Stormwater Conductors

Capacity roof drains

Capacity of horizontal sloped and vertical stormwater and rainwater leaders are indicated below:

Imperial Units

Pipe Size NPS (in) Vertical Roof Drains (gpm) Horizontal Sloped Pipe (gpm)
Slope 1/8 (in/ft) Slope 1/4 (in/ft) Slope 1/2 (in/ft)
3 90 35 50 70
4 190 80 110 157
5 360 140 200 280
6 560 225 315 450
8 1200 480 680 950
10 860 1220 1728

Metric Units

Pipe Size DN (mm) Vertical Roof Drains (l/s) Horizontal Sloped Pipe (l/s)
Slope 1 (cm/m) Slope 2.1 (cm/m) Slope 4.2 (cm/m)
80 5.8 2.1 3.0 4.3
100 12 4.9 6.9 9.9
125 23 8.8 12 18
150 35 14 20 28
200 76 30 43 60
250 54 77 109

Related Topics

  • Water Systems - Hot and cold water systems - design properties, capacities, sizing and more

Related Documents

Tag Search

  • en: storm water roof drain rainwater rainfall leaders

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