Stormwater Drains Capacity
Reference data and engineering information about stormwater drains capacity for piping systems applications.
stormwaterdrainscapacityCalculator
Overview
Engineering reference data for Stormwater Drains Capacity in piping systems.
Key Formulas
Continuity
Mass conservation in pipe flow.
Pressure Drop
Darcy-Weisbach equation.
Pipe Area
Cross-sectional area of a pipe.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Pipe diameter | m | |
| Flow velocity | m/s | |
| Pressure drop | Pa | |
| Friction factor | — |
Stormwater Conductor Capacities
The following tables provide capacities for horizontal sloped and vertical stormwater and rainwater leaders based on pipe size and slope.
Imperial Units
6 rows
Pipe Size (NPS)(in) | Vertical Roof Drains(gpm) | Slope 1/8(gpm) | Slope 1/4(gpm) | Slope 1/2(gpm) |
|---|---|---|---|---|
| 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 |
Source: engineeringtoolbox.com
Metric Units
6 rows
Pipe Size (DN)(mm) | Vertical Roof Drains(l/s) | Slope 1(l/s) | Slope 2.1(l/s) | Slope 4.2(l/s) |
|---|---|---|---|---|
| 80 | 5.8 | 2.1 | 3 | 4.3 |
| 100 | 12 | 4.9 | 6.9 | 9.9 |
| 125 | 22 | 8.8 | 12 | 18 |
| 150 | 36 | 14 | 20 | 28 |
| 200 | 76 | 30 | 43 | 60 |
| 250 | 54 | 77 | 109 |
Source: engineeringtoolbox.com
Pipe Materials and Standards
Building Storm Sewer Pipes
9 rows
Piping Material | US Standards |
|---|---|
| ABS plastic pipe (Schedule 40, DR 22, DR 24) | ASTM D2661; ASTM F628; ASTM F1488; CSA B181.1; CSA B182.1 |
| Cast-iron pipe | ASTM A74; ASTM A888; CISPI 301 |
| Concrete pipe | ASTM C14; ASTM C76; CSA A257.1M; CSA A257.2M |
| Copper or copper-alloy tubing (Type K, L, M or DWV) | ASTM B75; ASTM B88; ASTM B251; ASTM B306 |
| Polyethylene (PE) plastic pipe | ASTM F667; ASTM F2306/F2306M; ASTM F2648/F2648M |
| Polypropylene (PP) pipe | ASTM F2881; CSA B182.13 |
| PVC plastic pipe (DWV, SDR26, SDR35, SDR41, PS50, PS100) | ASTM D2665; ASTM D3034; ASTM F891; ASTM F1488; CSA B182.4; CSA B181.2; CSA B182.2 |
| Vitrified clay pipe | ASTM C4; ASTM C700 |
| Stainless steel drainage systems, Type 316L | ASME A112.3.1 |
Source: engineeringtoolbox.com
Subsoil Storm Sewer Pipes
5 rows
Piping Material | US Standards |
|---|---|
| Cast-iron pipe | ASTM A74; ASTM A888; CISPI 301 |
| Polyethylene (PE) plastic pipe | ASTM F405; ASTM F667; CSA B182.1; CSA B182.6; CSA B182.8 |
| PVC Plastic pipe (sewer pipe, SDR35, PS25, PS50, PS100) | ASTM D2729; ASTM D3034; ASTM F891; CSA B182.2; CSA B182.4 |
| Stainless steel drainage systems, Type 316L | ASME A112.3.1 |
| Vitrified clay pipe | ASTM C4; ASTM C700 |
Source: engineeringtoolbox.com
Key Design Considerations
- Vertical roof drains provide significantly higher capacity than horizontal sloped pipes for the same pipe size
- Pipe slope directly affects horizontal pipe capacity — steeper slopes yield greater flow rates
- Pipe material selection should comply with applicable ASTM, CSA, or ASME standards for the intended application
- For building storm sewers, a wider range of materials is available compared to subsoil applications