Water on Stage

future-oriented local water network for Hertogensite in Leuven

In times of urbanisation, longer droughts and more intense precipitation due to climate change, the importance of well thought-out water management with the circular use of alternative water sources, such as grey water and rainwater, increases significantly.

Thanks to large-scale reconstructions of urban neighbourhoods, action is possible in a relatively short period of time. Thus, the Hertogensite in Leuven, one of the largest new inner city developments (6ha) in Europe, is an extremely suitable location for a visible reference project.

Via the Water on Stage project, the research institute VITO, in cooperation with the drinking water company De Watergroep, project developer Resiterra and garden and landscape architect Atrium.Green, wants to draw up a design for a future-oriented, sustainable water network on the site.

The aim of this project is to investigate how we can reintegrate water into the urban fabric in a smart and clean way. We want to provide insights into the possibilities for water saving, local and circular water purification and the optimal use of rainwater within urban development projects.

The final design of the project resulted in a partially decentralised water network that addresses technological, economic, social and legislative aspects. It includes the use of alternative water sources for toilet flushing (preferential vacuum toilets) and for five new green-blue outdoor zones aimed at comfort, experience and the reduction of local heat stress.


Partners Resiterra nv, De Watergroep, Atrium Green





  1. We developed a local water network in a step-by-step and iterative way, each time evaluating it based on water balances, cost-benefit exercises and taking into account social and legislative aspects.
  2. The final design includes a water network that, on an annual basis, yields a total saving of 3.7 million litres of mains water (30%) thanks to the (re-)use of rainwater and greywater, the installation of vacuum toilets, etc.
  3. The designed water network includes five green-blue recreational outdoor zones to reduce heat stress and create a more pleasant outdoor experience.
  4. We drew up a monitoring and communication plan for the further development of the water network. It states which follow-up and steering is needed in the next phases and how we can communicate results to operators, residents and interested parties in a manageable way.


  1. The design of a future-oriented local water network requires close cooperation between the stakeholders. This is essential if we want to obtain a favourable cost-benefit structure and at the same time respect aesthetic, legal, social and ecological expectations and guidelines.
  2. Creativity is often lacking in the design of water networks. Therefore, it is important to involve not only engineers in the design, but also (landscape) architects. Thanks to their input, we were able, for example, to increase the feeling of comfort thanks to green-blue outdoor zones.
  3. Large new construction projects such as the Hertogensite in Leuven are the ideal location for innovation and optimisation of environmental issues. State-of-the-art concepts can be introduced here in a relatively short period of time.
  4. A site with the size and visibility of the Hertogensite in Leuven also has an important exemplary function and a high sensitising value.
30% potential water savings
10 years
3°C heat stress reduction
5 blue-green zones


The greatest positive impact created by Water on Stage is the greatly reduced consumption of drinking water (about 2 Olympic size pools per year) and a more pleasant experience on the site thanks to green-blue zones.

For Resiterra, this project serves as an inspiration for future building projects, where alternative water sources and green-blue infill can be incorporated into the plans at an early stage.

For the drinking water company De Watergroep the results of this project offer new insights into the future of decentralised water management and their potential role within this as manager of collective water systems.

Atrium.Green sees a growing need for creative, aesthetic but also functional designs of green-blue outdoor spaces. Optimisation of water management can thus be linked to a more pleasant outdoor experience, reduced heat stress and a healthier living environment.

Finally, for VITO this research project offers great added value in the further development and application of the software WaterArchitect. We can now apply this tool to future residential new construction projects.