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Correctly sized pipes deliver adequate pressure. Undersized pipes create pressure drops; oversized pipes waste money. Here is the calculation.
The Formula
Q = A × v | A = π(d÷2)² | Recommended velocity: 1-3 m/s supply, 0.5-1.5 m/s drainage
Standard formula used by professionals worldwide
Worked Example
Step-by-step
Hot water branch: need 0.1 L/s at 2m/s → A = 0.00005m² → diameter minimum 8mm
Key Concepts
- Accuracy: Results are as accurate as the inputs you provide
- Units: Always use consistent units throughout your calculation
- Verification: Double-check important calculations before making decisions
- Professional advice: For major financial, health, or structural decisions, consult a qualified professional
Privacy and Security
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- No data is sent to any server
- No sign-up or personal information required
- Your data stays private — always
Frequently Asked Questions
Causes of low water pressure?
Undersized pipes, partial blockage, scale buildup, or insufficient main supply pressure.
Typical domestic pipe sizes?
15mm branches to fixtures. 22mm main supply lines. 32-50mm rising mains.
Water tower pressure?
Each 10m height = 1 bar (14.5 PSI). Simple and reliable pressurisation.