heres what you do, take a gallon ziplock bag open it all the way up around the facet open it up full blast for 30secs 5 inches is a gallon in the bag, so if the bag is 1/2 full in 30secs then you have 5-6gallons per min.. this is just for a ruff estimate. i used to use this trick when i worked for Marriott i did engineering quality control and inspections. (basicly i went to properties and made sure they were up to standards in the engineering aspect) i was a chief engineer for 5 yrs prior. anyway it works and its fairly accurate..