Tools
Water and wastewater engineering calculators
Free calculators for water and wastewater engineering. Each one runs in the browser, shows its working, and cites the equations and data it uses, so you can check the answer against your own design standard.
Calculators
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Hydraulics
Pipe pressure drop and head loss calculator
Friction head loss and pressure drop for water in a full pipe: Darcy-Weisbach with Colebrook-White, fittings, static lift and a Hazen-Williams cross-check.
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Pumping
Pump head, NPSH and power calculator
Total dynamic head, NPSH available, flange pressures, power and energy cost for a pumped water system, with system and pump curves, operating point and VSD speed.
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Drainage
Sewer and drain pipe capacity calculator
Full-bore and part-full capacity and velocity of a gravity sewer by Colebrook-White, checked against the Water UK Design and Construction Guidance.
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Flow measurement
Weir flow calculator
Flow over 90° V-notch and rectangular weirs from head, or head from flow, with weir loading rate for clarifier and DAF launders.
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Water reuse
Rainwater harvesting tank size calculator
BS 8515 simplified tank sizing from collection area, rainfall and non-potable demand, with the share of demand met and mains water replaced.
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Storage
Tank volume and dip table calculator
Volume at any depth, depth for a volume and a dip table for vertical, cone-bottom, horizontal and rectangular tanks.
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Wastewater
Storm overflow spill volume and pollution calculator
Turn storm overflow spill hours into an estimated volume of storm sewage and the BOD, ammonia, solids, phosphorus and E. coli it carries.