Free tool
Water Tank Size Calculator
Enter apartments or people; see the recommended modular water tank volume with daily consumption, reserve days and fire reserve — rounded to the nearest standard modular size (1.08 m panels).
Once sized, see the modular water tank page for technical details, or design it in 3D.
An average of 4 people per apartment is assumed.
How many days of water reserve?
Fire reserve (optional)
Recommended tank volume
58 m³
≈ 28.8 m³ daily consumption
Suitable standard size: 9.2 × 5.9 × 1.1 m = 58.9 m³nearest modular size (1.08 m panels), rounded up
FAQ
How many m³ of water storage does a building need?
A common assumption is 150 litres per person per day. A 48-apartment site (≈192 people) needs about 29 m³ per day; with a 2-day reserve, a tank of 58 m³ or more is recommended.
How much fire reserve should be added?
Fire reserve is set by the project's fire report; 10, 36 or 72 m³ are common scenarios. It is added on top of the domestic volume.
How are modular tank dimensions chosen?
Bolted modular steel tanks are built from 1.08 m panels; length, width and height adjust in half-module steps. Pick the nearest standard size above the calculated volume.