This paper presents application of differential equations in modelling and simulation tests of water supply network pumps drive system together with powered water supply pipelines. The description is preceded with an analysis of practically applicable mathematical models representing drive systems with induction motors and PWM converter. Models of electric devices and their elements, from the viewpoint of the methods used to describe the phenomena occurring in them, can be divided into three basic groups: circuit models, semi-field models, and field models. Each of these groups has its own purpose depending on the complexity of the modelled electric system, the types of devices, and the required accuracy in the reconstruction of processes actually occurring in the system. In the case under consideration, sufficient accuracy is ensured by circuit models. Mathematical models of PWM converter, squirrel-cage induction motor, and pump together with a pipeline allow to carry out computer simulations of the whole drive system consisting of the above-listed elements. Simulations of the system of such complexity definitely pose a more difficult problem than simulation of each of the elements performed separately. In the following, mathematical models of individual elements and selected simulation tests of the system are presented. Copyright © 2011 John Wiley & Sons, Ltd.