pumps

1) duty point. (flow, head)

2) NPSH calculations.

3) Terrain dictated pump type.

4) Driver and RPM of driver. (direct coupled always better than V drive)

5) Efficiency, serviceability Etc.

More than one calculation need to be compared to end up with the most economical setup. (For example bigger piping vs cheaper running costs - discounted over the life of the equipment).

The temperature and viscosity of the water must also be known.