If you store oil, fuel or chemicals in an IBC, one of the first questions you’ll be asked is “is it bunded?” A bund (also called a spill pallet or secondary containment) sits under the IBC and catches anything that leaks. Getting the size right matters: too small and it won’t contain a failure, and for oil it may not meet the law.
This guide explains how to work out what size bund you need for one or more IBCs, what the UK oil storage regulations say, and how to choose the right IBC bund for your site. New to bunds? Start with our guide What is an IBC bund?
The short answer
For a single IBC, the bund must hold at least 110% of the IBC’s capacity. A standard 1,000 litre IBC therefore needs a bund of at least 1,100 litres.
Where several containers share one bund, it must hold whichever is greater: 110% of the largest container or 25% of the total capacity stored on it.
Why 110%?
The extra 10% gives a margin above the full contents of the container. It allows for rainwater already sitting in an outdoor bund, foam or surge when a container fails suddenly, and the volume taken up by the IBC’s own cage, pallet base and any decking grid sitting in the sump.
Working out your bund size: worked examples
| What you’re storing | Calculation | Minimum bund capacity |
|---|---|---|
| 1 x 1,000 litre IBC | 110% of 1,000 | 1,100 litres |
| 1 x 1,250 litre IBC | 110% of 1,250 | 1,375 litres |
| 2 x 1,000 litre IBCs on one bund | Greater of 110% of 1,000 (1,100) or 25% of 2,000 (500) | 1,100 litres |
| 4 x 1,000 litre IBCs on one bund | Greater of 110% of 1,000 (1,100) or 25% of 4,000 (1,000) | 1,100 litres |
| 6 x 1,000 litre IBCs on one bund | Greater of 110% of 1,000 (1,100) or 25% of 6,000 (1,500) | 1,500 litres |
As the table shows, a twin IBC bund doesn’t need to hold 2,200 litres. The rule assumes that one container failing is the realistic worst case, so the 110% figure is based on the largest container, unless the 25% figure is larger.
One exception: if containers are connected together (for example, linked with pipework so the contents can flow between them), they are treated as a single container. The bund then needs to hold 110% of their combined capacity.
What do the UK oil storage regulations say?
In England, the Control of Pollution (Oil Storage) (England) Regulations 2001 apply to businesses and public buildings storing oil in containers of 201 litres or more. The GOV.UK guidance on oil storage lists IBCs, along with oil drums, fixed tanks and mobile bowsers, as containers covered by the rules. As every standard IBC is well over 201 litres, an IBC of oil at a business site will normally need secondary containment.
“Oil” covers more than you might think, including:
- Diesel, petrol and biofuels
- Kerosene and heating oil
- Vegetable oils and hydrotreated vegetable oil (HVO)
- Synthetic, solvent and lubricating oils
- Cutting fluids and insulating oils
- Waste cooking and vegetable oil
The capacity rules are 110% for a single container, and the greater of 110% of the largest or 25% of the total for multiple containers. The bund must also be impermeable, have no drain valve or outlet, and contain the container’s taps and valves so that drips from dispensing are caught too.
The guidance includes some exemptions, such as oil stored inside a building that would capture any leak. Always check the current guidance for your situation.
Wales, Scotland and Northern Ireland
- Wales: the Water Resources (Control of Pollution) (Oil Storage) (Wales) Regulations 2016 use the same 110% / 25% capacity rules.
- Scotland: oil storage is regulated by SEPA. Since 1 November 2025, this has been under the Environmental Authorisations (Scotland) Regulations 2018. Containers of 200 litres or more need secondary containment holding 110% of the container, or for several containers the greater of 110% of the largest or 25% of the total.
- Northern Ireland: the Control of Pollution (Oil Storage) Regulations (Northern Ireland) 2010 cover containers of more than 200 litres, including IBCs, with the same 110% / 25% capacity rules.
Farms storing agricultural fuel oil have separate rules in each nation.
What about chemicals and other liquids?
The oil storage regulations apply specifically to oil. Many other liquids, such as acids, alkalis, solvents, cleaning chemicals, AdBlue and food liquids, aren’t covered by those exact rules. They can still cause serious pollution, harm and clean-up costs if they leak, though.
The 110% / 25% rule is widely used as the benchmark for chemical storage too. Your environmental permit, risk assessment, insurer or customer may require it. If in doubt, size your bund using the same calculation.
For chemicals, also check that the bund material is compatible with what you’re storing. Polyethylene suits a wide range of chemicals, but not all. Also keep incompatible substances (for example, acids and alkalis) on separate bunds.
Choosing the right IBC bund
Once you know the capacity you need, consider:
- Number of IBCs: single or twin IBC bunds are the most common. A twin bund can be more space-efficient than two singles.
- Indoor or outdoor use: outdoor bunds collect rainwater, which reduces the capacity available for a spill. A covered IBC spill pallet keeps rain out, so the full sump stays available.
- Dispensing: if you fill containers from the IBC tap, a bund with an integral dispensing area catches drips at the point of use.
- Forklift access: two-way or four-way fork pockets make it easier to move the bund once it’s empty.
- Material: polyethylene bunds are corrosion-free and suit many chemicals. Steel bunds offer high strength for some oils and fuels.
IBC bunds from ITP Packaging
Our IBC spill pallets are designed to the 110% / 25% capacity rule and include:
- IBC Spill Pallet with 1,125 litre sump: suits a single 1,000 litre IBC.
- IBC Spill Pallet with 1,260 litre sump: extra margin over the 1,100 litre minimum.
- IBC Spill Pallet for 2 IBCs: 1,140 litre polyethylene sump with a removable grid, for two 1,000 litre IBCs.
- Covered IBC Spill Pallet 1,100 litre: for outdoor storage.
Storing drums as well as IBCs? See our drum spill pallets and drip trays. For drums used with a drip tray, the tray only needs to hold 25% of the drum’s capacity.
Keeping your bund effective
- Inspect it regularly for cracks, damage or corrosion.
- Remove rainwater promptly, and dispose of contaminated water correctly.
- Never fit a drain valve to an oil bund.
- Don’t use the sump for storage. Anything inside it reduces the capacity.
- Keep an oil spill kit or chemical spill kit nearby for spills outside the bund, such as when filling or dispensing.
Frequently asked questions
What size bund do I need for a 1,000 litre IBC?
At least 1,100 litres (110% of the IBC’s capacity).
What size bund do I need for two IBCs?
For two 1,000 litre IBCs on one bund, at least 1,100 litres. That’s 110% of the largest container, which is greater than 25% of the 2,000 litre total. If the IBCs are linked together, the bund must hold 110% of the combined 2,000 litres (2,200 litres).
Is a bund a legal requirement for an IBC?
If you store oil in an IBC at a business or public site in the UK, secondary containment is normally required by law (subject to the exemptions in the regulations). For other liquids it is strongly recommended, and it may be required by your permit, risk assessment or insurer.
Can I use a drip tray instead of a bund for an IBC?
No. Drip trays sized at 25% are only permitted for drums. An IBC needs secondary containment of at least 110% of its capacity.
What happens if I don’t comply?
The environmental regulator can serve a notice requiring you to bring your storage up to standard, and you could be fined or prosecuted. You could also be liable for the cost of cleaning up any pollution.
This guide is a general summary to help you choose suitable containment. It isn’t legal advice. Always check the current regulations and guidance from the Environment Agency, Natural Resources Wales, SEPA or NIEA for your circumstances. Need help choosing a bund? Contact our team.
