Dewatering Pump Sizing Calculator

Work out dewatering pump sizing instantly with clear inputs, formula shown and shareable results.

About Dewatering Pump Sizing Calculator

Hydraulic power is flow times head times density times gravity. Dividing by pump efficiency gives shaft power and by motor efficiency the motor rating. Mine dewatering must be sized on peak inflow with standby capacity, because losing dewatering floods the workings and can be catastrophic.

Formulas

Pump power

Hydraulic power (kW) = flow (m3/h) x 1000 x 9.81 x head (m) / 3,600,000

Motor rating

Motor kW = hydraulic power / pump efficiency / motor efficiency

Worked example

With the default values below, Dewatering Pump Sizing Calculator returns Motor Rating Required of 238.071. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mine Water Inflowminimum 0 m3/hour: 250 m3/hour
Total Pumping Headminimum 0.01 m: 180 m
Pump Efficiencyaccepts 1–100 %: 72 %
Standby And Peak Marginaccepts 0–100 %: 30 %

Results

Motor Rating Required: 238.071
Hydraulic Power: 159.413
Design Flow: 325.00
Energy Per Cubic Metre Pumped: 0.6813

Step by step

1Values used
2Pump power
3Motor rating
4Motor Rating Required= 238.071
5Hydraulic Power= 159.413
6Design Flow= 325.00
7Energy Per Cubic Metre Pumped= 0.6813

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Loss of mine dewatering can cause flooding and loss of life. Dewatering systems require redundancy, standby power and monitoring under the mine's emergency plan.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Loss of mine dewatering can cause flooding and loss of life. Dewatering systems require redundancy, standby power and monitoring under the mine's emergency plan.

Frequently Asked Questions

Why such a large standby margin?

Inflow varies with rainfall and with intersection of new water-bearing structures, and pumps fail. Standard practice is full standby capacity, not just a margin, on critical dewatering duties.

Does staging help on high heads?

Yes. Multistage pumps or booster stations in series keep individual pump pressures within casing limits and allow flexible operation as the mine deepens.