Irrigation Mainline Loss
Hazen-Williams friction loss, net head and velocity check — pvc mainline.
Long PVC mains to distant fields quietly eat pump head — 300 m at high velocity can cost 10+ m. The fix is diameter, not a bigger pump: friction falls with the 4.87th power of bore.
PVC mainline: friction loss scales with the 4.87th power of diameter — one pipe size up typically cuts the loss by 60%. For hydro, lost head is lost power forever; for pumping, it's a permanently bigger electricity bill. Buy diameter once instead.
Engineering estimate from published standards and typical equipment data. Site conditions, equipment datasheets and measured data govern the real result — confirm with a qualified engineer.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Use the free Irrigation Mainline Loss online — Hazen-Williams friction loss, net head and velocity check — pvc mainline. Runs instantly in your browser: no signup, no upload, mobile-friendly.
About Irrigation Mainline Loss
Long PVC mains to distant fields quietly eat pump head — 300 m at high velocity can cost 10+ m. The fix is diameter, not a bigger pump: friction falls with the 4.87th power of bore.
How to use Irrigation Mainline Loss
- 1Enter pipe length, inner diameter and flow.
- 2Pick the pipe material.
- 3Read friction loss, remaining head and the velocity verdict.
Why use Irrigation Mainline Loss?
- ✓Hazen-Williams with material-correct roughness coefficients
- ✓Velocity check warns against erosion and hammer territory
- ✓Net-head output feeds straight into hydro/pump decisions
- ✓The diameter lesson: one size up cuts loss ~60%
Frequently asked questions
How much head do I lose to pipe friction?+
Hazen-Williams: loss scales with length, flow^1.85, and — brutally — diameter^−4.87. 200 m of 110 mm HDPE at 8 L/s loses ~3 m; the same flow in 90 mm loses ~7.5 m. For hydro that's power gone forever; for pumping it's a permanently fatter bill. The tool runs your exact case.
What pipe velocity is acceptable?+
Design comfort: 1–3 m/s. Below 1, you've overspent on diameter (and sediment may settle); above 3, friction soars, erosion accelerates, and water hammer on valve closure becomes violent. The velocity readout here flags both ends.
Is bigger pipe worth the extra cost?+
Almost always over the system's life: the next standard diameter typically cuts friction loss ~60%, repaying its premium in saved pumping energy within a few years — or in permanently higher hydro output. Buy diameter once; buy losses forever.
Which C value should I use?+
Material and age: new HDPE/PVC ≈150, new steel ≈130, old rusted steel ≈100, concrete ≈120. Aging matters — a 20-year-old steel line at C=100 loses nearly twice what its installation calculations promised. When relining or replacing, this delta IS the business case.
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