Chlorine-free swimming pool brings nature and recreation together in Diest
At the provincial domain De Halve Maan in Diest, Sweco, together with several partners, is developing the preliminary design for an innovative project where recreation and ecology converge. The Province of Flemish Brabant selected a natural outdoor swimming pool without chlorine, carefully integrated into the existing heritage landscape. The result is a sustainable and future-oriented swimming environment that responds to the growing demand for nature experiences and healthy leisure activities.
- Client
- Province of Flemish Brabant
- Location
- Diest, Belgium
- Sweco scope
- Design, construction team coordination, site supervision, landscape integration
- Partners
- Coussée Goris Huyghe Architecten, Polyplan Kreikenbaum Gruppe GmbH, GD&A Advocaten
From a traditional swimming pool to a natural swimming experience
The project is driven by the ambition to transform a traditional chlorine-based swimming pool into a natural system. Sweco developed a design in which water purification is achieved through a biological filtration system using plants and minerals, while the technical engineering was designed by Polyplan. This approach creates a natural swimming experience while simultaneously enhancing biodiversity across the site. As a result, the swimming pool becomes not only a recreational destination, but also an ecologically valuable element within the landscape.
By combining natural filtration with thoughtful design, we create a sustainable swimming experience that integrates seamlessly with its surroundings.
Thomas Leuridan, Sweco project manager
Construction team approach ensures efficient delivery
For this project, a construction team approach was selected. The contractor is involved at an early stage of the design process, ensuring stronger alignment between design and execution. This collaboration will result in more efficient decision-making, improved feasibility and reduced risks during implementation. Sweco coordinates the entire process, from preliminary design through to site supervision.
Reuse and circularity as guiding principles
A key principle within the project is the maximum reuse of existing structures. The original swimming pool shape and technical infrastructure are integrated into the new design. All functions are accommodated within the existing buildings, with only a limited section of the former beach building being demolished. The filtration building loses its original function and is transformed into a spacious entrance area. All buildings are connected through a wooden canopy, further reinforcing the link with the heritage structure. This renovation is being developed with a strong focus on energy efficiency and circular materials.
A landscape where water and nature come together
The project extends beyond the swimming pool itself. The entire surrounding environment is being redesigned so that water, greenery and recreation blend seamlessly together. Particular attention is given to the nearby Webbekoms Broek nature reserve, as well as to the heritage assets present within the project area. New green zones, sunbathing lawns and shaded areas create a pleasant visitor experience while helping to reduce heat stress. The result is a destination where visitors come not only to swim, but also to relax in a natural setting.
Long-term sustainable impact
The chlorine-free swimming pool in Diest demonstrates how public infrastructure can evolve towards sustainable and future-oriented solutions. By combining ecology, technology and user experience, Sweco is delivering a project that responds to both current and future needs. It serves as an inspiring example for similar projects in Belgium and abroad.
