Water: Maximum flow through Flexible PVC Pipe April 22, 2026 22:56 Updated Approximate Maximum Flow Through Flex Pipe1.5" Flex Pipe: 2,200 GPH (gallons per hour) ≈ 8,327 liters per hour (LPH)2" Flex Pipe: 4,800 GPH ≈ 18,170 liters per hour (LPH)3" Flex Pipe: 11,500 GPH ≈ 43,532 liters per hour (LPH) Related articles Water: Volume in a Stream What size tubing should I use (1", 1.25", 1.5")? What is the best way to hide the face of the Waterfall Spillway? Stone: Quantity of Boulders for a Waterfall Spillway Waterfall: What flow rate is needed for a waterfall?