Water Tank Size Calculator
Calculate required water storage capacity.
The Water Tank Size Calculator is a free tool designed for construction professionals and enthusiasts. Calculate required water storage capacity. Instantly get the required materials broken down by purchase units, with an option to add a wastage allowance so you never run short on site.
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Result
Result
How to Use This Calculator
- Identify the required flow rate in liters per minute (L/min) or liters per second (L/s).
- Measure the pipe length in meters, including vertical runs.
- Enter the nominal or internal pipe diameter.
- Add estimated minor losses (elbows, valves) if known.
- Click 'Calculate' to get fluid velocity, head loss and recommended diameter.
Frequently Asked Questions
For domestic installations, do not exceed 1.5 m/s in distribution pipes and 2 m/s in collectors. Higher velocities cause noise and erosion.
For a single-family home, the service pipe is usually 25–32 mm, main distribution 20 mm and appliance branches 15–16 mm (½").
Minimum recommended volume is 150–200 litres per occupant for 1-day reserve. For emergency reserves, extend to 2–3 days.