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Rainwater pit obligation in Tervuren: what you must know

  • Writer: Eutradesmen
    Eutradesmen
  • a few seconds ago
  • 6 min read

Installing infiltration bed beside rainwater pit

Yes, a rainwater pit (hemelwaterput) is mandatory for most new builds, rebuilds, and many renovations in Tervuren. The Hemelwaterverordening 2023 (GSV hemelwater), in force since 2 October 2023, sets the core obligation across Flanders. Tervuren enforces this regional rule and may layer on stricter local requirements. If you are planning any building work that changes your drainage or increases impermeable surface area, you almost certainly need a compliant system in place before you move in.

 

What triggers the obligation?

 

  • New build or full rebuild

  • Major renovation that alters drainage or roofing

  • Extensions that increase impermeable surface (driveways, terraces, patios)

  • Significant works on hard surfaces (verhardingen)

 

Your immediate next steps:

 

  1. Check your permit documents for a hemelwater plan and volume calculation.

  2. Confirm whether addendum B25 is required on your dossier.

  3. Contact the Tervuren planning team (Bouwen en verbouwen) with any questions.

  4. Book an on-site check with Eutradesmen if you are unsure whether your current system is compliant.

 

The system must be in use at occupancy (ingebruikname). That means it must be connected to at least one internal take-off point, such as a toilet, washing machine, or service tap, before you legally occupy the building. An installed but unconnected tank does not satisfy the Vlaanderen guidance on mandatory installation.

 

Table of Contents

 

 

Key things every Tervuren homeowner must remember

 

The GSV 2023 technical document and regional legal excerpts set out the sizing rules clearly. Here is what matters most:

 

Point

Details

Minimum volume (single-family)

The minimum tank size is 5,000 l for a single-family home. This rises to 7,500 l for roof areas of 80–120 m² and 10,000 l for 120–200 m², with a formula-based calculation required above 200 m².

Large buildings

Use a formula-based calculation above 200 m² roof area as outlined in the technical document

Overflow connection

Overflow must go to an infiltration or buffer provision, never to the mixed sewer

In-use rule

System must be operational and connected at occupancy, not just installed

Permit dossier

Show pit volume, take-off points, and overflow route on plans; include B25 addendum if required

Additional points to keep in mind:

 

  • The Codex Vlaanderen policy framework ranks obligations in order: reuse first, then infiltration, then buffering, then discharge. Your plans must show how reuse and infiltration will be achieved.

  • Exemptions exist for small plots or properties with extensive green roofs, but they are not automatic. You must consult the municipality and provide technical proof.

  • Tervuren can set rules stricter than the regional minimum. Always verify locally.

  • A mandatory secondary circuit inspection (keuring) is required before household use to prevent cross-contamination between rainwater and drinking water pipes.

  • Non-compliance can delay permits and complicate future property sales.

 

Our honest view from working in Tervuren

 

Eutradesmen works regularly on installations and compliance checks across Brussels, Tervuren, Waterloo, and Leuven, and the same problem comes up repeatedly: a pit that was installed years ago but never properly connected or maintained.

 

One recent Tervuren job is a good example. A homeowner had a 5,000 l tank buried in the garden, but the overflow ran straight to the combined sewer and the toilet was still on mains water. The garden was waterlogged every winter because the infiltration crates had never been installed. The fix involved rerouting the overflow to a proper infiltration bed, connecting the toilet and a garden tap to the secondary circuit, and clearing the gutters and filter basket that had been blocked for two seasons. After the work, the garden drained properly, the household water bill dropped, and the dossier was ready for the permit check.

 

That kind of job touches several trades at once: a plumber to connect the internal circuit and prepare for the keuring, a gardener to install and landscape the infiltration bed, and a handyman to handle the smaller works. Getting one English-speaking team to coordinate all of it saves a lot of time and confusion, especially if Dutch paperwork is not your first language.

 

Pro Tip: Keep a maintenance log for your hemelwaterput. Clean the filter basket at least twice a year, check the pump annually, and photograph the overflow route. Inspectors and future buyers will ask for it.

 

How Eutradesmen can help you stay compliant


Eutradesmen

Sorting out a rainwater pit in Tervuren involves more than digging a hole. Eutradesmen offers a fully coordinated service covering every stage: site survey and drainage calculations, installation of the pit and infiltration crates, plumbing connections for internal take-off points, help with permit documents and the B25 addendum, and inspection preparation for the mandatory keuring.

 

The team is English-speaking, experienced with Tervuren’s local requirements, and brings together plumbers, gardeners in Tervuren, and electricians for pump power supply under one coordinated job. No chasing three separate contractors or deciphering Dutch permit forms on your own.

 

Whether you need a full new installation, a compliance check on an existing system, or just someone to tell you honestly what your dossier is missing, Eutradesmen can visit the site and give you a clear, transparent quote. With 20+ years of experience across Brussels, Tervuren, Waterloo, and Leuven, the team knows exactly what local inspectors expect to see.

 

Get in touch today for a free compliance survey.

 


How Eutradesmen can help you stay compliant — overview diagram

Useful official documents and local contacts for your dossier

 

Use this list when assembling your permit dossier or preparing for an inspection:

 

Document

What it covers

Where to find it

Hemelwaterverordening 2023

Core legal obligation, in-use rule, reuse/infiltration hierarchy

Departement Omgeving

Vlaanderen.be guidance

Triggers, exemptions, required take-off points

Vlaanderen.be

GSV 2023 technical document

Minimum volumes, infiltration sizing formulae

Integraal Waterbeleid

FAOLEX legal excerpts

Precise legal wording on volumes and overflow connection

FAO

Codex Vlaanderen

Policy rationale and reuse-first hierarchy

Codex Vlaanderen

Parliamentary dossier (B25)

Permit dossier expectations, B25 addendum, take-off points on plans

PMG viewer

Housing Service practical guide

Homeowner-friendly volume summary and common pitfalls

Housing Service

Tervuren Bouwen en verbouwen

Local contact point for permits and dossier submission

Tervuren municipality

What to show on your plans:

 

  • Pit volume calculation (with roof area used as the basis)

  • All take-off points (toilet, washing machine, service tap) clearly marked

  • Overflow route from the pit to the infiltration or buffer provision

  • Infiltration surface or buffer volume calculation

  • B25 addendum attached if your permit form requires it

 

FAQ

 

Is a rainwater pit always required in Tervuren?

 

For new builds and full rebuilds, yes. Many renovations and extensions that increase impermeable surface also trigger the obligation under the Hemelwaterverordening 2023. Exemptions exist for small plots or extensive green roofs but must be formally approved by the municipality.

 

What is the minimum tank size for a house in Tervuren?

 

The baseline is 5,000 l for a single-family home. This rises to 7,500 l for roof areas of 80–120 m² and 10,000 l for 120–200 m², with a formula-based calculation required above 200 m².

 

Can the overflow go to the normal sewer?

 

No. The GSV 2023 requires overflow to connect to an infiltration or buffer provision, not the mixed sewer. Showing this route on your plans is a permit requirement.

 

What happens if my system is installed but not connected?

 

An unconnected tank is treated as non-compliant. The law requires effective reuse through at least one internal take-off point. This can delay your permit sign-off and cause problems at property sale.

 

Who can help me with the paperwork and installation in Tervuren?

 

Eutradesmen handles the full process: site survey, installation, internal plumbing connections, and permit dossier support, all in English. Contact the team for a free quote.

 

Ready to solve your issue? WhatsApp +32 466 900 281 for a free quote today!

 

Contact Eutradesmen

 

WhatsApp: +32 466 900 281 Telephone: +32 2 808 70 31 Email: info@eutradesmen.com

 

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