Hazen-Williams C Values Table: Complete List by Pipe Material (2026)
Complete Hazen-Williams C coefficient table for PVC, steel, cast iron, copper, HDPE, concrete, and more. Includes values for new and aged pipes.
What is the Hazen-Williams C Coefficient?
The Hazen-Williams C value (also called the roughness coefficient) is an empirical constant that represents the internal smoothness of a pipe. Higher C means smoother pipe and lower friction losses.
The Hazen-Williams equation for head loss:
hf = 10.67 × L × Q^1.852 / (C^1.852 × D^4.87)Where:
- hf = friction head loss (m)
- L = pipe length (m)
- Q = flow rate (m³/s)
- C = Hazen-Williams coefficient
- D = inside diameter (m)
Complete C Values Table
| Pipe Material | C (New) | C (10 years) | C (20+ years) |
|---|---|---|---|
| PVC (polyvinyl chloride) | 150 | 145 | 140 |
| CPVC | 150 | 145 | 140 |
| HDPE (high-density polyethylene) | 150 | 150 | 145 |
| Polypropylene | 150 | 145 | 140 |
| Copper (smooth) | 150 | 140 | 130 |
| Aluminum | 130 | 125 | 120 |
| Galvanized steel (new) | 120 | 100 | 90 |
| Commercial steel | 120 | 110 | 100 |
| Welded steel (riveted) | 110 | 95 | 85 |
| Cast iron (new) | 130 | 110 | 90 |
| Cast iron (encrusted) | 100 | 85 | 70 |
| Ductile iron (new) | 140 | 130 | 120 |
| Concrete (smooth) | 130 | 120 | 110 |
| Concrete (rough) | 110 | 100 | 90 |
| Asbestos cement | 140 | 130 | 120 |
| Glass | 140 | 140 | 140 |
| Brass | 135 | 130 | 125 |
| Lead | 130 | 120 | 110 |
| Wood (stave) | 120 | 110 | 100 |
| Fiberglass (FRP) | 150 | 145 | 140 |
Guidelines for Selecting C
New installations
Use the "New" column. When designing a system from scratch with factory-fresh pipe, catalog C values apply.
Existing systems
If you're sizing a pump for an existing system, use the C value matching the pipe age. A common rule: reduce C by 15-20% from the factory value if the pipe age is unknown.
Conservative designs
For critical systems (fire protection, hospitals), use the aged C value even for new pipe. This builds in a safety margin for future deterioration.
Limitations of Hazen-Williams
- Water only. Does not apply to other fluids.
- Turbulent flow only. If Reynolds number < 2300 (laminar flow), use Darcy-Weisbach.
- Temperature range: Valid for 5°C to 25°C. Outside this range, viscosity changes significantly.
- Velocity range: 0.6 to 3 m/s. Above 3 m/s, errors can exceed 10%.
For conditions outside these limits, use the Darcy-Weisbach equation with the Swamee-Jain friction factor.
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