What does the Hazen-Williams C-factor represent in pipe hydraulics?

The C-factor represents internal pipe roughness. A higher C-factor (e.g. 140 for PVC) indicates a smooth pipe with lower friction loss, whereas an older unlined cast iron pipe may have C = 100.

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🚰 Hazen-Williams Pipe Flow & Head Loss Calculator

Calculate pipe velocity (ft/s), friction head loss (ft), and pressure drop (PSI) in water distribution mains.

Pipe Internal Diameter

Inches

Pipe Total Length

Feet

Roughness Coefficient (C-Factor)

C-Factor

Flow Rate Through Pipe

GPM

Friction Head Loss & Velocity

12.08 ft of Head

Pressure Drop: 5.24 PSI | Velocity: 5.11 ft/sec

📝 Hazen-Williams Empirical Steps

Head Loss (ft) = 10.44 × L × Q^1.852C^1.852 × d^4.87

Standard Hazen-Williams C-Factors Reference

Pipe Material	Typical C-Factor	Design Recommendation
PVC / C900 / HDPE	140 – 150	Extremely smooth, minimal scaling
Ductile Iron (Cement Lined)	130 – 140	Standard municipal water main baseline
Concrete Pressure Pipe	120 – 130	Large transmission mains
Old Unlined Cast Iron	80 – 100	Significant tuberculation & friction

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🚰 Hazen-Williams Pipe Flow & Head Loss Calculator

Standard Hazen-Williams C-Factors Reference

📘 Theory & Exam Guide

⚡ Velocity Design Limits

🚰 Related Calculators

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