Defines pump units consisting of: - one single or several rotodynamic water pump(s), including where integrated in other products, and driven by a motor system, consisting of an electrical motor and - either a terminal box which only enables to operate the pump unit at constant motor stator frequency and thereby (nearly) constant rotational speed, - or a CDM (Complete Drive Module) which enables to operate the pump unit at variable rotational speed depending on a varying demand of flow rate and/or discharge or differential pressure.