Horizontal Storm Drain Piping

Capacities of horizontal storm drain piping systems. Calculates the area to be drained based on drain pipe diameter and slope. Based on rainfall intensity of 100 mm/hour (4 inches/hour).

Calculator

Inputs

Drain Pipe Diameter

Pipe Slope (%)

Results

Area to be Drained-- m²

Area to be Drained-- ft²

Diameter (mm)	Diameter (in)	1% Slope (m²)	1% Slope (ft²)	2% Slope (m²)	2% Slope (ft²)	4% Slope (m²)	4% Slope (ft²)
80	3	75	820	110	1180	150	1620
100	4	175	1880	245	2640	350	3770
150	6	495	5350	700	7550	995	10700
200	8	1070	11500	1515	16300	2135	23000

Notes

Based on rainfall intensity of 100 mm/hour (4 inches/hour)
The anticipated rainfall intensity should always be checked with the local authorities
Table values represent the maximum area that can be drained by each pipe diameter at the specified slope
Drained areas may include roofs, paved courtyards, or similar surfaces