Flow rate measures the amount of water exiting your faucet per minute (GPM), while water pressure, measured in Pounds per Square Inch (PSI), is the force that moves water through your pipes. High pressure doesn’t equate to high flow, as obstructions, leaks, and the usage of multiple fixtures can reduce flow at certain points. Since 1992, the EPA has mandated a maximum flow rate of 2.5 GPM for new showerheads to promote water conservation. For detailed regulations, visit the EPA’s website:https://www.epa.gov/watersense.