Studio Matrx Monthly · Volume 1 · Issue 2 · July 2026
Amogh N P
 In loving memory of Amogh N P — Architect · Designer · Visionary 
Fire water storage

Fire Tank Size Calculator

The usable water in a fire tank must equal your required fire reserve. The built tank is bigger — it also carries freeboard and the water below the pump suction that can never be drawn. Enter the reserve, an allowance and a usable depth to get the gross volume and a footprint check. An indicative planning estimate, NOT a fire design. Runs in your browser.

0.0
Gross tank volume to build
0 KL
Gross capacity
0 KL
Usable reserve
Suggested square footprint (check only)
0.0 × 0.0 m
plan area 56.0 m² at 3 m usable depth
How the gross volume splits
  • Usable fire reserve150 KL
  • Freeboard + dead water (12%)18 KL

The fire reserve is DEDICATED. Arrange any low-level domestic draw-off ABOVE the fire-reserve level so everyday use can never deplete it. NBC (SP 7:2026) often splits storage between an underground static tank and a terrace tank, and a real tank is rarely a perfect square — this footprint is only a sizing check.

Life-safety notice. This is an indicative planning estimate, NOT a compliant fire design or a statutory calculation, and it is not a Fire-NOC-ready or code-compliant number. The real requirement depends on your occupancy classification, building height and the AHJ, and the actual allowance for dead water depends on the exact pump-suction and level-control detail. A LICENSED FIRE CONSULTANT must design the tank, suction and level controls, and the LOCAL FIRE OFFICER / AHJ must sign them off. A wrong number here can cost lives — verify everything against NBC Part 4 (SP 7:2026) and the relevant IS codes for your occupancy.