Where an oil tank is allowed to sit is decided by four things: fire separation from buildings and boundaries, the pollution risk to water, the base it stands on, and whether a tanker can actually reach it. Get any one of them wrong and the installation is non-compliant — and on a commercial site that becomes the operator’s liability, not the installer’s.
This page sets out the siting rules that apply in the UK, the distances involved, and what to do when an existing tank turns out to be in the wrong place. It covers commercial and industrial premises in particular, but the fire separation distances are the same wherever the tank sits.
Guidance, not legal advice. Requirements change and vary by nation. Always confirm against the current OFTEC technical books, Building Regulations Approved Document J and your local authority before work starts.
Fire Separation Distances
These are the minimum clearances between the tank and what surrounds it. They come from OFTEC guidance and Building Regulations Approved Document J, and they apply to plastic and steel tanks alike.
| Minimum distance | Measured to |
|---|---|
| 1.8 m | A non-fire-rated building or structure — a timber shed, a cabin, a lean-to |
| 1.8 m | Non-fire-rated eaves of a building |
| 1.8 m | Openings such as doors and windows in a fire-rated building |
| 1.8 m | The flue terminal of an oil-fired appliance |
| 760 mm | A non-fire-rated boundary — a timber fence, for example |
| 600 mm | Screening that does not form part of the boundary |
Where those distances cannot be achieved, the usual remedy is a fire-rated barrier: masonry with at least 30 minutes fire resistance, extending beyond the tank on the relevant side. That is often cheaper than moving a tank — but it has to be built correctly, not improvised.
The Base
The base carries the weight of a full tank, and on a commercial site that can be several tonnes. It must be:
- Non-combustible and imperforate — concrete, paving stones or stonework. Not gravel, not timber, not compacted soil.
- Extended at least 300 mm beyond every side of the tank, so there is a clean, level surround.
- Substantial enough for the load — commonly paving slabs of at least 50 mm on a compacted, blinded hardcore base, or concrete of at least 100 mm. Larger commercial tanks need a base designed for the actual filled weight.
- Level and fully supporting the tank. Plastic tanks in particular must be supported across the whole base, not bridged across piers.
The most common failure we are called to. A tank sitting on a base that has settled, cracked, or was never big enough. The tank distorts, the outlet stresses, and the leak starts at the lowest point — where nobody can see it.
Distance From Water, Boreholes and Drains
Pollution risk is the second half of the siting decision, and on a commercial site it carries the heavier penalties. Government guidance is that a tank should not be sited outside a building:
- within 10 metres of inland fresh waters or coastal waters — a river, stream, pond, ditch or a drain that reaches them;
- within 50 metres of a well, spring or borehole.
Groundwater Source Protection Zone 1 is treated as higher risk again. Where a tank has to sit inside those distances, expect to need more than the minimum: full secondary containment, a sealed and contained base, and in some cases a monitored bund.
Commercial Premises: The 200-Litre Rule
This is where commercial siting parts company with domestic. Under the Control of Pollution (Oil Storage) (England) Regulations 2001, oil stored above ground at industrial, commercial and institutional premises — offices, shops, schools, hospitals, garages, depots, nursing homes, and blocks of flats with communal storage — must meet the containment requirements once capacity exceeds 200 litres.
A private dwelling storing 3,500 litres or less purely for its own heating sits outside those regulations. Almost every commercial tank sits inside them.
What the containment has to hold
- One tank: the bund must hold at least 110% of the tank’s capacity.
- Several tanks in one bund: whichever is greater — 110% of the largest tank, or 25% of their combined capacity.
- Drums: a drip tray holding at least 25% of the drum capacity, or 25% of the aggregate where there are several.
- The bund must be impermeable to oil and water with no drain through it, and fill points, gauges, valves and vents must sit within it.
An integrally bunded tank satisfies this without a separate structure, which is why almost every replacement commercial tank is specified that way — see commercial fuel tank installation.
Access, Deliveries and Site Traffic
Compliance decides where a tank may go. These decide where it should go — and they are the reasons sites end up paying to move a tank a second time.
- Tanker reach. A delivery hose has a finite length. If the tanker cannot get within reach of the fill point, every delivery becomes a problem, or an overfill risk from a stretched, unsupervised run.
- Impact protection. On a yard or depot the tank needs protecting from forklifts, reversing HGVs and trailers — bollards or a barrier, positioned so they do not themselves breach the separation distances.
- Visible fill point. Overfills happen when the driver cannot see the gauge or hear the alarm.
- Room to work. Inspection, cleaning and eventual removal all need access around the tank. A tank boxed in by later construction becomes far more expensive to service or take out.
- Security. Fuel theft is a real cost. Lockable fill points and cabinets, and a position that is overlooked rather than hidden behind a building.
- Future development. If an extension, a new unit or a yard reconfiguration is planned, site the tank where it will still be compliant afterwards. Separation distances are measured to whatever gets built, not to what stood there on installation day.
If the Tank Is Already in the Wrong Place
Most siting problems we are called to are inherited — a tank installed under older rules, or a building put up next to a tank that was compliant when it went in. The options, cheapest first:
- Build a fire-rated barrier. Where the shortfall is separation distance to a structure or boundary, a correctly built masonry wall usually resolves it without touching the tank.
- Move the screening. A trellis or fence within 600 mm of the tank is a straightforward fix.
- Re-base the tank. Where the base has failed but the tank is sound, the tank can be lifted, the base rebuilt and the tank reinstated.
- Add secondary containment. A single-skin tank near water can be brought into line with a constructed bund, or replaced with an integrally bunded unit.
- Relocate the tank. Drain, clean, gas-free, lift, re-site on a new base and recommission — see tank relocations and project-managed works.
If a leak has already reached the ground, siting is no longer the first problem — see oil spill response and contaminated land remediation. For who carries the legal duty on a commercial tank, see oil tank owner responsibilities.
Scotland, Wales and Northern Ireland
The fire separation distances are broadly consistent across the UK, but the oil storage legislation is not. Scotland, Wales and Northern Ireland each have their own regulations and thresholds, and Northern Ireland in particular treats domestic storage differently. Check the rules for the nation the site is in rather than assuming the England position applies.
Domestic Tanks
The separation distances above apply to a home heating oil tank too. If you are a homeowner rather than a business, our sister company LV Fuel Services covers the domestic OFTEC requirements and handles domestic tank work directly.
Not Sure If Your Tank Is Compliant?
Tell us the tank size, what is around it, and how close the nearest drain or watercourse is. We will tell you where it stands — and whether it needs a barrier, a bund, a new base or a move.
