Oil tank — maintenance, inspection, and regulations
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Post a job — we'll find you an engineer →⚠️ Oil spills from domestic tanks cause significant environmental damage and can result in prosecution and liability for clean-up costs, which can exceed £10,000. A leaking tank must be taken out of service immediately.
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Most likely cause & what to check
Domestic heating oil tanks (usually 1,000–3,500 litres) are regulated by Building Regulations Part J and the Oil Firing Technical Association (OFTEC) standards. Single-skin steel tanks older than 20 years should be replaced — they corrode internally and can fail without warning.
Check the tank monthly for signs of leaks — staining on the ground beneath it, strong oil smell, or oil sheen on any nearby drainage. Check the vent pipe (a small pipe on top of the tank) is clear — a blocked vent creates a vacuum and can cause the tank to collapse when oil is drawn out.
Inspect the fuel gauge — most tanks have either a sight glass gauge (glass tube on the side showing level) or a float gauge (dial on top). Sight glasses crack over time and can be a significant leak source. Check it is clean and intact.
The oil supply pipe from the tank to the boiler should be either buried (minimum 50mm depth) or run in a proprietary fire-resistant duct where it crosses paved areas. A fire valve (a thermal cut-off valve on the supply line near the boiler) is a regulatory requirement — check it is present and not corroded shut.
If your tank is above ground and holds more than 2,500 litres (or is within 10 metres of a watercourse or 50 metres of a borehole), secondary containment (a bunded tank or a bund wall) is required by UK regulations. Single-skin tanks above these thresholds are now non-compliant.
Annual oil tank servicing by an OFTEC technician costs £50–£100 and covers internal inspection, filter cleaning, testing of the fire valve, and checking the tank condition. This should be done at the same visit as the boiler service.
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