To calculate gallons per minute:
Get a container (a bucket, for example) and keep a record of how many seconds it takes to fill the container with water.
Convert the volume of water (bucket's capacity) to gallons.
Divide the volume by the time expressed in seconds to get gallons per second.
Multiply by 60 to get gallons per minute.
This is expressed with the following GPM formula:
GPM = volume / time Read more