Resources, Tools and Basic Information for Engineering and Design of Technical Applications!
mobile - visible on handheld devices - alternatively go to www.engineeringtoolbox.com!
Engineering ToolBox > Capacity of Sewer Pipes
The diagrams below can be used for design of sewage and wastewater gravity conveying systems where capacities in GPM or liter per second and the slopes of the pipe lines are known.


The table below indicates sewage pipe capacity in gpm:
| Carrying Capacity of Sewer Pipe (gallons per minute) | ||||||||
| Size of pipe (inches) | Decline per 100 ft pipe (feet) | |||||||
| 1 | 2 | 3 | 6 | 9 | 12 | 24 | 36 | |
| 3 | 13 | 19 | 23 | 32 | 40 | 46 | 64 | 79 |
| 4 | 27 | 38 | 47 | 66 | 81 | 93 | 131 | 163 |
| 6 | 75 | 105 | 129 | 183 | 224 | 258 | 364 | 450 |
| 8 | 153 | 211 | 265 | 375 | 460 | 527 | 750 | 923 |
| 9 | 205 | 290 | 355 | 503 | 617 | 712 | 1006 | 1240 |
| 10 | 267 | 378 | 463 | 655 | 803 | 926 | 1310 | 1613 |
| 12 | 422 | 596 | 730 | 1033 | 1273 | 1468 | 2076 | 2554 |
| 15 | 740 | 1021 | 1282 | 1818 | 2224 | 2464 | 3617 | 4467 |
| 18 | 1168 | 1651 | 2022 | 1860 | 3508 | 4045 | 5704 | 7047 |
| 24 | 2396 | 3387 | 4155 | 5874 | 7202 | 8303 | 11744 | 14466 |
| 27 | 4407 | 6211 | 7674 | 10883 | 13257 | 15344 | 21770 | 26622 |
| 30 | 5906 | 8352 | 10223 | 14298 | 17717 | 20204 | 28129 | 35513 |
| 36 | 9700 | 13769 | 16816 | 23760 | 29284 | 33722 | 47523 | 58406 |
The discharge rate is based on clean water and half filled pipes.