Take This Quiz to Find out How Skilled Are You With ToolsShare:FacebookPinterestTwitterMailWhat does G.P.M. refer to in plumbing?73%Next Correct Incorrect GPM, or gallons per minute, measures water flow from faucets or shower heads. A lower GPM means more water conservation. What does G.P.M. refer to in plumbing? Gallon Purchase Monitor Growth Period Maximum Gross Pex Measurement Gallons Per Minute 73%