Complete Guide to COSHH Compliance for Hazardous Substance Storage

Last updated: April 2026

The Control of Substances Hazardous to Health Regulations 2002 (COSHH) represent the primary legislative framework governing the storage, handling, and use of hazardous substances in UK workplaces. Whether you store oils, solvents, cleaning chemicals, or industrial fluids, COSHH compliance is not optional — it is a legal duty enforced by the Health and Safety Executive (HSE) with serious consequences for non-compliance.

This guide covers everything UK businesses need to know: what COSHH actually requires for hazardous substance storage, how to conduct a compliant risk assessment, secondary containment rules including the 110% bund rule, documentation obligations, inspection requirements, and the penalties your business faces if you fall short.

What Are COSHH Regulations and Who Do They Apply To?

COSHH Regulations 2002 (SI 2002/2677), made under the Health and Safety at Work etc. Act 1974, apply to virtually every UK employer who uses or stores substances that are hazardous to health. A "substance hazardous to health" covers an enormous range of materials including:

• Chemicals classified as toxic, very toxic, harmful, corrosive, or irritant under the Classification, Labelling and Packaging (CLP) Regulation
• Carcinogens and mutagens
• Biological agents capable of causing disease
• Dusts in concentrations exceeding Workplace Exposure Limits (WELs)
• Any substance with a WEL listed in EH40
• Pesticides, solvents, fuels, lubricants, cleaning products, and process chemicals

There is no minimum threshold for compliance — even small businesses storing a handful of chemicals must comply fully with the Regulations.

The Eight Core Duties Under COSHH

COSHH Regulation 7 places a clear hierarchy of control on employers. For storage specifically, the primary duties are:

1. Elimination or substitution — can the hazardous substance be replaced with something safer?
2. Engineering controls — enclosed storage, secondary containment (bunding), ventilation
3. Administrative controls — procedures, training, reduced quantities stored
4. Personal protective equipment (PPE) — gloves, goggles, chemical-resistant suits

Secondary containment — bunded pallets, spill bunds, and drip trays — falls squarely within engineering controls and is often the most practical and cost-effective compliance measure for chemical storage.

COSHH Risk Assessment: A Step-by-Step Approach

Regulation 6 requires a suitable and sufficient assessment of the risk created by work involving substances hazardous to health before that work begins. For storage, this means:

Step 1 — Identify the substances

Create a complete chemical inventory. Obtain Safety Data Sheets (SDS) for every substance — these are required under REACH Regulation (EC) 1907/2006 and must be no older than three years. Sections 2 (hazard identification), 7 (handling and storage), and 8 (exposure controls) are critical.

Step 2 — Assess the risk

Consider the quantity stored, frequency of access, physical state (liquid, solid, vapour), flash point and flammability, proximity to drains, watercourses or surface water, and the vulnerability of people nearby.

Step 3 — Evaluate adequacy of existing controls

Are your current containment measures proportionate to the risk? A 25-litre drum of used engine oil stored on a drip tray with 5 litre capacity is inadequate if the drum can catastrophically fail.

Step 4 — Implement appropriate controls

This is where secondary containment comes in. The Environment Agency's Pollution Prevention Guidance (PPG) and COSHH both point towards bunding as the standard engineering control for liquid chemical storage.

Step 5 — Review and update

COSHH assessments must be reviewed when there is reason to believe the assessment is no longer valid, when there has been a significant change in the work, or at least annually for high-risk substances.

Secondary Containment Rules — The 110% Bund Rule

The requirement for secondary containment in chemical storage is one of the most commonly misunderstood areas of COSHH and Environment Agency compliance. The fundamental principle is straightforward: if a container or system leaks or fails, a secondary containment structure must be able to catch 100% of the substance stored, plus an additional 10% to account for rainfall (for outdoor installations) and the volume of the bund structure itself.

For indoor storage without exposure to rainfall, the 110% rule typically applies to the largest single container. For outdoor storage, you must also account for the volume of rainwater that could accumulate in the bund during a 1-in-10-year rainfall event. Our range of drum spill pallets and IBC bund pallets are sized and certified to meet these requirements.

Specific Storage Requirements Under COSHH

• Segregation of incompatibles: Acids must not be stored adjacent to alkalis; oxidisers must be separated from flammables. Refer to SDS Section 7 for specific incompatibility warnings.
• Labelling: All containers must be clearly labelled in accordance with CLP Regulation — GHS hazard pictograms, signal words (Danger/Warning), and hazard statements must be legible and durable.
• Ventilation: Volatile substances require adequate ventilation — either natural (minimum 1/20th of floor area as openings) or mechanical. COSHH ACoP L5 provides detailed guidance.
• Quantity control: COSHH Regulation 7 requires that quantities of hazardous substances in the workplace are kept to the minimum necessary.
• Access control: Storage areas should be secured against unauthorised access, particularly where substances are toxic or flammable.
• Emergency procedures: Spill kits, absorbents, and first aid materials must be accessible and staff must be trained in their use. Browse our spill kit range for compliant options.

COSHH Documentation Requirements

• COSHH risk assessments (written records required for 5+ employees, strongly recommended for all)
• Safety Data Sheets for every substance — current, accessible to employees
• Exposure monitoring records where WELs apply — retained for 5 years (40 years for carcinogens)
• Health surveillance records where required — retained for 40 years
• Training records — demonstrating employees have received adequate COSHH training
• Containment inspection records — evidence that bunds, drip trays, and storage structures are regularly checked
• Spill and incident records — including near misses, for continuous improvement

Inspections — What HSE Inspectors Look For

• Presence and adequacy of COSHH risk assessments (Regulation 6)
• Suitability and condition of secondary containment — is the bund structurally sound, free from cracks, and of adequate capacity?
• Evidence that bunds are not being used as waste oil sumps (full bunds defeat the purpose)
• Labelling of containers and storage areas
• Availability and condition of spill response equipment
• Staff training — inspectors may question employees directly
• Ventilation arrangements in enclosed storage
• Segregation of incompatible substances

The HSE's publication HSG71 (Chemical Warehousing) and the COSHH Approved Code of Practice (L5) provide the authoritative reference for storage inspections.

Penalties for COSHH Non-Compliance

Beyond prosecution, the HSE can issue Improvement Notices, Prohibition Notices, and Fee for Intervention (FFI) charges — currently £193 per hour for inspector time spent on material breaches.

COSHH Compliance Checklist