Estimate the total flow a hydrant system must deliver and the water storage that implies, from the flow per hydrant, how many run at once and the duration — an aid to AS 2419.1.
Indicative only. AS 2419.1 sets the number of hydrants to be considered, flow, minimum residual pressure and duration for the specific building — this simplified estimate is not a design.
traqR keeps hydrant systems, block plans and AS 1851 records against each site so testing stays on schedule.
Start free trialEach hydrant has a design flow — AS 2419.1 commonly uses 10 L/s — at a minimum residual pressure at the outlet.
Multiplying the per-hydrant flow by the number assumed to run at once gives the total flow the supply and pump must deliver.
Multiplying the total flow by the required duration gives the water volume the on-site tank or supply must be able to sustain.
AS 2419.1 sets the design flow, the number of hydrants assumed to operate together and the minimum residual pressure for the building. A common figure is 10 L/s per hydrant, with more than one operating for larger buildings. This tool multiplies flow per hydrant by the number running to estimate total demand.
Multiply the total flow by the required duration. At 20 L/s for four hours (14,400 seconds), that’s 288,000 litres, or 288 kL. The actual duration and whether on-site storage is required depend on the building and the town main capacity, as set by AS 2419.1.
Flow alone isn’t enough — the system must also deliver a minimum residual pressure at the hydrant outlet so firefighters get an effective stream. If the available pressure is too low, a fire pump is required. Pressure and pump requirements are covered by AS 2419.1 and AS 2941.
No. It’s an indicative aid. Fire hydrant systems must be hydraulically designed and certified to AS 2419.1 by qualified fire protection designers, with maintenance to AS 1851.
This calculator is an indicative aid, not a substitute for AS 2419.1. The number of hydrants considered, design flow, minimum residual pressure, duration and storage must be determined by qualified fire protection designers for the specific building, with maintenance to AS 1851.
traqR keeps hydrant systems, block plans and AS 1851 records against each site. Try it free for 14 days.