VerticalBunded Oil Tanks

A bunded tank has an integral outer skin that holds at least 110% of the inner tank's capacity, so any leak or overfill is contained rather than escaping into the ground. Building regulations and OFTEC guidance require bunding wherever there's a meaningful risk of oil reaching a watercourse, drain, or where the tank sits within 10 metres of water, or where storage exceeds certain volumes for commercial premises. In practice, most domestic and trade heating oil installations now specify bunded as standard.

Vertical tanks have a smaller footprint, which is useful where garden, yard or plant room space is tight, and they're often easier to site against a wall or in a corner. They typically suit properties needing higher storage capacity without extending the installation lengthways. The trade-off is a taller unit, so headroom and visual impact need checking before you order.

For an average household, 1,200 to 1,300 litres covers roughly a year's heating oil, but usage varies with property size, insulation and how much hot water you use. Larger homes or those running oil-fired Agas alongside heating often move up to 1,800–2,500 litres to reduce delivery frequency. If you're also storing diesel for machinery or generators on a trade site, size for peak demand plus a comfortable reserve rather than cutting it fine.

OFTEC guidelines set minimum separation distances from boundaries, buildings, openings and eaves — typically 1.8 metres from a non-fire-rated wall or window, reducing to 0.6 metres if a suitable fire-rated barrier is used. The tank also needs to sit on a firm, level, non-combustible base such as concrete or paving slabs rated for the filled weight. Always check current OFTEC/Building Regulations Part J requirements for your specific site, as rules differ for oil versus other fuels.

Most domestic bunded oil tank installations are permitted development and don't need planning permission, provided the tank stays under the volume and height thresholds and isn't sited in front of the property. Installation must still be carried out or certified by an OFTEC-registered technician, who will notify Building Control on your behalf. Commercial or larger-capacity installations may need separate planning consideration, so it's worth checking with your local authority beforehand.

Steel bunded tanks are robust and well suited to commercial or higher-capacity installations, though they need periodic checks for corrosion over their service life. Polyethylene (plastic) bunded tanks are lighter, won't rust, and are generally lower maintenance, making them the more popular choice for domestic heating oil storage. Both are widely available in vertical format — the right choice usually comes down to site access, budget and expected lifespan rather than performance differences for typical use.