VA-Formler

Water & wastewater · Formula library

93 formulas · 45 Norwegian rainfall stations · 23 standards

Formula library
for water & wastewater

Interactive calculators, live visualisations and in-depth articles — based on Norwegian Water Association, NVE and SVV N200 standards. Free, open, no registration required.

Popular formulas

Most used calculators

Gravitasjonsledning (Manning)

v = (1/n) · R^(2/3) · S^(1/2)

Open channel

Trykkledning (Colebrook-White / Darcy-Weisbach)

1/√f = −2·log₁₀(k/3.7D + 2.51/Re√f)

Pressure pipe

Hazen-Williams (vannforsyning)

v = 0.849·C·R^0.63·S^0.54

Pressure pipe

Rasjonell metode (overvann)

Q = C · i(tc) · A · Kf

Stormwater

Fordrøyningsvolum (regnkonvolutt)

V_max = max(V_inn − V_ut)

Stormwater

IVF-kurver (nedbørsintensitet)

i = M·t^(-C)

Stormwater

Live visualisation

Animated flow simulation, Moody diagram, IVF curves, pipe profile and pump characteristic.

45 rainfall stations

Intensity-Duration-Frequency data for all Norwegian climate regions, 2 to 200-year return periods.

PDF + JSON export

Download professional reports with assumptions, validity ranges and references to 23+ standards.

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Formula libraryfor water & wastewater

Popular formulas

Live visualisation

45 rainfall stations

PDF + JSON export

All categories

Formula library
for water & wastewater