Heating oil tank: obligations when selling

What the seller must say

The notaries’ “checklist” page is clear: for the tank there is no explicit obligation, but the seller’s general duty to inform covers the heating. Note the capacity, the location (cellar, garden, underground or above ground) and the year it was installed. If you have refill invoices or an inspection report, add them to the file: this avoids questions at the time of the sale agreement (compromis).

For the full list of documents, see the steps to sell your house.

Brussels: thresholds and obligations

Bruxelles Environnement (the Brussels environment agency) distinguishes the size and position of the tank:

• above ground, less than 3,000 litres: neither a declaration nor an environmental permit;
• underground up to 10,000 litres, or above ground from 3,000 to 10,000 litres: a declaration is required;
• more than 10,000 litres, underground or above ground: an environmental permit is needed, and the storage is treated as an activity at risk for the soil and groundwater.

The commune is the authority for classes 3 and 2, Bruxelles Environnement for class 1B. The page consulted does not detail how often inspections must take place: ask the commune or the Bruxelles Environnement Inspectorate.

Decommissioning a tank in Brussels

Before starting, send a registered letter to the competent authority with the date and a description of the works. Then:

1. if there has been a leak or an accident, have a soil investigation carried out by an approved firm;
2. empty and degas the tank, then have it cleaned;
3. have the sludge and cleaning waste removed by an approved hazardous-waste collector, who must provide traceability documents;
4. then send a copy of these documents to the commune or to Bruxelles Environnement.

For a storage of more than 10,000 litres, a soil investigation is required “no later than 6 months after the cessation” of the activity at risk.

Neutralisation

An underground tank may remain in the ground if:

• it does not hinder future soil treatment or soil monitoring;
• its filling point is made unusable so that no delivery is possible;
• it is filled with sand (particles larger than 0.05 mm) or another inert material, such as concrete.

Foam is only allowed with the authorisation of Bruxelles Environnement. A tank that is not underground may also stay in place, under the same conditions of not causing a hindrance and having its filling point disabled. Conditions specific to your declaration or permit may be added.

Wallonia: declaration, inspection and decommissioning

According to wallonie.be, a tank of 3,000 to 24,999 litres is a class 3 installation. It “must be the subject of a declaration” and comply with the conditions of the Walloon Government order of 17 July 2003. The form is available from the commune or can be downloaded from the page. Among other things, it asks for the cadastral references and a sketch of the location.

Other points:

• if you cannot prove the actual capacity (purchase invoice, refill invoice, gauging), the tank is treated as larger than 3,000 litres, and therefore must be declared and inspected periodically;
• the inspection is mandatory and carried out by a technician approved in Wallonia, freely chosen by the citizen. You can ask for a second opinion or several quotes for the works.

Decommissioning in Wallonia

When the tank is no longer used, for example after switching to mains gas: the tank is emptied, cleaned and degassed, and the sludge goes to an approved hazardous-waste collector. An above-ground tank must be removed and disposed of. An underground tank must be removed and disposed of, or made inert. The pipes are emptied, dismantled and removed.

The Walloon page also mentions a PROMAZ Fund (Fonds PROMAZ) until 28 February 2025; check with the service whether any aid exists today. For any question, the Region’s tank service can be reached via the page.

So, what should you do before selling?

• Find out the capacity, the year and the location.
• Check whether a declaration exists (commune) and whether an inspection was carried out recently. If the inspection is overdue in Wallonia, make an appointment with an approved technician.
• If the tank is unused, choose: have it neutralised according to your Region’s rules, or leave it as it is and tell the buyer clearly.
• Talk to the notary, who will draft the appropriate wording in the compromis and the deed.

Which professional to consult

An approved technician inspects the tank (Wallonia). An approved hazardous-waste collector removes the sludge. For polluted soil, an approved firm carries out the investigation. The notary handles what needs to be written in the compromis. The commune receives the declaration.