No sewer in your street? First check the plot's wastewater treatment regime, then the actual installation and the obligations for the house. The absence of a network does not automatically require an individual treatment plant. A tank in the garden does not prove that discharges comply with the rules either.
Which regime applies to your plot?
Consult the SPGE's PASH maps. The PASH is the wastewater treatment plan for each river sub-basin. It places the plot under a collective, autonomous or transitional regime. The SPGE states that the accuracy, currency and completeness of the mapping information are not guaranteed: ask the municipality or the competent wastewater authority to clarify any ambiguity.
The map guides your research; it does not establish the actual connection or the house's compliance. A plot can fall under the collective regime even if the street does not yet have a sewer.
When is individual wastewater treatment compulsory?
The Walloon Water Code, articles R.275 and R.277 to R.282, distinguishes the regimes and their obligations.
Under the autonomous regime, compare the construction of the house with the date the area was first classified as autonomous by the PCGE, the former general municipal sewerage plan, or the PASH. A house built after that classification must in principle have an approved individual wastewater treatment system, or SEI, unless the competent authority has granted an exemption on the basis of a technical dossier. For an older house, also check alterations covered by planning permission that increase the pollution load, zone studies and individual decisions. The municipality can require an SEI to address a public health problem or a significant environmental impact, following the prescribed procedure.
Under the collective regime, connection to the existing sewer is compulsory in principle and requires prior written municipal authorisation, subject to the prescribed exceptions. Where there is no sewer or no collective treatment plant downstream, specific requirements apply to new houses. The transitional regime also has its own rules. Do not order a treatment plant solely because there is no sewer in the street.
The official SPW procedure for installing an SEI explains the situations concerned and the applicable environmental declaration or permit.
How can you document the existing installation?
Our method separates what is proven, what is reported and what remains to be examined. Look for:
- the drainage plans for wastewater and rainwater;
- the model, capacity and approval reference of the reported SEI;
- the invoices, applicable declaration or permit and inspection reports;
- the maintenance contracts and reports, together with evidence of emptying;
- municipal correspondence, notified obligations and individual exemptions;
- the CertIBEau and its findings, if one has been issued.
This list helps prepare the file; it is not a universal legal list of documents required for a sale. An invoice for a septic tank documents a piece of equipment, not the entire drainage route or authorisation to discharge. Recent emptying does not replace the other checks.
If the drainage route remains unknown, ask a competent professional to define a diagnostic assignment. Request a quotation separating investigation, access to the installations and any building work. No reliable cost can be given without knowing the installation and how accessible it is.
What should be clarified before building work or a sale?
Before building work, have the solution and necessary authorisations confirmed by the municipality or the competent authority. Before a sale, present the documents, known defects and open questions to the notary. Have the agreed work and the allocation of its costs clarified before the sales agreement (compromis).
According to the situations covered by CertIBEau, selling an existing building without a new drinking water connection does not, in itself, make certification compulsory. A new connection can, however, trigger this obligation, including for an old building, under the framework applicable since 1 June 2021. A voluntary inspection can document the situation; read its findings, not just its title.
Our guide to preparing the sale of your house in Wallonia places this research within the stages of your property project.
What are the answers to frequently asked questions?
Is a septic tank enough?
Not to establish compliance. Identify the complete system, the drainage route and the requirements for the house.
Does an old house always need an SEI?
No. The regime, the date of the first classification, alterations and specific decisions must be examined together.
Does the absence of a CertIBEau automatically prevent a sale?
No. A sale alone does not trigger the obligation for an existing building without a new connection. The other wastewater treatment obligations must still be checked.
Preparing a sale? Request your valuation report to put your project in context. Technical diagnosis and confirmation of the obligations remain the responsibility of the competent professionals and authorities.
