1. Static Head in metres ...

1. Static Head in metres water press= Ordinance Datum Height (ODH) of the Pipe Invert at the point of discharge minus the ODH of Water level in borehole (The Height Difference)

2. System Head in metres of water = Calculate diameter of pipe to achieve a desired flow velocity from the desired flow rate (1m/s is reasonable), then From tables, calculation spreadsheet or software calculate the flow friction head loss equivalent for the distance of the pipeline.

3. Total Head in metres = 1 + 2

4. Select a borehole pump to deliver the desired flow at the Total Head, this is called The Duty Point

5. From the manufacturers pump curves look for the Duty Point on the flow / head curve and note the corresponding absorbed power (electrical kW)

6. Estimate the annual hours run for the pump (to achieve volume of water required) and multiply that by the Duty Point kW rating to find kWh.

7. Find the unit price per kWh from the energy supplier and multiply by the annual kWh calculated to arrive at the cost of electricity per year. Add any standing charge costs for the electrical supply and metering.

8. Add in some costs for pump maintenance each year to 7. to arrive at your total cost.