PEXSUPPLY RESOURCES GPM Chart for Copper & PEX Pipe Tubing Size/Type Minimum Flow Rate1 (gpm) 3/8" Copper 1/2" Copper 3/4" Copper 1" Copper 1.25" Copper 1.5" Copper 2" Copper 2.5" Copper 3" Copper 1.0 1.6 3.2 5.5 8.2 11.4 19.8 30.5 43.6 3/8" PEX 1/2" PEX 5/8" PEX 3/...