Bonus for water and biodiversity projects

The City supports you financially if you perform at least one, or a combination of the following actions:

1. Removal of paving and permeability of the subsoil

This action involves removing impermeable and semi-permeable pavement (tiles, concrete, asphalt, foundation) and possibly replacing it with earth to facilitate the infiltration of rainwater into the soil of a site/plot.

2. Installation of a green roof

This action covers the installation of an extensive, a semi-intensive or an intensive green roof.

An extensive green roof or vegetation roof is a green roof with a substrate thickness of 5 to 10 cm, with a weight of between 30 and 100 kg/m² due to thin support layers and light rooting plants. This type of green roof is particularly suitable for flat roofs and can be installed on existing buildings with a few modifications.

A semi-intensive green roof is a green roof with a substrate thickness of 10 to 30 cm, weighing between 100 and 400 kg/m². Shrubs and small bushes can grow on this type of green roof, in addition to the muscle and herb layer that can already develop on an extensive roof.

An intensive green roof or garden roof is a green roof with a substrate thickness of more than 30 cm, consisting of deep-rooted plants, which often requires an adapted roof, as well as a reinforcement of the building structure because a thick layer of soil is required (overweight more than 400 kg/m²).

3. Reusing rainwater from your roof

This action covers the installation, repair or replacement of rainwater harvesting systems from one or more roofs (for example underground tanks).

4. Letting rainwater infiltrate into the soil

This action concerns the installation of an infiltration system or a set of linked or separate open-air infiltration systems that allow water to percolate into the ground, including the drainage and storage structures connected to it.

It can take the form of wadis, vegetated wadis, dry or wet basins, infiltration channels, rain gardens with water ladders or infiltration pits. Different systems can be combined to optimise infiltration. Sinks are excluded from the premium.

5. Bonus biodiversity

For actions 1, 2 and 4 you can get another bonus if you plant the areas with biologically valuable and indigenous plants.

Wondering what exactly these actions entail? You will find many examples further down this page.

The City of Brussels gives you financial support if you want to carry out one of the above actions separately or several together.

For example, you are eligible for a premium if you only want to install a green roof or if you only want to infiltrate rainwater from your roof.

However, you are encouraged to be ambitious and combine the different interventions.

For example, you can install a cistern, whose overflow is taken to an infiltration zone for infiltration. Or you can connect a green roof to an infiltration ditch. In this way, you are eligible for the cumulative amount of the interventions for which the City provides financial support.

The maximum amount you can receive per project for a single action or for several actions together is 10,000 euros. The exact amount you can receive per project is further limited by:

• The total amount of the investment made (as you only get back what you invest)
  All investments, excluding study costs, that you have made to realise the above actions on your plot are eligible to obtain the premium, for example:
  • the working hours of contractors for the construction of the facilities
  • the purchase of materials and plants for the facilities
  • hire of working equipment for the construction of the facilities
  • removal of soil cover to enable infiltration
• The premium calculation (83.53 KB) based on the number of m² realised for the various actions (the more ambitious your project is, the higher the premium will be)

An extra bonus of 5 euros/m² can be granted if the application meets one of the following conditions:

• if the works are carried out in their entirety by a social economy enterprise, customisation enterprise or social inclusion enterprise
• or if the facilities are realised for a house intended for rental (owner is not domiciled in the property) for a period of at least 5 years

Examples for calculations

Examples for calculations (115.53 KB) (in French)

Special conditions

To benefit from the premium, a number of conditions must be met in the actions you carry out to ensure the quality of the installations. Be sure to read the regulations carefully.

In the document below you will find the invasive plant species (may not be planted!), the indigenous plant species and the plant species recommended for the various actions:

• Indigenous and recommended plant species (527.92 KB) (Bruxelles Environnement, in French)
• Annex premium - plant list (365.38 KB) (in French)

Practical examples and inspiration

Practical examples and inspiration (867.07 KB) (in French)

Have an ambitious project in mind but don't know how to get started? From January 2025, the City of Brussels will offer you a professional guidance service that will:

• make a diagnosis of your site and analyse the possibilities for reuse and infiltration of rainwater
• draw up a design for your project, helping you to map out the actions, dimension the installations and determine the connections and surface areas

Please note that you must disconnect at least 100 m² of roof area and paved area from the sewerage system to benefit from this guidance service.

If you meet this minimum condition, contact the Climate and City in Transition service, which will refer you to the support service. If you do not meet this minimum condition, the Climate and City in Transition service will guide you in your project development on its own.

Under certain conditions and with the consent of the City of Brussels, the guidance service will also take responsibility for the permit application, checking contractors' offers and submitting the premium application. The latter is only for very ambitious projects of a disconnection of more than 750 m² of roof area and paved surface from the sewerage system. This is possible for companies, associations and schools, for example.

To perform the actions, you may of course always work with a professional, but this is not compulsory. So you can carry out the actions all by yourself, saving a lot of money.

If you also want a green roof, it is advisable to work with a professional because of the complexity these works can sometimes involve.

In addition, if you want to store rainwater in an underground cistern, however, you are required to contact a professional for this. 

• Do-It-Yourself (7.56 MB) (in French)
• Do-It-Yourself guide (1.90 MB) (Brusseau, in French and Dutch)

Complete the municipal premium application form (1,015.31 KB) and send it, together with the required documents, to urb.primes@brucity.be within 3 months of the end of the works.

• By phone on 02 279 33 10
• By e-mail to urb.primes@brucity.be