Pipework - Carrying Capacity of Sewer and Wastewater Pipes

Carrying capacity of sewer and wastewater pipes

The diagram below can be used for design of sewage and wastewater gravity conveying systems where capacities in litres per second and the slopes of the pipe lines are known.

Drain Pipe Capacity - SI Units - litre per second

Note - the charts are based on clean pipes, clean water and half filled pipes. Friction coefficient may vary with pipe material.

Carrying Capacity of Sewer Pipe (litres / second)
Size of pipe (inches)	Decline per 100m of pipe (m)
	1	2	3	6	9	12	24	36
3	0.82	1.20	1.45	2.02	2.52	2.90	4.04	4.98
4	1.70	2.40	2.97	4.16	5.11	5.87	8.26	10.28
6	4.73	6.62	8.14	11.55	14.13	16.28	22.96	28.39
8	9.65	13.31	16.72	23.66	29.02	33.25	47.32	58.23
9	12.93	18.30	22.40	31.73	38.93	44.92	63.47	78.23
10	16.85	23.85	29.21	41.32	50.66	58.42	82.65	101.76
12	26.62	37.60	46.06	65.17	80.31	92.62	130.97	161.13
15	46.69	64.41	80.88	114.70	140.31	155.45	228.20	281.82
18	73.69	104.16	127.57	180.44	221.32	255.20	359.87	444.60
24	151.16	213.69	262.14	370.59	454.37	523.84	740.93	912.66
27	278.04	391.85	484.15	686.61	836.38	968.05	1373.47	1679.58
30	372.61	526.93	644.97	902.06	1117.77	1274.67	1774.66	2240.52
36	611.97	868.69	1060.92	1499.02	1847.53	2127.52	2998.23	3684.83