BuildFlo Design Guide · Water · BS EN 806 / IoP
Cold water storage tank calculator
Size cold water storage from IoP daily demand tables or check 24-hour tank level. Free UK cold water storage calculator.
What this calculator does
Cold water storage helps UK building services engineers with iop / custom daily storage sizing, or 24h tank level check. The calculation follows BS EN 806 / IoP methods used in everyday MEP design — enter your project inputs below for a first-pass result.
Whether you searched for "cold water storage", "cold water storage calculator", or "how to cold water storage", this page gives you a working tool plus the context to use it on a real job.
When to use it
Use this for early-stage sizing and sanity checks on UK building services work. It is not a substitute for issued calculations — verify against the project specification, drawings, and relevant standard before sign-off.
How to use it
1. Fill in the inputs for your scenario (defaults are starting points only). 2. Click Calculate — results include the method and assumptions where applicable. 3. Verify against the project specification and relevant standard before issuing.
Typical output unit: litres.
Tips
- Defaults are indicative — replace with project-specific values from the architect, structural, or MEP spec.
- For issued calculations, save results in your BuildFlo project and attach to the calculation folder.
- Need the regulation citation? Open BuildFlo chat in the app and ask about cold water storage under UK standards.
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Frequently asked questions
- How do I size a cold water storage cistern?
- Enter building type and occupancy. Daily demand comes from IoP Table 2, storage percentage from Table 3, giving the required tank volume.
- What is the difference between storage and daily demand?
- Not all daily demand must be stored — Table 3 gives the percentage to hold in the tank to cover peak periods and supply interruptions.
- When do I need a break tank?
- Where mains supply cannot meet peak demand or backflow protection requires air gap separation. Size the break tank on peak diversified flow and refill rate.
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