## Things You Will Need

- Calculator with pi function
- Velocity-type water meter

Water flow is a calculation used for builders when determining the overall fixtures and plumbing for a building. If the building is in an area with lower water flow from the municipal pipes, then use this equation for determining the necessary pipe size for optimal water pressure.

- Multiply pi by 0.25.
- Press the multiply button again and enter the pipe diameter squared.
- Press the multiply button again and enter the velocity of the entering water. The velocity of water is obtained by attaching a velocity-type water meter to the pipe and running the water. Lengths of time necessary for a velocity reading vary depending upon the manufacturer, so review your meter's user manual for testing requirements.
- Press enter. The answer is your water's flow rate.

## Things You Will Need

- Calculator with pi function
- Velocity-type water meter