Water Booster Pressure Systems (WBPSs) are responsible for supplying water and maintaining pressure in a building pipeline. These systems are potentially useful to offer energetic services required by the System Operator (SO) through demand response, considering the spread use of these hydraulic devices in high-rise buildings. In this article, a dynamic model for a WBPS is developed in order to evaluate it as a flexible load for demand response applications. The model is built from first-principles and tuned with experimental data of air pressure, power consumption and water flow, obtaining an error of 1.11% in the energy demand between the experimental and the simulated data. It is shown that the WBPS can operate as a flexible load by changing the pressure set point. Additionally, it is achieved a flexibility of 27% in the energy power consumption without stopping the water flow in the building and it is shown that WBPS can provide Spinning Reserve Services. Finally, this work proposes an aggregator of systems, based on a Proportional-Integral Gain Scheduling controller, that can track the SO requirements with an error lower than 0.86%. (C) 2017 Elsevier Ltd. All rights reserved.