Water Supply Pipe Sizing Calculator
Static · formula-only · worked example computed when this page was built · no live data
The Water Supply Pipe Sizing Calculator turns the water fixture units (WFU) into a peak flow, sizes the pipe on velocity, then checks the pressure left at the far fixture. Example: for a flush-valve supply serving 10 WCs and 8 lavatories over 40 m, on a 350 kPa supply, Total WFU = 108, Peak flow = 76.1 L/min, Recommended diameter = 32 mm, Velocity = 1.58 m/s, Residual pressure = 311.5 kPa, Minimum residual = 70 kPa (per Philippine Plumbing Code Table A-2/A-3).
How it works
Computed from your inputs per Philippine Plumbing Code Table A-2/A-3. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (Plumbing & Pumps)
Inputs: a flush-valve supply serving 10 WCs and 8 lavatories over 40 m, on a 350 kPa supply.
| Result | Value |
|---|---|
| Total WFU | 108 |
| Peak flow | 76.1 L/min |
| Recommended diameter | 32 mm |
| Velocity | 1.58 m/s |
| Residual pressure | 311.5 kPa |
| Minimum residual | 70 kPa |
Computed by WorkHive's calculation engine when this page was built; standard: Philippine Plumbing Code Table A-2/A-3.
How to use this calculator
- Read the worked example. It uses a flush-valve supply serving 10 WCs and 8 lavatories over 40 m, on a 350 kPa supply and shows every number in the method.
- Follow the formula with your own figures: it returns Total WFU, Peak flow, Recommended diameter, Velocity, Residual pressure, Minimum residual, computed per Philippine Plumbing Code Table A-2/A-3.
- To compute interactively, open the Water Supply Pipe Sizing Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a water supply pipe sizing calculator WFU?
The Water Supply Pipe Sizing Calculator is a free online tool that turns the water fixture units (WFU) into a peak flow, sizes the pipe on velocity, then checks the pressure left at the far fixture. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following Philippine Plumbing Code Table A-2/A-3. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive Water Supply Pipe Sizing Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.