Method: Hazen–Williams (SI form). Q in m³/s, D in m, C as selected. Water at ~20 °C (ρ = 1000 kg/m³).
Checks: ft/100 ft = 100 × J (exact); Pa/m = ρ g J; psi/100 ft = (Pa/m × 30.48) / 6894.76.