Engineering Calculators

Fire Water Storage Calculator

The fire pump's rated flow — typically forwarded from the Capacity Resolution calculator.

Ordinary Hazard requires 60-90 minutes.

Optional — leave blank to use the conservative maximum automatically.

Leave at 0 for no added margin.

Formula Reference

Required Storage Volume

Vstorage=Qrated×tdurationV_{storage} = Q_{rated} \times t_{duration}

V_storage = required storage volume (gallons), Q_rated = rated fire pump flow (GPM), t_duration = duration used (minutes) — either the selected value within the hazard classification's range, or the conservative maximum if none was selected. A safety margin, if set, is applied on top as (1 + margin/100).

Reference Table

NFPA 13 (2019), Table 11.2.3.1.2 — Water Supply Duration Requirements

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Ordinary and Extra Hazard durations are ranges — NFPA 13 subdivides these classes further (e.g. Ordinary Hazard Group 1/2) in ways this summary table doesn't capture. Hose stream allowance is shown for reference only; it is not added to this calculator's storage volume.