How To Conduct A Chemical Storage Risk Assessment (COSHH)

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Storing chemicals is often treated as an afterthought, yet many serious incidents start in the store, not at the bench. Incompatible products, unnoticed vapours and creeping quantities create fire, explosion and health risks. UK law expects more: under COSHH and DSEAR you must assess storage as rigorously as use.

The fix is a structured storage risk assessment that ties together your inventory, compatibility, environment and emergency planning. With up‑to‑date SDSs, a simple risk matrix and clear segregation rules, you can prioritise controls that prevent harm to people, property and the environment—and stay compliant.

This practical guide takes you step by step through defining scope and legal duties (COSHH, DSEAR, CLP), building a complete inventory, mapping stores and waste points, identifying who could be harmed, analysing hazards, checking compatibility and segregation, assessing cabinets, ventilation, bunding and ignition control, setting quantity limits and access, choosing controls via the hierarchy, planning for spills and fire, and documenting, monitoring and reviewing. You’ll get templates, examples and HSE‑aligned tools to produce an auditable, action‑ready assessment.

Step 1. Define scope, responsibilities and legal duties (COSHH, DSEAR, CLP)

Begin by fixing the scope and ownership of your chemical storage risk assessment. Include every storage location (cupboards, flammable cabinets, external stores, fridges/freezers, cold rooms), movements to and from stores, decanting, and waste holding. Name a competent assessor, a store owner, and a senior manager who signs off and funds actions.

  • Scope: All stores, transfers, decanting and waste; normal and abnormal conditions (spills, maintenance, out‑of‑hours).
  • Roles: Employer (duty holder), responsible manager, competent assessor (COSHH/DSEAR), storekeepers (daily checks), facilities/LEV/fire safety.
  • Legal duties: COSHH—assess storage as well as use, control exposure, train and maintain; DSEAR—assess fire/explosion risks, zoning, ignition control and ventilation; CLP—classification, labelling and SDSs to drive segregation, signage; record and review.

Step 2. Build a complete chemical inventory and collect current SDSs

Start with a complete inventory. Walk the site and reconcile against purchasing and waste records. Include chemicals brought in, those generated by activities, and wastes awaiting disposal. For each item capture identity, CLP hazards, quantity, container/size, precise location and storage conditions, and obtain a current supplier Safety Data Sheet (SDS).

  • Confirm latest SDS: check the revision date; use Sections 2 (hazards), 7 (storage), 8 (controls) and 10 (reactivity).
  • Flag specials: date peroxide‑formers (receipt/opening/disposal); keep highly toxic/shock‑sensitive/habit‑forming chemicals locked; ensure ventilation for fuming/highly volatile substances.

Step 3. Map storage locations, product flows and waste accumulation points

Turn your inventory into a map. On a scaled plan mark every storage point (cabinets, rooms, cages, fridges/freezers and outdoor stores), delivery and internal transfer routes, decanting/dispensing spots and waste holding areas. Record protections and vulnerabilities: segregation, bunds/sills and drainage to sumps, ventilation/LEV and exhaust points, ignition sources, doors/exits, lifts/ramps, proximity to occupied areas and any potential DSEAR zones.

Step 4. Identify who could be harmed and how in storage operations

Pin down every person who may be exposed during storage tasks and abnormal events (deliveries, put‑away, stock checks, decanting, spill clean‑up, maintenance, out‑of‑hours). For each group note where they are, what they do, how often, and the likely exposure routes: inhalation, skin/eye contact, ingestion or injection.

  • Store and lab staff: vapours, splashes, manual‑handling spills during receipt/decanting.
  • Cleaners/maintenance/contractors: disturbance of residues, unlabelled wastes, ignition sources.
  • Nearby workers/visitors/delivery drivers: bystander exposure from leaks or vented cabinets.
  • Waste handlers: mixed incompatibles, fuming/volatile wastes during transfer.
  • Out‑of‑hours responders/emergency services: acute toxic exposure, fire/explosion overpressure (DSEAR).
  • Vulnerable groups: young workers, pregnant/nursing, those sensitised or reprotoxin‑at risk.

Step 5. Analyse storage-specific hazards (fire, explosion, toxicity, reactivity and environment)

In your chemical storage risk assessment, evaluate hazards for each substance at each location using CLP classification and the SDS (Sections 2, 7 and 10) alongside real conditions: quantities, container integrity, temperature/volatility, ventilation and nearby ignition sources. Container size/fragility and long‑term storage (e.g., peroxide‑formers) can escalate risk.

  • Fire: Low flash‑point liquids; vapours plus ignition sources.
  • Explosion: Spills/leaks forming explosive atmospheres in confined areas (DSEAR).
  • Toxicity: Acute/chronic hazards; fuming/volatile chemicals without ventilation.
  • Reactivity: Oxidisers/reducers, water‑reactives, peroxide‑formers; shock‑sensitive.
  • Environment: Aquatic toxicity; no bunding; drains/watercourses at risk.

Step 6. Check compatibility and plan segregation by hazard class

In your chemical storage risk assessment, use CLP classes and SDS Sections 7 and 10 to group chemicals and set segregation rules. Don’t store alphabetically. Apply separation (distance), segregation (barrier) or isolation (dedicated cabinet/room) so one breakage can’t mix incompatibles or build reactive vapours. Lock highly toxic/shock‑sensitive substances and ventilate for fuming/volatile chemicals. Flammable‑liquid cabinets must be dedicated.

  • Flammables: Dedicated cabinets; keep away from oxidisers.
  • Oxidisers: Segregate from flammables, organics and reducers.
  • Acids/bases/bleach: Store apart; never with hypochlorites.
  • Peroxide‑formers: Store separately; date receipt/opening/disposal.

Step 7. Assess the storage environment (ventilation, cabinets, bunding and ignition control)

In your chemical storage risk assessment, assess the room and hardware, not just the bottles. Confirm ventilation, cabinet design, spill containment and ignition control match your hazards. Storage rooms should disperse vapours effectively (≈5 air changes/hour) with extraction to a safe external point (≥3 m from openings). Flammable‑liquid cabinets need 30‑minute fire resistance and bunding to ≥110% of the largest container. Eliminate ignition sources, apply DSEAR zoning where explosive atmospheres could arise, and use ventilated cabinets for fuming/volatile chemicals.

Step 8. Set quantity limits, working stock rules and access controls

Set quantity caps and access rules. In flammable‑liquid cabinets keep ≤50 L of highly flammables (with flashpoint < ambient) and ≤250 L for others up to 55°C; above needs risk assessment. Keep minimal stock at bench (workshops: ≤1 L on open benches). Restrict access to authorised personnel; lock cabinets/rooms for highly toxic, shock‑sensitive or habit‑forming chemicals. Treat empties as flammable; keep closed in flammable store.

Step 9. Evaluate risk with a simple matrix and prioritise actions

Use a simple 5×5 matrix to score each substance at each storage point. Rate Severity and Likelihood from 1–5 using CLP/SDS data and real conditions, then calculate Risk = Severity × Likelihood. Band results: 1–5 low, 6–10 medium, >10 high. Rank the list and target the highest first in your chemical storage risk assessment.

  • Score severity: fire/explosion potential, acute/chronic toxicity, environmental harm.
  • Score likelihood: quantity, volatility/temperature, container integrity, ventilation, ignition sources, handling frequency.
  • Prioritise actions: High = immediate controls; Medium = planned controls; Low = monitor.
  • Assign accountability: name an owner and due date; flag DSEAR‑related highs for zoning/ignition control review.

Step 10. Select controls using the hierarchy (eliminate, substitute, engineering, admin, PPE)

In your chemical storage risk assessment, apply the hierarchy to each high/medium risk and note the justification from SDS Sections 7, 8 and 10. Remove or replace hazards before turning to equipment, procedures or PPE.

  • Eliminate: purge obsolete stock; just‑in‑time deliveries; smallest pack sizes; remove bench stock.
  • Substitute: water‑based products; higher flash‑point solvents; pellets not powders.
  • Engineering: 30‑minute flammable cabinets; bunds ≥110%; ventilated storage/extraction ≥3 m from openings; segregation; locked toxics.
  • Administrative: segregation SOPs, FIFO, weekly checks; date peroxide‑formers (receipt/open/disposal); clear labelling/signage; maintenance permits.
  • PPE: last line—specify gloves/RPE from SDS Section 8; provide spill kits and eyewash.

Step 11. Plan for emergencies, spills and fire (equipment, procedures and drills)

When storage fails, seconds matter. Turn your COSHH/DSEAR findings into practical emergency plans for spills, leaks and fire, including incidents nearby that could impact the store.

  • Emergency equipment: spill kits matched to hazards (HF‑compatible), eyewash/showers, drain covers, and fire‑fighting kit.
  • Containment/drainage: bunds ≥110% largest container, 150 mm sills, sloped floors to sump/interceptor; drain sealing.
  • Procedures/drills: alarm/evacuation, ignition control (DSEAR), PPE per SDS; make SDSs available to responders; drill and maintain.

Step 12. Document your COSHH/DSEAR assessment and action plan

Produce an auditable pack: scope, inventory with CLP hazards and current SDSs; risk register by location with matrix scores and residual risk; compatibility/segregation plan and any DSEAR zoning sketches; defined control standards (cabinet fire rating, bund capacity, ventilation); emergency procedures; and an action plan with owners, due dates, version control and a scheduled review.

Step 13. Implement inspections, maintenance and monitoring

In your chemical storage risk assessment, turn controls into routines: use checklists to verify cabinet condition and rating, bund capacity (≥110% largest container), effective ventilation, segregation and labelling, dated peroxide‑formers, locked storage for toxics, spill kit suitability and housekeeping. Record inspections, log defects, fix promptly, and track actions and near‑misses.

Step 14. Establish review triggers and reassessment frequency

Lock in when you’ll revisit the chemical storage risk assessment. Set a maximum review interval of 12 months, and trigger a reassessment on change: new substances or revised SDSs; quantity/location/equipment changes; incidents or near‑misses; inspection failures; staffing or shift changes (including pregnancy); legal/standards updates; or DSEAR zoning/ventilation alterations.

Step 15. Special cases: fridges/freezers, outdoor stores, gas cylinders and waste

Some storage contexts need tighter, explicit controls. Miss them and you risk hidden ignition sources, uncontrolled spills to drains, cylinder explosions and waste reactions. Bake these rules into your chemical storage risk assessment and your day-to-day checks.

  • Fridges/freezers: Never use domestic units for flammables. Use internally “spark‑free” or explosion‑proof equipment; label non‑approved units. No food. Cold rooms require explosion‑proof wiring for flammables.
  • Outdoor stores: Provide a 150 mm sill or bund sized to ≥110% of the largest container; slope surfaces to a sump/interceptor; remove combustibles within 1 m; use compatible absorbents.
  • Gas cylinders: Secure upright, ventilate and control ignition sources. Plan for acetylene cooling (up to 24 h) after fire; consider drainage and DSEAR zoning.
  • Waste: Treat as products or worse—segregate incompatibles, ventilate for fuming/volatile wastes, date/label, keep containers closed. Store “empties” with residual vapour in the flammable store until cleaned and aired.

Step 16. Common pitfalls to avoid in chemical storage

Most storage incidents stem from predictable mistakes. Avoid the traps below and your chemical storage risk assessment will stand up to COSHH/DSEAR scrutiny while protecting people, property and the environment.

  • Alphabetical storage: mixes incompatibles.
  • Domestic fridges for flammables: internal ignition sources.
  • No segregation: oxidisers with flammables; acids with hypochlorites.
  • Overfilled cabinets/bunding: exceed limits; bund <110%.
  • Poor ventilation/ignition control: vapours plus sparks/hot surfaces.
  • Peroxide‑formers not dated: shock‑sensitive over time.
  • Unlabelled decants: loss of CLP/SDS information.
  • Storing in fume cupboards: impairs containment and promotes mixing.

Step 17. Templates and tools to speed up your assessment

Speed comes from structure. Standardise your storage assessment with reusable templates aligned to COSHH/DSEAR/CLP.

  • Inventory & SDS register: name, CLP hazards, quantity, location, SDS date.
  • Storage map & zoning sketch: cabinets, ventilation, ignition sources, bunds.
  • Compatibility/segregation matrix: CLP groups; separation, segregation, isolation rules.
  • 5×5 risk + action log: scores, owner, due date, status.

Step 18. When to involve a DGSA or specialist support

Bring in a DGSA or specialist when your chemical storage risk assessment touches dangerous goods transport, complex DSEAR issues, or engineering controls you can’t specify with confidence. Typical triggers include zoning and ignition source control, ventilated or explosion‑relief stores, spark‑free refrigeration, drainage/interceptors, large flammable stocks, highly toxic/shock‑sensitive materials, or recurring near‑misses and inspection failures.

Step 19. Prepare people: training, briefings and competence records

Controls only work when people are competent. Convert your chemical storage risk assessment into targeted training, toolbox briefings and clear authorisations. Base content on SDSs and SOPs, cover DSEAR ignition control and emergency roles, and refresh at least annually and whenever anything changes.

  • Induction + job‑specific: receiving/decanting, segregation rules, cabinet use, labelling.
  • Spill/fire response: alarms, evacuation, spill kits, eyewash/showers.
  • PPE & hygiene: selection, limitations, don/doff, hand‑washing and no‑food rules.
  • Change briefings: updates when SDSs/processes change; signage.
  • Competence records: attendance, short assessments, authorised‑person lists, drill logs.

Key takeaways and next steps

A robust chemical storage risk assessment turns stores from a blind spot into a controlled asset. Tie together your inventory, compatibility rules, storage environment and emergency readiness, and use SDSs plus COSHH/DSEAR duties to drive pragmatic controls and auditable decisions.

  • Define scope: roles and legal duties.
  • Keep a live inventory: with current SDSs.
  • Segregate by hazard class: never alphabetically.
  • Engineer the store: ventilation, fire‑rated cabinets, bunding, ignition control.
  • Set limits and competence: stock caps, locked high hazards, train, document and review.

For templates, coaching or DGSA support, contact Logicom Hub.