Fire Water Storage Calculator

Fire water tank capacity from sprinkler demand and fire flow.

Sprinkler demand (GPM)

Hazard classification

Standpipe demand (GPM)

Additional hose stream (GPM)

Manual duration override (min)

Domestic reserve (gal)

Tab to move between fields

Fire water storage (gal)

30,000

Total tank capacity (gal)

30,000

Total system flow (GPM)500

Supply duration (min)60

Hose stream allowance (GPM)250

Storage volume (cu ft)4,011

Storage volume (liters)113,550

Est. tank diameter (ft)17.2

Est. tank height (ft)17.2

Suction pipe size (in)6

How to Use This Calculator

Enter Sprinkler demand (GPM), Hazard classification, and Standpipe demand (GPM).
Set Additional hose stream (GPM), Manual duration override (min), and Domestic reserve (gal).
Review Fire water storage (gal) and Total tank capacity (gal).
Use Total system flow (GPM) and Supply duration (min) to inform your decision.

How the result changes with Sprinkler demand (GPM)

Sprinkler demand (GPM): Sprinkler system hydraulic demand from calculations.
Hazard classification: 1=Light, 2=Ordinary G1, 3=Ordinary G2, 4=Extra G1, 5=Extra G2. Sets duration and hose stream.
Standpipe demand (GPM): Standpipe system demand if combined water supply (0 if not applicable).
Additional hose stream (GPM): Additional hose stream demand beyond NFPA 13 minimum.
Manual duration override (min): Override NFPA default duration. 0 = use NFPA standard for hazard class.
Domestic reserve (gal): Domestic water reserve if using a combined fire/domestic tank.

Fire water storage (gal): Required fire protection water storage volume.
Total tank capacity (gal): Fire water plus domestic reserve.
Total system flow (GPM): Combined sprinkler + hose stream + standpipe flow.
Supply duration (min): Water supply duration per NFPA 13 or manual override.
Hose stream allowance (GPM): Total hose stream flow per NFPA 13 plus any additions.
Storage volume (cu ft): Tank volume in cubic feet.
Storage volume (liters): Tank volume in liters.
Est. tank diameter (ft): Estimated cylindrical tank diameter (1:1 height-to-diameter ratio).
Est. tank height (ft): Estimated tank height.
Suction pipe size (in): Minimum suction pipe diameter to keep velocity ≤10 ft/s.

Identify Input Parameters
4 parameters
Sprinkler demand (GPM) = 250, Hazard classification = 2, Standpipe demand (GPM) = 0, Additional hose stream (GPM) = 0 = 6 input(s) provided
Calculate Fire water storage
Fire water storage = totalFlowGPM * effectiveDuration
30000 = 30000
Calculate Total tank capacity
Total tank capacity = fireWaterGallons + domesticReserveGal
30000 = 30000
Calculate Total system flow
Total system flow = sprinklerDemandGPM + totalHoseStream + standpipeDemandGPM
500 = 500
Calculate Supply duration
60 = 60