Water Flow Rates (GPH)
Pipe Size (ID) Gravity Drain Pressure Return
1/2 Inch 200 1,260
3/4 Inch 400 2,160
1 Inch 600 3,510
1.25 Inch 1000 5,940
1.5 Inch 1400 7,560
2 Inch 2200 12,000
2.5 Inch 3200 17,550

 

These are estimates. Your mileage may vary.