Bunded Storage Solutions
Bunded storage (also called secondary containment) is a practical way to reduce risk when storing liquids such as oils, fuels, coolants, solvents and chemicals. Put simply, you store the container on or inside a liquid-tight “bund” (for example a bunded pallet, covered bund, IBC bund, spill tray or portable berm) so that if the primary container leaks, the spill is captured and controlled instead of spreading across floors or reaching drains and the environment.
In cleanrooms and controlled environments, bunded storage also supports housekeeping and contamination control by keeping drips contained at source and making safe response easier when you pair storage with the right spill kits, pads and procedures.
Why bunded storage matters
- Safety: helps prevent slip hazards and uncontrolled pooling around drum taps, valves, pumps and decant points.
- Environmental protection: reduces the chance of liquids escaping to drains, yards or watercourses.
- Compliance: UK guidance and regulators commonly reference secondary containment (bunds/drip trays) as a key control measure for oil and other polluting liquids.
- Operational efficiency: spills are easier to isolate, clean and document when the leak is already contained.
What counts as bunded storage
Secondary containment can take several forms depending on what you store and how you handle it. The most common options include bunds and drip trays, with the choice typically driven by container type and usage patterns (static storage vs decanting vs mobile use).
- Bunded pallets (spill pallets): raised platforms with an integrated sump, used for drums and small containers.
- IBC containment (bunded IBC pallets): designed for 1, 2 or more IBCs, with high-capacity sumps.
- Covered bunds and stores: bunded units with weather protection and security for external storage areas.
- Bunded drum trays and drip trays: low-profile containment for small leaks and day-to-day drips during handling/decanting.
- Portable bunding and berms: flexible containment for temporary work zones, maintenance tasks or where fixed bunds are impractical.
Capacity and sizing rules of thumb
Secondary containment is commonly sized using simple capacity benchmarks. For multiple containers, UK guidance often references either:
- 110% of the largest container, or
- 25% (one quarter) of the total combined container volume,
whichever is greater (with additional considerations where containers are linked or where fire-fighting water retention is required). For drums, guidance also commonly references a drip tray capacity of at least one quarter of the drum volume (and one quarter of combined volume if the tray is designed to hold multiple drums).
You should always validate requirements against your site risk assessment, the substances stored (including incompatibilities), where the storage sits (internal/external), drainage risk, and any specific regulatory or insurer expectations.
Choosing the right bunded storage solution
Use the checklist below to select a bunded storage setup that suits your site and the liquids you handle.
1) Identify what you are storing
- Container type: drums, jerrycans, kegs, IBCs, small bottles, process containers.
- Liquid type: oil/fuel, coolant, solvents, acids/alkalis, cleaning chemicals.
- Compatibility: ensure bund material is suitable for the chemical (and that mixed storage does not create incompatibility risks).
2) Map how liquids are handled
- Static storage only: focus on sump capacity, durability and inspection access.
- Decanting/dispensing: prioritise containment around taps, pumps and funnels (often bunded drum trays help here).
- High-traffic areas: consider low trip-risk profiles, clear labelling and good access for cleaning.
3) Consider the environment
- External storage: covered bunds reduce rainwater ingress and help keep containment capacity available.
- Cleanrooms: select solutions that support housekeeping, wipe-down routines and controlled storage practices.
- Drain proximity: if there is any pathway to drains, bunding plus drain protection and a spill response plan is strongly recommended.
How bunded storage fits your spill kit strategy
In your “Kit Strategy”, bunded storage solutions sit alongside chemical spill kits and lint-free absorbents as a preventive control. Used together, they help you:
- Reduce the likelihood of a spill spreading beyond the immediate storage/handling point.
- Shorten response time because the leak is already contained.
- Improve consistency in clean-up by keeping spills localised and easier to assess.
- Maintain higher standards in sensitive areas (including cleanrooms) by separating storage controls from clean-up controls.
Good practice is to pair bunded storage with clearly positioned spill kits, a restocking routine, and tamper seals where you need kit integrity (for example in shared spaces or regulated areas).
Inspection, housekeeping and maintenance
Bunded storage only works if it is kept serviceable. Build these steps into routine checks:
- Check sumps are empty and available (especially for outdoor units where rainwater can reduce free capacity).
- Inspect for cracks, chemical attack, warping, blocked grates, or damaged pallets.
- Verify containers are stable, upright and correctly placed within the bund footprint.
- Keep dispensing points over containment and clean drips promptly using suitable absorbents.
- Document checks in a simple log for audit readiness.
Related Serpro categories
Explore practical options depending on your containers and work areas:
- Spill Containment
- IBC Containment
- Covered Bunds and Pallets
- Drip and Spill Trays
- Bunded Drum Trays
- Spill Kits
- Chemical Spill Kits
Sources and guidance
The following references are widely used for understanding secondary containment and good practice in the UK: