Water Pressure Calculator — Is My Pressure Sufficient?
Calculate water pressure from head height or mains supply, including pipe friction losses. Check if your pressure is adequate for showers and taps.
Typical UK: 1.0-4.0 bar. Check with a gauge.
Total pipe length from source to fixture
15mm, 22mm or 28mm
Each elbow adds ~0.6m equivalent length
How We Calculate This
This calculator estimates the effective water pressure at a fixture by starting with the available pressure (from gravity head or mains supply) and subtracting friction losses through the pipe run.
The formulas
Gravity pressure (bar) = Head height (m) × 0.1
Equivalent pipe length = Actual length + (Elbows × 0.6m)
Pressure loss = Equivalent length × Friction factor
Effective pressure = Available pressure - Pressure loss
Fixture minimum pressures
- Basin/bath tap: 0.1 bar
- Kitchen tap: 0.5 bar
- Mixer shower: 0.1 bar
- Thermostatic shower: 0.5 bar
- Power shower: 1.0 bar
- Electric shower: 1.0 bar
- Rain head shower: 1.5 bar
Note: This is a simplified calculation. Real-world pressure depends on many factors including pipe condition, simultaneous demand, and water company supply pressure. For accurate results, use a pressure gauge at the fixture location.
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Verify with your supplier.