HACCP Principles

Constructing & Verifying Your Flow Diagram

How to Create and Verify a Process Flow Diagram for HACCP

Quick answer

A flow diagram is a visual map of every step in your food operation, from receiving raw materials through to serving the finished product. It is the third preliminary step of the Codex HACCP methodology and provides the foundation for your hazard analysis. Without an accurate flow diagram, you risk missing process steps where hazards could be introduced or increase. This article explains how to construct a flow diagram for a hospitality operation and, crucially, how to verify it by walking the actual process on your premises.

The flow diagram must cover every step from receiving to service, including decision points and rework loops.
Always verify the diagram by walking the actual process during normal operations.
A physical flow diagram overlaid on your kitchen floor plan helps identify cross-contamination risks.

Key takeaways

The flow diagram must cover every step from receiving to service, including decision points and rework loops.

Always verify the diagram by walking the actual process during normal operations.

A physical flow diagram overlaid on your kitchen floor plan helps identify cross-contamination risks.

Update and re-verify the flow diagram whenever processes, layout, or equipment change.

What Your Flow Diagram Should Cover

Your flow diagram should include every step where food is handled, processed, stored, or moved. For a typical restaurant, this includes: receiving deliveries, checking and accepting goods, dry storage, cold storage (fridge and freezer), preparation (washing, chopping, portioning), thawing (if applicable), cooking, cooling, reheating, hot holding, cold holding, plating and service, and waste disposal. Include decision points where the food might follow different paths. For example, after preparation, some items go directly to cooking while others go to cold storage for later use. Show these branches clearly. Also include any rework loops - food that is cooled and reheated, for instance, goes through the danger zone twice and this must be visible in the diagram. The diagram does not need to be artistically beautiful. A clear, legible chart that anyone on your team can follow is sufficient. Use standard flow chart symbols if you wish (rectangles for process steps, diamonds for decisions), but clarity matters more than convention.

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Building the Diagram Step by Step

Start at the very beginning: the moment ingredients arrive at your premises. Walk the entire process mentally (or better, physically) and list every step in sequence. Receiving: goods arrive, temperature checks are performed, packaging is inspected, items are date-labelled. Storage: items are placed in appropriate storage (dry store, fridge, freezer) within defined timeframes. Preparation: items are removed from storage, washed or prepped, portioned. Note where cross-contamination between raw and ready-to-eat could occur. Cooking: note all cooking methods used (grilling, frying, baking, boiling, sous vide). Each may have different critical limits. Post-cooking: does food go directly to service, to hot holding, to cooling for later use, or to blast chilling? Map each pathway. Service: how is food held before it reaches the customer? Is it plated immediately, held in a pass, or held in a hot cabinet? Finally, map food return and waste: what happens to uneaten food, plate waste, and food returned by customers?

Verifying the Flow Diagram On-Site

The Codex guidelines require that the flow diagram is verified by walking the actual process on-site. This step is critical and frequently neglected. What you think happens in your kitchen and what actually happens are often different. Walk through the operation during a busy service and during a quiet period. Check that every step on your diagram actually occurs as documented. Look for steps you missed: does food sit on a counter between preparation and cooking? Is there an intermediate storage step you did not account for? Do staff take shortcuts during busy periods that bypass documented steps? During verification, also check the physical layout. Is the flow from raw to cooked logical, or do paths cross in ways that create contamination risks? Are storage areas used as documented, or has the dry store become an overflow for cleaning chemicals? Annotate your diagram with any corrections discovered during verification. The verified, corrected version becomes the official diagram for your HACCP plan. Re-verify whenever you change your kitchen layout, equipment, or processes.

Common Flow Diagram Formats for Hospitality

There are several approaches that work well. A linear flow chart works for simple operations: receiving flows to storage flows to preparation flows to cooking flows to service. For more complex operations, a branching flow chart shows where products take different paths. Some businesses use a combined process map that shows multiple product types side by side - cooked meat, raw vegetables, and ready-to-eat items each following their own pathway through the kitchen, with cross-over points clearly marked. Another useful format is the physical flow diagram, which overlays the process steps on a floor plan of your kitchen. This immediately highlights where clean and dirty processes intersect, where raw and ready-to-eat foods might cross paths, and where the physical layout supports or undermines your food safety controls. Many EHOs find the physical flow diagram particularly helpful as it connects the process to the actual premises they are inspecting.

What to do next

Walk your operation and list every step

Starting from the delivery door, follow the path of food through your premises and record every step. Do this during a busy service to capture what actually happens.

Draw your flow diagram

Convert your step list into a clear flow chart. Include branches where products take different paths and mark any points where raw and ready-to-eat foods could cross-contaminate.

Verify the diagram with your team

Show the flow diagram to staff who work at each stage and ask whether it accurately represents what they do. Correct any discrepancies.

Common mistakes to avoid

Mistake

Drawing the flow diagram from memory without on-site verification

Instead

Always verify by walking the process. What you think happens and what actually happens during a busy service are often different.

Mistake

Missing intermediate steps like thawing or interim storage

Instead

These "gap" steps are often where temperature abuse occurs. Account for every moment food is out of controlled storage.

Frequently asked questions

How detailed should my flow diagram be?

Detailed enough that someone unfamiliar with your kitchen could understand the process. Every step where a hazard could be introduced, increase, or be controlled should be visible. However, you do not need to document every knife cut or stir. Focus on steps that affect food safety.

Do I need a separate flow diagram for every dish?

No. Create flow diagrams for product categories that follow the same process. You might have one diagram for cooked-to-order items, one for batch-cooked and cooled items, and one for cold ready-to-eat items. Only create separate diagrams where the process is fundamentally different.

Should I include cleaning steps in the flow diagram?

Cleaning between tasks (e.g. sanitising a surface after preparing raw chicken before preparing salad) should be shown if it is a critical control related to cross-contamination. General end-of-day cleaning is typically covered by your cleaning schedule as a prerequisite programme rather than on the flow diagram.

HACCP Principles