Fire Water Tank Size Calculator

Inputs

• Occupancy type — business, assembly, hospital, educational, industrial, warehouse or residential
• Built-up area, which the tool converts to square metres
• Building height band — below 15 m, 15–30 m, above 30 m
• Fire systems in scope — hydrant only, hydrant with wet riser, or hydrant with sprinklers

Method

1. Starts from a base static capacity for the occupancy (from 75,000 L for business, educational and residential to 150,000 L for warehouses), then scales it by a height factor (1 / 1.5 / 2 across the three bands), a system factor (1 for hydrant, 1.15 with wet riser, 1.6 with sprinklers) and an area factor (1 up to 300 m², 1.35 to 1,000 m², 2.2 above).
2. Adds a sprinkler reserve of 20 L per square metre, capped at 120,000 L, when sprinklers are in scope.
3. Rounds the static tank to the nearest 5,000 L with a 50,000 L floor; sets the terrace tank at 10,000, 20,000 or 25,000 L by system and height; selects a 1,620 or 2,280 LPM main pump, a 180 LPM jockey pump and a 60-minute basis.

Assumptions

• The bands are modelled on the NBC 2016 Part 4 pattern for static storage and pump capacities; they are a simplification of the code's tables, not a reproduction of them.
• One building, one tank; a campus with several buildings is sized building by building.
• Municipal make-up water is available to refill the tank — the tool does not size for sites with no replenishment.

Limitations

• State fire-service amendments to NBC, insurer (TAC) requirements and local practice are not modelled and can require more.
• Storage hazard in warehouses — commodity class and rack height — is not an input; high-piled storage can need far more than the warehouse band.
• Special-hazard systems (foam, water mist, deluge) and their own water demand are outside the tool.
• Pump head is not calculated; it depends on building height and the hydraulic design.