Fire Suppression
Water Supply Demand
Total GPM and pressure required from the water supply for a sprinkler system. For fire pump sizing and supply availability checks.
⚠ For preliminary planning
Real demand depends on the hydraulically most-demanding sprinklers + the actual riser layout. A hydrant flow test against your supply curve is required to confirm.
FAQ
What's a hydrant flow test? +
A test where the fire department flows a hydrant near your building and measures static + residual pressure. Plotted on log-log paper, this gives your "water supply curve" — the GPM/PSI available at the connection.
When do I need a fire pump? +
When your system demand point (this calc's output) is above the available supply curve at the same flow. Common for high-rise, big-box retail, and sites with weak municipal supplies.
What about gravity tanks? +
Elevation × 0.433 = static pressure available from a tank. A tank 100 ft above the system gives 43.3 psi static. Used where municipal water is unreliable or absent.