Fire Water Tank Calculator

NFPA requires every building above 15m height or with specified occupancy to have a dedicated fire water reserve sufficient for combined hydrant and sprinkler operation. This tank must be exclusive to fire fighting use - domestic water supply must not reduce the fire reserve. The fire water tank is separate from the domestic water storage and must be accessible to the fire brigade.

NFPA and TAC (Tariff Advisory Committee) guidelines govern fire water storage for insurance compliance. Most insurance companies in the US require TAC-compliant fire protection systems for coverage. The fire water tank inlet must be fitted with a ballcock valve that shuts off at high level. A dedicated fire water pump with auto-start on pressure drop, jockey pump for pressure maintenance, and a diesel standby pump (for power failure) is mandatory for buildings requiring NFPA compliance.

Example: A 20-storey residential tower (height greater than 60 m) requires a hydrant flow of 2280 L/min for 60 minutes per NFPA: V_hydrant = 2280 × 60 = 136,800 L (136.8 KL). The building also has an Ordinary Hazard 1 sprinkler system: V_sprinkler = 900 L/min × 60 min = 54,000 L (54 KL). Total fire water reserve = 136.8 + 54 = 190.8 KL, stored in a dedicated underground fire tank separate from the domestic supply, sized after the fire consultant applies standard safety margins.