NFPA 25 work procedure

Water Supply Analysis Workflow

Use hydrant test readings to estimate available flow, compare demand, and document preliminary water supply margins.

Page role

Use this page for a defined task before moving to the next project record.

Audience: Engineers, designers, contractors, technicians, and reviewers following a tool-backed workflow.
Job: Use hydrant test readings to estimate available flow, compare demand, and document preliminary water supply margins.
Evidence: Hydrant test date, location, static pressure, residual pressure, outlet diameter, and pitot reading.; Measured flow, available flow at required residual, and supply curve point record.; System demand or pump demand used for comparison against available water supply.
Output: Static, residual, pitot, outlet, and flow data belong to the same test event.; Available flow is calculated at the required residual pressure used for demand comparison.; Demand and supply comparison uses compatible GPM and pressure basis.
Next: Start with the related worksheet, run the linked calculators, then retain reviewed values before project use.

1Open the worksheet first when the guide spans multiple calculations or review gates.
2Use each linked calculator only after the input source for that step is known.
3Keep warning states, assumptions, and review notes with the project record.
4Move to the handoff panel after the guide sequence is complete.

Follow the sequence as an engineering workflow: each phase lists the action, tools, and evidence to retain before moving forward.

Phase	Action	Tools	Evidence to keep
Step 1	Record static and residual pressures.	Hydrant Flow Test Calculator	Document the source used to start the NFPA 25 workflow.
Step 2	Calculate flow from pitot pressure and outlet diameter.	Hydrant Flow Test Calculator, Available Water Supply Calculator	Keep calculation notes showing how this step supports: calculate flow from pitot pressure and outlet diameter.
Step 3	Estimate available flow at the required residual pressure.	Hydrant Flow Test Calculator, Available Water Supply Calculator	Keep calculation notes showing how this step supports: estimate available flow at the required residual pressure.
Step 4	Compare available flow to system demand.	Hydrant Flow Test Calculator, Available Water Supply Calculator	Keep calculation notes showing how this step supports: compare available flow to system demand.
Step 5	Flag low-margin conditions for engineering review.	Hydrant Flow Test Calculator, Available Water Supply Calculator	Record the reviewed output, warning state, and next review decision.

1Hydrant test date, location, static pressure, residual pressure, outlet diameter, and pitot reading.
2Measured flow, available flow at required residual, and supply curve point record.
3System demand or pump demand used for comparison against available water supply.
4Low-margin, stale-test, mixed-test, or AHJ/utility follow-up notes.

1Static, residual, pitot, outlet, and flow data belong to the same test event.
2Available flow is calculated at the required residual pressure used for demand comparison.
3Demand and supply comparison uses compatible GPM and pressure basis.
4Stale, incomplete, or low-margin water supply data is flagged before pump or sprinkler reliance.

1Open the hydrant flow and water supply worksheet before comparing supply against demand.
2Use the pitot, available-flow, and supply-curve calculators only with same-test data.
3Carry the required residual pressure basis into sprinkler demand or pump worksheets.
4Route questionable test data to AHJ, utility, or project engineering review before reliance.

Water Supply Analysis Workflow

1Open the hydrant flow and water supply worksheet before comparing supply against demand.
2Use the pitot, available-flow, and supply-curve calculators only with same-test data.
3Carry the required residual pressure basis into sprinkler demand or pump worksheets.
4Route questionable test data to AHJ, utility, or project engineering review before reliance.