjoy spending time.

“In Latvia, water recycling has so far not been high on the political agenda; groundwater and surface water have generally been sufficient,” says Jānis Blūms, project manager at the municipal utility. “But in the future, it will be our task to manage and balance the shift between too much and too little water at local level. That means storage, simple, low-maintenance technology – and a willingness to stop thinking of all urban water use exclusively in terms of drinking water.”

Making water recycling tangible in an emotionally charged place

Based on these reflections, the first plans emerged for a “three-in-one” system. Rainwater that had previously flowed uncontrolled down the slope into the town was to be captured and buffered. An underground retention reservoir would absorb the surface runoff before it can cause damage. After that, the stored water could be used for irrigating green spaces or street cleaning, following UV disinfection. And of course, it would also feed the planned fountain, turning it into a powerful symbol of sustainable resource use at the heart of the town.

What Saldus has conceived here is remarkable, not least because it breaks with long-standing reflexes in urban development. A comparatively short-term political impulse was used to develop a holistic concept that goes far beyond what is visible. The fountain is not merely decorative; it is a functional part of a system that captures, stores, treats and uses rainwater multiple times. In this way, water recycling is made visible and tangible in an emotionally charged place.

At the same time, technical necessity and an upgraded public space are combined with education about a new form of water management for the Baltic Sea Region in times of climate change. The fountain becomes a teaching tool and showcase: instead of using drinking water for everything, it demonstrates a fit-for-purpose approach – using water in exactly the quality that matches the specific use.

Blūms stresses: “We want to show that water recycling is not an abstract technology, but something that works in a concrete, visible and everyday way – right in the central square of our town.”

A small setback becomes a catalyst

A few key facts and figures: technically, the concept envisages an underground retention tank with a volume of 90 m³, plus a multi-stage filtration system including UV disinfection and a monitoring system that records storage levels, water quality and water use in real time. A digital information screen on the square will explain the functioning of the system and display the main figures in real time. How much water is currently stored? What can it be used for? How much drinking water is being saved?

This makes integrated water management something people can grasp in very practical terms. “If you want people to become aware of a problem and support a solution, you have to make things transparent,” says Eva Jēkobsone, who has overseen the project for the municipal administration.

Everything was looking very promising, and it seemed that construction would soon begin. But then came a setback: when the concept went out to tender, the projected costs turned out to be significantly higher than the original budget. The main cost driver was the ambitious size and depth of the underground reservoir. Faced with this, the city council decided to put the project on hold. It was a critical moment – the kind that often brings promising ideas to a halt.

In Saldus, however, where the project had already gathered considerable momentum, this setback became a catalyst. Instead of abandoning the plans, the team chose to further develop and refine them. The concept was completed as an implementation-ready feasibility study – including additional potential applications for the treated water. “The project will not be implemented in the coming months, but it is ready,” explains Blūms. “We assume that implementation will take place in stages, depending on funding and political priorities.”

Sometimes willingness to learn is more valuable than prior knowledge

In refining and detailing the concept, the team also benefited from peer learning with the partner regions in the WaterMan project. Because water scarcity has not traditionally been a major issue in Latvia, the Saldus team initially had little experience with water recycling – let alone with combining retention, recycling and redesign of public space.

Instead of being discouraged by the temporary halt to the project, they continued to focus firmly on peer learning. Exchanges within the WaterMan partnership, particularly with the colleagues in Kalmar, Västervik and Gargždai, provided crucial impulses. Klaipėda University, Gdańsk University of Technology and the Berlin Centre of Competence for Water (KWB) contributed scientific expertise, shared studies, planning tools and practical experience.

“Sometimes the willingness to learn is more valuable than any amount of prior knowledge,” says Jānis Blūms. “We have benefited from simple, proven solutions. Now we are equally happy to share our experience.”

“From our point of view, it was in no way a disadvantage that the concept developed here would be significantly more expensive to realise than originally planned,” stresses WaterMan project coordinator Jens Masuch. The complexity of the solution, he argues, is not a weakness but a strength. The result is a technically well-thought-through, implementation-ready concept that brings together flood protection and water recycling in a targeted way. In other words: it is precisely the kind of solution that can build climate resilience in the face of increasingly extreme shifts between too much and too little water in the Baltic Sea Region. For this reason, the concept is highly valuable for many other places as well, which can use it practically as a blueprint. “Saldus and its feasibility study are, in a way, water recycling for the Baltic Sea Region in a nutshell,” says Masuch. This also includes safeguarding “nice-to-have” features such as fountains and green spaces for the future – by systematically integrating them into water management solutions.

What to do with winter water?

Nevertheless, there were still points and details that needed further clarification. This also became apparent in discussions at WaterMan partner meetings. What are realistic assumptions regarding maintenance requirements and costs? Where is the full set-up worthwhile, and where would a leaner configuration be more appropriate? And what should be done with the rainwater collected in winter, when the fountain is not in operation?

The answer was pragmatic: it could be used the following spring for street cleaning. “The reservoir will be built below the frost line,” explains Blūms. “The water can easily remain there over winter. Once it is needed, it will be available.” When the basin is full, an overflow will ensure that excess rainwater is discharged in a controlled manner into the sewer system. Even this eventuality is already built into the developed solution.

Water quality was naturally another key issue and raised detailed questions. Since the fountain is publicly accessible and children are expected to play in the water, high standards of hygiene must be applied. Blūms emphasises: “The water quality should match that of inland waters suitable for bathing.” To achieve this, the system is designed to undergo regular disinfection and continuous monitoring of relevant parameters. The planned information screen is intended not only to explain the system, but also to display current water quality data. This is meant to provide yet another example of the meaningful interplay between technology and transparent communication.

The first dry summer will surely come

Wherever such a system is built first, it will be far more than just an attractive water feature. It represents a shift in the way we think about water management in the Baltic Sea Region – the recognition that even in previously water-rich regions such as Latvia, the anticipated effects of climate change mean that prevention is better than cure. Design or disaster. Or, as Eva Jēkobsone puts it: “The first dry summer will surely come. Then people will remember Saldus.”

Here, the foundations have been laid for a solution that, if implemented, would also noticeably enhance the quality of life in the town. But the fountain was only the starting point. Through persistent work and constructive collaboration, it has evolved into a rich source of ideas for an integrated water management approach – all of which has flowed into a feasibility study that is now ready for practical implementation. Perhaps Saldus will be the first to make use of it. In any case, the search for additional funding is already under way there.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

At first, the retention basin in Gargždai was planned with a single purpose in mind: preventing floods. But long-term climate projections suggest that Lithuania, too, will not only face more intense rainfall, but also longer dry periods. So the planners decided to think a step ahead and ask how the stored water could be used – and in doing so, they turned the town into a national pioneer in water recycling.

Lithuania is not a dry country, and water is not a scarce resource here – at least not yet. Anyone driving through the green summer landscape around the town of Gargždai, near Klaipėda, can see that immediately. So why even start talking about water recycling here in the Baltics? The answer lies in a rather inconspicuous earth embankment on the edge of town. Behind it stretches a new body of water fringed with reeds: a retention basin built for flood control – but designed to do far more.

The starting point for the pilot measure could be called quite conventional. The municipality of Gargždai was struggling more and more with incidents of flooding. Climate change was already making itself felt in the form of frequent heavy rainfall, and the mixed-use sewer system dating from Soviet times was often overloaded. A retention pond was intended to cut peak loads and ensure that water could be discharged in a controlled way. This also became the starting point for Gargždai’s participation in the WaterMan project, which focuses on new approaches to water management in the Baltic Sea Region under climate change.

However, the collaboration that followed between the municipality, Klaipėda University and the association “Klaipeda Region” soon broadened the perspective. Professor Valdas Langas and his team asked a crucial question: if the long-term climate data already indicate an increase in drought periods in our region, why not address this development and design the retention pond from the outset in such a way that water can be extracted and used?

In Lithuania, this made Langas and his team pioneers

It was this forward-looking shift in perspective that turned a retention pond project, initially focused mainly on flood control, into a pioneering initiative. At least on a national level, Langas and his team were now leading the way. Because water had never really been scarce in Lithuania, the topic of water recycling had attracted little attention so far. This was now about to change. “We didn’t just want to drain the water away; we wanted to treat it as a resource – to make it usable,” explains Langas.

The idea was to create a multifunctional basin that would both protect against flooding and provide an alternative source of water, for instance for cleaning sewers, as a reserve for firefighting, and for irrigating parks and urban trees. The latter alone currently use around 300 m³ of drinking water per year, obtained from groundwater – the equivalent of about 1,500 filled bathtubs. In rainy Lithuania, that figure may not seem dramatic at first, but it is avoidable. And in view of increasing summer droughts around the Baltic Sea, avoiding this consumption may also become much more urgent in Lithuania in just a few years’ time. Langas and his team made sure that, by then, Lithuania will not have to start from scratch.

Pioneering work – above all in the legal framework

When it came to the construction of the pond and the technical implementation of water recycling, the team could draw, among other things, on the experience of WaterMan partners in Västervik in Sweden, who have been building “multi-dams” with water extraction options for years. Close professional exchange was also invaluable regarding monitoring strategies, testing parameters and operational issues.

Where the retention pond in Gargždai truly broke new ground was in terms of the legal framework in Lithuania. “Water recycling has not yet been formally anchored in Lithuanian legislation,” says Mindaugas Šatkus, who oversaw the project for the municipality together with his colleague Feliksas Žemgulys. Before the first excavator could move in, the two of them had to create a legal foundation. “There were some fundamental questions that had to be clarified – legally, technically and organisationally,” adds Langas.

EU Regulation (EU) 2020/741 does apply in Lithuania to agriculture and municipal wastewater, but how it should be applied to rainwater and municipal non-agricultural uses is not yet defined. For Gargždai, this meant many discussions, a lot of awareness-raising, and the courage to be the first municipality to build practical experience. Thanks to Mindaugas and Feliksas, the groundwork was completed quickly – and soon the excavators could roll in.

A textbook example of nature-based rainwater treatment

Since early 2025, the new retention pond has been in place. It is located in a well-used area near a football pitch and the Jewish cemetery, right in the middle of a popular local recreation zone. Its design follows the textbook principles of nature-based rainwater treatment: the main basin is preceded by a sedimentation forebay.

This is one of the features distinguishing the pilot measure in Gargždai from the multi-dams in Västervik. Valdas and his team deliberately opted for two-stage sedimentation: first, coarse particles settle; then finer fractions are removed in the lower section, where aquatic plants and microbial communities continue the treatment. Known as “treatment by design” – this is a process that works without energy-hungry technology. For planning and operation, the team used international SuDS (Sustainable Drainage Systems) standards as guidance. This reduces maintenance needs, stabilises the local ecology and makes future use more reliable. “We learned a great deal from others – and intentionally chose alternative solutions in some areas,” says Langas. “There is no such thing as a copy-and-paste basin, but there are principles that work everywhere.”

The intensive dialogue with the responsible authorities, which was necessary throughout the planning phase, also included drawing up a detailed sampling protocol. Rainfall volumes were measured, water samples were taken, and extensive chemical and microbiological analyses were carried out. A certified laboratory handled this work in line with international standards. The results were very promising: low nutrient levels, no pathogens that pose a health risk, and no legionella. “We continuously monitored the water quality before and after construction. It already meets many of the requirements set out in EU Water Reuse Regulation 2020/741 and in the Lithuanian hygiene standard HN 92:2018,” says Langas.

Among other things, the international SuDS handbook for sustainable drainage systems served as a reference, with its recommendations on sedimentation basins, permanent water zones, landscape design and maintenance.

“What matters now is time,” says Langas. “An ecosystem has to establish itself; then the retention rate increases, and future uses can be calculated with confidence.”

UV disinfection could broaden the range of uses

Once the pond ecosystem has stabilised and standardised data series are available, the town will adopt more detailed rules for use, define water extraction points and clarify logistics. In parallel, the region is working to expand legal leeway so that municipal water recycling applications can take their place as a standard tool of climate adaptation.

The first intended use is deliberately pragmatic: cleaning the sewer system. In addition, the treated water is to be used by the so-called “eldership” – the responsible administrative unit – to irrigate public green spaces. In the longer term, further applications are conceivable, ranging from watering newly planted trees to use as firefighting water. “We have already run our first successful tests, using the water, supplied by our municipal utility, to clean the pipe network,” says Šatkus. The next step is to gradually build up trust in this new practice. The technical implementation, he notes, is often easier than gaining public acceptance. In the medium to long term, additional uses can follow, while extra UV disinfection could further expand the range of applications, for example for washing municipal vehicle fleets.

A conscious choice: no fence, but transparency

With an increasing number of uses, a dedicated operations and quality management plan will be needed: Who extracts how much water, and when? What minimum quality applies to which use? Who documents and who maintains the system?

The pilot is pioneering, however, not only in terms of legislation, authorities, municipal actors and procedures. It is also breaking new ground in how the topic of water recycling is communicated to the general public. It is no coincidence that the retention basin was built without a fence in a central and much-visited area of the town, rather than as an enclosed technical facility somewhere out of sight. Those responsible deliberately decided against a fence and in favour of openness and transparency. Targeted communication activities are also planned: information events, training formats, presentations in schools and community centres, and on-site conversations at the pond itself, turning the site into a place of learning about hydrology, ecology and climate adaptation. The municipality also intends to be active on social media.

No compromise on quality, but smarter management of resources

The aim is to raise awareness of the potential of rainwater as a resource literally lying at our feet. “People need to understand that this is not about compromising on quality, but about managing resources more intelligently,” emphasises Šatkus .

In this, Gargždai can draw on the experience of other WaterMan partner regions, such as Kalmar in Sweden. There, it has also become clear that many things are technically feasible – but they also need to be well communicated and socially accepted.

In national debates in Lithuania, critical questions can be expected at first. Why all this effort in a country that has ample groundwater and surface water? The answer lies in the long-term climate data, which tell a clear story: extreme weather events can be expected to increase in Lithuania as well. Here, too, it will no longer be possible to insist on drinking water quality for every use in the future. Instead, a fit-for-purpose approach is needed: the appropriate water quality for each specific use. For the vast majority of applications, drinking water quality is not necessary. People have simply become accustomed to it, because it has long been available in abundance. Retention ponds that also allow direct use of the stored water offer a first, low-threshold path into water recycling – with low maintenance costs.

“We must not lull ourselves into a false sense of security,” says Langas. “Precisely because we still have water in abundance today, we should already be learning to use it responsibly.” What counts here is safety, transparency and practicality. And it takes visionaries who are also pragmatic implementers – people like Valdas Langas, Mindaugas Šatkus and Feliksas Žemgulys.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

In the past, the car park in front of the indoor swimming pool in Braniewo, Poland, was heavily sealed – an urban heat island in summer and, in spring, an exacerbating factor for flooding. Today, a rain garden stores water, cools the surroundings, and enhances the area. So simple, so important, so transferable across the entire Baltic Sea Region.

Completed in late summer 2025, the rain garden in the middle of the indoor pool’s car park immediately catches the eye. With its naturally shaped topography of gently contoured basins, long, stone-lined depressions planted with perennials, it is not only beautiful to look at, it is functional. When the first heavy rain arrived again in mid-September, Jerzy Butkiewicz pulled out his smartphone and hurried over. He had overseen the WaterMan project for the Braniewo municipal administration from day one and reached the site in time to capture the moment. And there it was, exactly as intended: lots of water streamed from the surrounding asphalt through the designated openings in the kerb and collected in the basins, where the soil matrix stores it and gradually releases it to the groundwater.

Consistently putting the obvious and proven into practice – that, too, is progress

Sometimes progress is not found in the newest technology but in the courage to tackle the obvious and proven – and to implement it well. In Braniewo, a small town in northern Poland, the rain garden in the car park of the municipal indoor swimming pool “Zatoka” is no spectacular high‑tech project, but a visible measure with real impact. The starting point was fairly unremarkable, essentially everyday urban management. The “Zatoka” is surrounded by concrete surfaces and asphalted car parks. A setting which has become increasingly problematic with climate change. In summer, temperatures here could exceed 40 degrees Celsius. And when it rained, the water ran straight off the asphalt into the sewer system and on to the flood‑prone Pasłęka River. At the same time, the few existing green islands visibly withered during dry spells unless they were watered regularly with valuable drinking water.

It is a situation familiar in many places today. Yet the right measures are not taken everywhere with the same resolve. Braniewo’s rapid shift from municipal debate to decisive action owed much to a new optimism about water recycling, born of a fortunate alignment of factors. The Institute of Civil and Environmental Engineering at Gdańsk University of Technology, under the leadership of Professor Magdalena Gajewska and contributing to the WaterMan project, identified the indoor pool as an ideal site for two pilot measures at once: the world’s first facility for recycling swimming-pool backwash water and, next door in the car park, a much-needed rain garden as a nature-based solution. High-tech at one end, low-tech at the other: two points on a scale where future effectiveness in water recycling can grow. Added to this was Jerzy Butkiewicz, who oversaw both measures on site for the Braniewo municipal administration, supported implementation, and was there with his smartphone at the decisive moments. As the city administration’s water lead, he was the local champion who, quite literally, set things in motion.

The key is to use the existing topography wisely

Together with Jerzy, Gajewska and her research team developed a rain garden for the Zatoka indoor pool’s car park. The basic idea is longstanding: rain gardens are landscape systems that retain stormwater on site and let it infiltrate gradually into the soil. That eases pressure on the sewer system, waters the planting, and cools the microclimate. Yet despite being well established, rain gardens are not plug-and-play. “Every site brings different requirements, from soil and slope to water flows,” explains Magdalena Gajewska. To achieve the desired storage and cooling effects, water routing must be carefully designed and tailored to local conditions. That means nature-based design, plant diversity, and hydrological elements such as retention swales and sediment barriers. “The trick is to make smart use of the existing topography. Ideally, you place a rain garden where there is already a slight gradient.” Exactly the case at the Zatoka car park.

Everything flows. That may be true once a rain garden is finished, but not always during planning and construction. In Braniewo, too, the process wasn’t entirely frictionless. “Some technical details were debated quite passionately between the university and the landscape contractors, for example, the height of the troughs or the use of large natural stones instead of concrete,” recalls Butkiewicz. As on-site coordinator, he managed the coordination between the university, the planners and the contractors, ensuring theory and practice moved in step – and that, after some hard-fought compromises, everyone could shake hands again. “It was a pilot tested under real-world conditions, with the aim of learning from it and passing the concept on.”

Now everything is in place: a flower meadow of around 400 square metres; a 210-square-metre retention bed and additional planting; lampposts with greenery; a planted retaining wall; and new green islands.

An ideal location for communication as well

The site was ideally suited not only because of its natural slope and its proximity to the Recycling of Pool Water pilot measure, but also as a platform for communication and education. Many residents of Braniewo and the surrounding area visit the indoor pool regularly, and school classes come here daily for swimming lessons. In future, visitors will pass the rain garden and the newly installed information boards on their way in. These explain infiltration, evaporation and water cycles. They also illustrate why the large natural water cycle now needs to be complemented by small water‑recycling loops if we are to adapt our water management to climate change. Further educational activities and events are planned, such as a family picnic around the rain garden. “What we are showing here, too, is that you can get started without huge investments or years of planning,” explains Gajewska. “The elements are simple, the technology is available, and the impact is immediately measurable.” This could be a blueprint for other municipalities looking for quick, visible solutions, Butkiewicz adds. Here in Braniewo, it is also about maintaining a liveable, green urban space through more frequent dry periods, without wasting valuable drinking water. “We want not only to retain water here but also to share knowledge and inspire enthusiasm for smart solutions.” Delivering the two measures, rain garden and swimming‑pool water recycling, simultaneously and right next to each other increases local visibility and demonstrates a holistic approach to urban water resilience.

A practical invitation to other cities to do the same

Igor Kaniecki, a member of WaterMan’s international project management team who supports a wide range of pilot measures, also underscores the value of seemingly simple solutions: “In the Baltic Sea Region, no one will die of thirst in the next 50 years. That’s out of the question. What will become more difficult to maintain are the pleasant, familiar things: public gardens, greened city centres.” These nice-to-have elements risk becoming a municipal burden under climate change – unless we consciously decide, in good time, to change course and stop using valuable drinking water for every application. “Every drop counts,” says Kaniecki. Often you don’t need large volumes to secure the local water supply in the short and medium term. And in humid areas like the Baltic Sea Region, this also includes solutions you might not immediately associate with the term “water recycling”.

So it doesn’t have to start with multi-million-euro facilities. It can begin in a car park, with a few square metres of ground, a budget of just over €60,000, thoughtful planning, and a willingness to collaborate. The approach is scalable and directly applicable. A practical invitation for other cities simply to go ahead and get started.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

It is astonishing, really, that recycling swimming‑pool water has never been systematically tested before. In this sense, the pilot in Braniewo – set up by the local municipal administration in cooperation with the Gdańsk University of Technology – is a true pioneering achievement, with encouraging results.

Perhaps it takes first‑hand experience with prolonged drought and water scarcity for our attention to turn to all the obvious sources for water recycling. When the grass on the car park in front of the public swimming-pool is already turning brown and the neighbouring sports field has to be watered constantly just to remain playable, while inside people are splashing around in thousands of hectolitres of valuable drinking water, one thing becomes clear: in times of climate change, swimming in a man‑made pool could become as much of a “nice‑to‑have” as playing football on green turf. Unless, that is, we embed it sensibly in a circular water‑management approach in which, after appropriate treatment, it can become a valuable resource – whether for irrigating green spaces, cleaning the municipal sewer network, or watering the adjacent sports field. In any case, for the future. Because the people of Braniewo, in Poland’s north, will continue to enjoy going for a swim.

The Discovery of a Resource

Swimming pools use large amounts of drinking water every day, which is regularly replaced or discharged during backwashing of the filters. Just as regularly, tanker trucks could pull up here to draw off this water – once treated – from a newly created reservoir and recycle it for various uses. What began as a thought experiment has, within a few years, become an ambitious real‑world laboratory for water recycling. It took an almost Herculean technical, political and legal effort to create the necessary preconditions. In doing so, Braniewo is breaking new ground at the European level as well. Even in the context of the EU Water Reuse Regulation, the reuse of swimming‑pool water is still uncharted territory.

Because the basic idea sounded so compellingly simple, it was all the more surprising that, in fact, no information on similar test projects could be found anywhere. Apparently, no one had ever tried it. Yet, so the assumption went, public acceptance of recycled swimming‑pool water as a resource for irrigating sports grounds and green spaces should be comparatively high. “People often struggle to accept treated wastewater. But water they use themselves when swimming seems less alien to them,” says Krzysztof Czerwionka, who oversees the project technically and conceptually on behalf of the Gdańsk University of Technology. In this respect, such a project could be an important door‑opener for a more comprehensive water‑recycling strategy that taps into additional sources. In effect, a first step in familiarising the general public with the idea.

Part of a Comprehensive Concept that Also Includes Knowledge Sharing

The project team, however, soon realised just how challenging the task would be. What seemed simple at first proved riddled with pitfalls and stumbling blocks: chlorine in the water, limited space for tanks, uncertain volumes, and a thicket of regulations. Every step raised new questions and challenges. Sub-projects, such as blending the end product with rainwater, were tested and then dropped. What had looked like a straight path turned into a winding process of trial and error.

Once a feasible setup had been defined, the team first tested the treatment process under laboratory conditions at Gdańsk University of Technology. The principle was straightforward: backwash water from the filtration system is collected, temporarily stored, filtered and disinfected using UV light. A dual monitoring system, manual and automated, ensured water-quality control. Shortly after the initial lab trials, work began to install the pre-tested recycling system on a larger scale next to the filtration plant in the basement of the indoor pool. “To get the equipment into the room, we even had to enlarge the building’s gate,” recalls Jerzy Butkiewicz, the municipal official responsible for water in the Braniewo city administration. On site, he had to coordinate planning, administration, technicians, and construction firms – also a challenging task. The partner institutions followed different procedures, language barriers complicated coordination, and everything had to run alongside day-to-day operations: pushing tenders through, finding contractors, convincing the authorities. Butkiewicz became the pilot’s quiet hero, keeping things moving despite all setbacks.

In the end, the team delivered a small but fully functional system: dechlorination tanks, UV filtration, and a loop that converts utility water into a usable resource. The treated water is collected and stored in a new reservoir under the car park.

A visit to Braniewo. Even outside the indoor pool, it becomes clear that this pilot measure is part of a broader concept for modern water management in which education and knowledge sharing play an important role. The partners, the Gdańsk University of Technology and the municipality of Braniewo, have also created a rain garden on what was once a fully sealed car park, likewise within the WaterMan framework. It uses the site’s natural slope to channel rainwater from the asphalt into planted swales and hold it there longer. This allows the greenery to thrive, cools the surrounding area on hot summer days, and eases pressure on the flood-prone Pasłęka River during heavy rain. Information boards explain these links and also introduce the pioneering pool-water recycling pilot to pool visitors and school classes. Technically, the two initiatives are separate, they operate as distinct water cycles. And yet, attention is channeled here: from the visible rain garden to a facility hidden in the pool’s plant room and beneath the car park’s asphalt.

The Real Potential Could Be Unlocked in New Pool Developments

Czerwionka is visibly proud of what has been achieved. With the system now commissioned, Braniewo can recover up to 50 percent of the water generated during backwashing. Across the entire pool operation, that translates into savings of about 15 percent of the drinking water that previously went unused down the drain.

However, the environmental engineer is now also aware of the pilot’s limitations. “What we can already say is this: when retrofitting such a system into an existing pool infrastructure, you have to make many compromises.” In the conversion of an existing building, potentials remain untapped that could be realised if water recycling was taken into account right from the planning and construction of such a facility. In that case, the system could be scaled up and recycle substantially larger volumes of water every day.

In addition to backwash water, the large volumes of shower water generated in a swimming pool every day could also be treated using the same recycling process. In the existing piping system, however, shower wastewater is mixed with wastewater from the toilets. “So the lines would have to be separated; rebuilding that in an existing facility is too complex,” explains Czerwionka. Even so, being able to highlight these opportunities to municipalities planning a new pool is a valuable outcome in itself. The pilot may not be a grand slam yet, but it already offers a concrete example of how innovation can take shape under difficult conditions. And in the Baltic Sea Region, grand slams are not necessarily required: often a few small measures, taken together, are enough to ensure local supply security. There are, after all, plenty of public pools in the region.

But why focus only on filter backwash, why not recycle the actual pool water as well? That’s where things get more complex, Czerwionka explains. Pool water isn’t ordinary wastewater: higher levels of chlorine, direct contact with bathers, and strict hygiene requirements make such an undertaking far more demanding. Backwash water, by contrast, is produced regularly, is easy to define as a process stream, and can be treated efficiently in a closed loop.

Not Only Technology – Trust Also Has to Be Built, Patiently

What’s also not always easy is convincing people and organisations to use recycled water. Right next to the pool is the football pitch of the local sports club. It would be the obvious choice to water this turf in summer with treated swimming‑pool water in future. But the supplier of the newly laid turf has raised objections, says Czerwionka. The company offers a three‑year guarantee for the quality of its grass only when drinking‑water quality is used for irrigation. A test run will therefore only be possible later. Not only technology, but trust, too, has to be built – drop by drop.

Jerzy Butkiewicz, who now wants to put the recycled water into circulation within the municipality, also had to adjust his expectations a little at first. The initial application, flushing water for municipal sewer cleaning, was deliberately chosen to be manageable. If operations remain stable and there are more precise insights about the water quality that can be maintained over time, further uses will be considered: alongside other municipal tasks such as watering green spaces, also private uses, for example by allotment gardeners. “We are planning a simple draw-off system for small users,” Butkiewicz explains. “This will give citizens direct access and bring the topic into everyday life.”

A Big Long‑Term Perspective

Even if the tap can’t be turned fully on right away, the solution, Czerwionka argues, has strong long-term potential, especially compared with other water sources. “Rainwater is often only seasonally available. Pool water, by contrast, is generated continuously and its quality can be closely monitored.” And the system’s educational value should go beyond information boards in the car park: school classes visiting the pool will gain hands-on insights into sustainable water strategies and be able to tour the installation.

This makes the issue tangible and strengthens understanding of the basics: in times of climate change, the Baltic Sea Region will also face phases of drought and drinking-water shortages. That is why we need to build small recycling loops into the large natural water cycle – loops that make water available again more quickly for various uses, in different, fit-for-purpose quality levels.

From Unknown Terrain to Fertile Ground

A small loop like this now runs in the basement of Braniewo’s indoor pool. Getting there meant venturing into unknown territory and learning by trial and error. The result is impressive. “Pilot measures like this require patience, pragmatism and commitment,” says Butkiewicz. “But they show that sustainable change can start small and grow from there.” Demo visits will help stakeholders across the region to experience this first-hand. What was once unfamiliar ground is now fertile soil for new ideas and projects – freshly watered with recycled filter backwash.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

A pilot project on Bornholm demonstrates how forward-looking water recycling for agricultural use can succeed with well-established technologies. Even more importantly, it has sparked significant momentum in Denmark’s national policy debate.

High-tech solutions are not always necessary to build future-ready projects and structures for water recycling. This core idea of the WaterMan project was demonstrated in an exemplary way on the Danish Baltic Sea island of Bornholm. Here, a team led by Paulo Martins Silva, project manager at the local utility Bornholms Energi & Forsyning (BEOF), revived a technique many had forgotten: the slow sand filter (SSF). The principle is straightforward. Wastewater that has already undergone treatment at a wastewater plant percolates slowly through layers of gravel and sand. The cleaning effect is strong enough that the output of the filter can be safely used to irrigate edible crops in agriculture. One visible sign of how effectively the filter works is the so‑called Schmutzdecke – the biofilm that forms at the top of the sand layer. And, incidentally, at WaterMan partner meetings this term repeatedly caused amusement – especially when Danish colleagues pronounced the German word with a Danish accent. The technology originated in Germany, and the old instruction manuals from the 1970s are where the term first became established.

“The idea to revive a slow sand filter came directly from practice,” Silva explains. “A senior colleague contributed know-how from earlier projects on artificial groundwater recharge. Building on that, we worked with the engineering consultancy Envidan to develop the design.”

Deliberately low-threshold – and therefore easy to replicate

The BEOF team installed the sand filter right next to the Svaneke wastewater treatment plant, starting with a small‑scale pilot. The installation is essentially a plastic cylinder about two metres high and two metres wide, filled with a 20‑centimetre layer of crushed granite and 80 centimetres of sand. A hose pump feeds the already‑treated wastewater into the filter. Once filtered, the water flows into an intermediate tank where it can be drawn off for agricultural irrigation. Sampling points and online sensor connections were also included to support monitoring and operation.

From the outset, the aim of the Bornholm pilot was to produce fit‑for‑purpose water for agricultural irrigation, directly adjacent to the wastewater plant and aiming for EU quality class D. The team therefore considered key factors for creating a local water loop: short transport distances, low energy use and simple distribution options, for example via tanker trucks or inexpensive PE pipes to neighbouring fields. This low-threshold approach was intentional, making the solution easy to replicate and adapt elsewhere. Low‑tech, low‑cost, robust and energy‑efficient – these characteristics were meant to make the SSF approach attractive across the Baltic Sea region, especially for places wanting to move quickly from discussion to hands‑on implementation.

With relatively little effort, slow sand filters can create new small recycling loops within the larger water cycle and make water available for agriculture in dry periods. Not drinking-water quality, but water clean enough for irrigating edible plants or growing seeds. On Bornholm, a local farmer was immediately willing to test the sand-filtered water on open fields. “We wanted the setup to be so simple that farmers can easily understand how it works,” says Silva. “A reliable tap point with predictable quality, and clear arrangements for distribution and storage.” What actually happens on the fields, however, is ultimately defined by regulation.

Recycled water shows strong vertical plant growth

And it was precisely at this point that big politics suddenly got in the way of the small, ambitious pilot. Denmark’s Ministry of Agriculture had opted out of the EU Water Reuse Regulation, arguing that water recycling for agriculture was not relevant and offered no viable business case nationally. This removed the regulatory basis for the planned field tests with nearby farmers.

But the BEOF team refused to be discouraged and quickly shifted course. Instead of irrigating open fields, the pilot was reconfigured as a controlled small-scale test bed. Directly next to the sand filter, a test greenhouse was built in cooperation with another EU project. Water from the sand filter was pumped from the intermediate tank into a second tank next to the greenhouse and delivered to the plants via drip irrigation. This setup offered a safe, controlled environment to validate water quality, observe plant reactions, and fine-tune system operation. Even on this smaller scale, the team would be able to demonstrate the treated water’s readiness for use and build acceptance. “You can’t wait until the regulatory framework is perfect,” Silva says. “In the greenhouse, we can test the recycled water safely, collect data, and show the benefits.”

Unexpected gamechanger: new EU directive forces a rethink

Spinach plants at the local Frennegaard farm were among the first to be irrigated with the recycled water. They grew well – an important proof point. At the same time, the team undertook extensive outreach: to local farmers, municipal officials and other regional stakeholders. A workshop organised with the farmers’ association combined a demonstration visit at the Svaneke plant with discussions about practical and regulatory issues. While national policymakers had opted out of water reuse, local farmers on Bornholm showed clear interest. They saw a business case: recycled water could be valuable during increasingly frequent drought periods.

These first farmers, already affected by drought, were not deterred by the political headwinds and engaged in lively discussions about legal hurdles, fair cost-sharing and very practical questions – above all, how the water would actually reach the fields where it was needed. This combination of on-site demonstration and open dialogue proved to be an important door-opener. “Often the psychological barrier is bigger than the technical one,” Silva notes. “Once people see the system and observe the first results, acceptance grows.”

None of this was in vain. Soon it became clear how quickly the political winds can shift—and how a pilot project can regain political momentum. In November 2024, the new EU Urban Wastewater Treatment Directive (EU 2020/3019) was published, requiring water reuse to be considered whenever large wastewater treatment plants are upgraded – and this time, EU member states cannot opt out. Denmark must now align with the new rules, and BEOF on Bornholm already has a functioning demonstrator, complete with data, technology, and committed partners.

“Suddenly, everyone is talking about water reuse in Denmark again.”

Suddenly, the team found themselves in the right place at the right time. When the political context shifts, even a small project can have major impact: the Bornholm sand filter helps anchor the renewed national debate on water reuse with a tangible example. BEOF’s success cannot yet be measured in cubic metres of recycled water. But the island has shown that water recycling is not a future vision but an actionable option using available means. Or, as Paulo Silva puts it: “We wanted to prove that it works – and we have contributed significantly to the national debate on water recycling.” In Denmark, the signs now clearly point toward scaled-up use of slow sand filter technology. In the broader Baltic Sea Region, they do so anyway. As a low-threshold technology, it is a “low-hanging fruit” that can be picked relatively easily elsewhere.

Not a self‑running solution – many questions remain

Nevertheless, slow sand filter projects do not run themselves. Many details remain open – an issue that repeatedly surfaced in the Q&A sessions at WaterMan partner meetings. Under which site and operating conditions is the SSF most effective? How can the large space requirements for slow sand filter systems intended to treat agriculturally relevant volumes of water best be managed? Which micro-pollutants are removed to what degree, and where might additional treatment stages such as activated carbon be necessary? What are feasible timelines for commissioning? What clogging frequency and maintenance intervals should be assumed in operational planning? And what are realistic operating and maintenance costs? Each of these questions depends on local context and requires careful consideration.

But the general direction is clear. “Water is a limited resource—even in the north,” says Silva, who comes from Portugal. “The faster we add local loops, the more resilient our water supply becomes. The slow sand filter is one building block among several—but an extremely accessible one.”

This is precisely the idea behind WaterMan: integrating small, pragmatic loops into the larger water cycle, sharing data, building acceptance, and enabling scaling. Change starts locally. Another core principle strongly confirmed by the Bornholm slow sand filter pilot.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

After several droughts, it became clear that the municipality of Kalmar in Sweden urgently needed a new water strategy. The other important conclusion was that in order to develop it quickly, everyone should just get down to work and test out alternatives. Here is a report from a place where there is a lot going on and everything is flowing in the right direction.

“I use recycled water for irrigation” – the words are written in big letters on a tanker trailer pulled by a tractor as it bumps along through the city of Kalmar on the south-east coast of Sweden in June 2024. The trailer is on its way to a green area with newly planted trees that require special care in their first few years, especially when it gets warm and dry. Until recently, this was done according to the old practice – using ordinary drinking water from the tap, which seemed to be available in an unlimited supply. But in the hot summer months of recent years, water regularly became scarce, while the groundwater level dropped dramatically. Several water crises have hit Kalmar hard. But instead of lively discussions about new strategies and master plans, the Swedes reacted with their usual pragmatism. In various areas of local water management, both private and public, they got straight down to work and tested out alternatives. Alternatives where water is drawn from other sources in order to make it available for different uses. Is it really absolutely necessary to water urban green spaces with precious drinking water?

“The psychological hurdles are a bigger problem”

Absolutely not. It is also possible, for example, to use water from the local wastewater treatment plant disinfected with UV radiation, which significantly reduces the contamination from germs and bacteria. The Parks and Green Spaces Department is also making its contribution with this pilot project and Klas Eriksson is responsible for the implementation. He and his team purchased the components for the new system, installed them and got them up and running. “It had its technical pitfalls, but everything was doable. The necessary components were all readily available, we just had to put them together in a way that made sense,” he says. A small pumping and recycling station is now located on a canal through which the treated wastewater from the Kalmar wastewater treatment plant is channeled into the sea and back into the large natural water cycle. This station takes some of the treated water, exposes it to UV disinfection and then fills the tanker – and off it goes into the parks and green spaces. They are watered directly from the tank using a hose system. The system has been in use since June 2024 and put simply: it works. Plus, the nutritions still in the water are perfect for fertilising the soil.

Water that could also be used to water lettuce and strawberries

“The psychological hurdles are a bigger problem,” says Eriksson. “People still have to get used to the idea of using treated wastewater and other quality levels of water in their everyday lives.” Hence the prominent slogan on the tanker trailer. The aim in Kalmar is also to familiarise the public with the fact that they will no longer be able to use precious drinking water obtained from groundwater everywhere and all the time. However, Eriksson first had to do a lot of convincing at his office, among his colleagues from the gardening department, who will be working with the system every day. “There were some critical voices as to whether the handling of treated wastewater was hazardous to health,” he reports. Some resistance was to be expected, however, which is why Eriksson had taken precautions: he had work place safety experts in to draw up scientifically founded reports. He informed his colleagues in detail about the results during training sessions – “harmless” – and took the opportunity to invite representatives of the company that cleans the sewers in Kalmar. “They are working with wastewater treatment plant water that is not even disinfected. And there haven’t been any problems there either.” He could also reassure his employees that thanks to the UV disinfection the water achieves even quality level A, suitable for irrigating food crops such as lettuce and strawberries in accordance with the EU Water Reuse Regulation 2020/741.

“The various players need to communicate even better and take note of each other’s activities”

The employees’ skepticism has noticeably decreased, particularly after the first practical experiences with the system. The principle seems to be proving its worth in Kalmar simply by just getting started and carrying out testing in different areas – on a smaller as well as a larger scale. The municipal water company Kalmar Vatten AB is currently building a brand-new water recycling plant in the city that opens in 2027, which may even be producing drinking water from wastewater on a large scale. The utilisation and harvesting of rainwater are one of the key points to consider in all land development projects. The sports department recently tested whether it could use rainwater from retention ponds to water football pitches. And much more besides. The joy of experimentation and the spirit of optimism in various areas does not mean, however, that these new water activities are completely uncoordinated. Hanna Berggren is responsible for ensuring that these projects and activities work together as well as possible. “I was hired to manage Kalmar Municipality’s new comprehensive water strategy, and I had a lot to learn myself,” she explains. “One of the most important things I learnt was that the various stakeholders and departments needed to communicate much better and take note of each other’s efforts to recycle more water in the first place.”

Creating a coherent overall picture and then putting it into practice

In the meantime, a lot has been achieved in this field too. For example, the experts of Kalmar Vatten AB provided Eriksson and his team with advice and support when it came to commissioning the UV disinfection system. The company is also very interested in the experience gained from the mobile system. They are considering using something similar at a later date to disinfect water in the new large-scale plant. Nevertheless, much remains to be done for Berggren. In the medium to long term, she must draw up a coherent overall picture of what quantities of water will be needed in the future, in what kind of quality and for which applications – and she must work towards making this a reality.

“What makes economic sense depends on the individual local setting”

Sometimes there are still small problems: “The department of Parks where Klas Eriksson works should contact the sports office again and offer to work with the mobile system.” Meanwhile, it has become apparent that the rainwater retention ponds from which the football pitch is to be watered sometimes almost dry out in the hot summer months. According to Berggren, larger infrastructure measures may also be involved: “There are also plans here in Kalmar to use treated grey water – i.e. slightly contaminated wastewater that is free of faeces – for flushing toilets in the future.” In order to realise this across the board, completely new pipelines would be needed. This is still a long way off, but a dual-pipe system has already been installed in a pilot building at the Kalmar hospital. A feasibility study is currently investigating how this can best be utilised and perhaps even connected to the new water recycling plant.

In principle, a completely new attitude to water is required in this region

Added to this are the valuable suggestions that both Berggren and Eriksson receive as representatives of the municipality of Kalmar in the “WaterMan” project’s peer-learning programme. In this Interreg project, representatives from various countries bordering the Baltic Sea are exchanging ideas on new water strategies that suit the region’s specific circumstances in light of the noticeable effects of climate change. In Braniewo in Poland, for example, they are considering recycling water from swimming pools. In Klaipeda, they are building new retention ponds because there is now much more water to collect due to increased heavy rainfall events – also as a result of climate change – which can then be put to good use during periods of drought. Something similar is currently happening in Västervik, Sweden, where they are watering sports fields and cemeteries, for example, with the help of new “multidams”. “Our UV technology could also be used for collected rainwater,” explains Eriksson. “But if you have to build such basins from scratch, it could also be cheaper to disinfect sewage treatment plant water.” It always depends on the individual local setting as to what makes economic sense.

As well as the big picture, there are still many details to be worked out. According to Berggren, this is currently taking shape as part of WaterMan. “We will also have to understand water as a valuable resource around the Baltic Sea in the future.” This includes accepting different qualities of water for different uses and tapping into other sources of “usable water” besides groundwater. In principle, a completely new attitude to water is required in this region, where there has always been an abundance of water. Nobody will have to suffer from thirst, but perhaps they will have to say goodbye to a few cherished habits, such as watering their own private garden with drinking water. There are alternatives and they are already working in practice. That’s the good news that is coming out of Kalmar right now.

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About the “WaterMan” project

More information: interreg-baltic.eu/project/waterman/

Date: 30 June 2024

At the first of two WaterMan Roundtables in Brussels, the discussion flowed openly and directly: Do we need specific water-recycling regulations for Europe’s humid regions? And to which extent can the existing EU Water Reuse Regulation (2020/741) be stretched to support other use cases, beyond its agricultural focus? It was the beginning of a dialogue with ambitions reaching well beyond policy detail.

It’s mid-January – a time of year when drought and water scarcity still feel like distant problems for many people in Central and Northern Europe. But not on this Thursday morning at the Renaissance Hotel in Brussels. Once again, several now well-known infographics are being projected onto the wall or shared via videoconferencing for online participants. There are water-blue pie charts and bar graphs that have visibly shrunk over time, red zones surrounding the Baltic Sea that have grown larger and darker in recent years. For most of the more than 100 participants, policy-makers and experts gathered in the room and online, the core issue is already abundantly clear: due to the seasonal increase in droughts and water shortages, water recycling is no longer just a concern for dry, hot southern Europe. It is becoming an increasingly pressing issue for the humid zones of Central Europe and the Baltic Sea region as well. This is precisely what the “WaterMan” project, one of the organisers of this event, is all about: supporting pilot measures in Baltic Sea countries that push ahead with pragmatic solutions and explore what is already technically feasible today. Gathered around the symbolic roundtable today are not only representatives from the Baltic Sea Region, but also, for instance, from local Flanders in Belgium and other EU countries. More and more humid regions in the EU are being affected. And here and now, they are engaging in exchange.

The key question: Is the current regulation enough?

As we are in Brussels, at the heart of it all are political questions: Across the EU, it has long been clear that we need to recycle wastewater and find more sources of water beyond just groundwater.

In the semi-arid zones of Southern Europe, this has been both a necessity and standard practice for some time. That’s why the EU introduced the Water Reuse Regulation 2020/741, which has been in practical application since June 2023. In terms of water recycling, it offers helpful methodologies and practical guidance, for example on water quality standards and risk assessment protocols.

However, the regulation focuses on one specific use case in particular: the irrigation of agricultural land with recycled water from municipal wastewater treatment plants to mitigate year-round water scarcity. What one needs to be mindful of, though, is that these are requirements and framework conditions that primarily apply to southern European countries such as Spain and Greece. Things look different in the humid regions of Central and Northern Europe. Here, the situation is more about seasonal fluctuations between too much and too little water – and about a significantly broader range of uses for recycled water: in urban parks, sports grounds, industry, or even private households. Consequently, identifying additional sources of water beyond treated municipal wastewater is a much higher priority here. And in places where climate change is causing more frequent extreme rainfall events, intensified rainwater harvesting is the most obvious solution. The question is simply: how can this be achieved?

This is where the conversation began – and where some of the core questions of the roundtable emerged:

Can Regulation 2020/741 be meaningfully applied beyond agriculture?
Should the regulation be expanded as part of its upcoming review by 2028?
Do we need a dedicated regulation for water recycling in humid regions, or would general EU guidelines be more suitable, leaving detailed regulation to member states in line with the subsidiarity principle?

Insights from practice and policy

Valentina Bastino from the European Commission made it clear: The initial focus on agriculture was logical, considering the EU’s single market and food hygiene requirements for agricultural products. But she also stressed that the Commission is eager to gather more data from other use cases, including anecdotal evidence. The goal is to better politically support water recycling in humid regions, whether through an expanded regulation or new guidance frameworks.

Practical insights came from two frontrunners: policy coordinator Kor Van Hoof from the Flanders Region in Belgium and Klas Eriksson from Kalmar in Sweden. Both shared how local projects have made progress without waiting for tailored EU regulations.

In Kalmar, municipal wastewater is already being recycled to irrigate public green spaces. Eriksson explained how applying the water quality standards defined in the existing regulation helped ease concerns, even though they technically fall outside its official scope. After all, water considered safe for irrigating food crops is more than safe enough for city parks. The water quality standards proved extremely useful, even though their application in Sweden technically falls outside the scope of the EU Water Reuse Regulation.

Flanders, meanwhile, has implemented national or regional regulations that, for instance, require rainwater harvesting in new buildings. This measure offers valuable inspiration for other regions and even EU-wide efforts.

Regulation vs. reality: striking the right balance

The concluding panel discussion highlighted a common sentiment: expanding the EU regulation could be helpful – but only when applied with care. Participants stressed the need for more data, more experience, more pilot projects, and more locally grounded knowledge. By this point in the discussion, it had also become clear that the many local dimensions of water recycling inevitably bring the issue into the realm of subsidiarity: what can be handled more effectively at local, regional or national level should be addressed there – not higher up. As Valentina Bastino from the European Commission summed it up, perhaps a new EU regulation isn’t what’s needed after all. Maybe it’s about providing smarter EU-wide guidance that supports and simplifies local initiatives.

A starting point, not a conclusion

That’s precisely the spirit in which the roundtable ended: with a call to keep the conversation going. WaterMan project coordinator Jens Masuch and Tobias Facchini from the Lead Partner Region Kalmar County summarised the event’s key takeaway: We don’t need all the answers today. But we do need the dialogue.

And this was only the beginning. The conversation will continue on 6 November 2025, at the next WaterMan roundtable in Brussels. By then, a policy paper will be drafted, reflecting the latest experiences with water recycling in humid regions, and offering recommendations for adapting legal frameworks, whether at national or EU level.

» Watch the Roundtable Discussion in full length

Umbrella 2.0 Report: “Entry points” to EUSBSR Cooperation

Municipal Foresight: Wastewater Becomes a Resource

Political Room for Manoeuvre and Technical Clarity

Legal Certainty Through New Structures

A Model for the Entire Baltic Sea Region

Knowledge Creates Room for Action

— About the “WaterMan” project

Climate change has accelerated the shift in thinking

Moving quickly from talk to action – and learning fast

The real innovation: decentralising the retention ponds

The task ahead: developing a business case

Multifunctional tools for water resilience in the Baltic Sea Region

Start with sports fields and lead by example

— About the “WaterMan” project

A flow of future-oriented ideas

Making water recycling tangible in an emotionally charged place

A small setback becomes a catalyst

Sometimes willingness to learn is more valuable than prior knowledge

What to do with winter water?

The first dry summer will surely come

— About the “WaterMan” project

In Lithuania, this made Langas and his team pioneers

Pioneering work – above all in the legal framework

A textbook example of nature-based rainwater treatment

UV disinfection could broaden the range of uses

A conscious choice: no fence, but transparency

No compromise on quality, but smarter management of resources

— About the “WaterMan” project

Consistently putting the obvious and proven into practice – that, too, is progress

The key is to use the existing topography wisely

An ideal location for communication as well

A practical invitation to other cities to do the same

— About the “WaterMan” project

The Discovery of a Resource

Part of a Comprehensive Concept that Also Includes Knowledge Sharing

The Real Potential Could Be Unlocked in New Pool Developments

Not Only Technology – Trust Also Has to Be Built, Patiently

A Big Long‑Term Perspective

From Unknown Terrain to Fertile Ground

— About the “WaterMan” project

Deliberately low-threshold – and therefore easy to replicate

Recycled water shows strong vertical plant growth

Unexpected gamechanger: new EU directive forces a rethink

“Suddenly, everyone is talking about water reuse in Denmark again.”

Not a self‑running solution – many questions remain

— About the “WaterMan” project

Water that could also be used to water lettuce and strawberries

Creating a coherent overall picture and then putting it into practice

In principle, a completely new attitude to water is required in this region

— About the “WaterMan” project

The key question: Is the current regulation enough?

Insights from practice and policy

Regulation vs. reality: striking the right balance

A starting point, not a conclusion

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project

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About the “WaterMan” project