The increasing use of plastic materials has modified several aspects of design and management of water distribution systems. With reference to the numerical modeling of transients, the definition of a correct rheological model of the pipe material is receiving an increasing interest. In this paper the behavior of the molecularly oriented polyvinyl chloride (PVC-O) pipes during transients is investigated, by means of tests on a PN16 DN110 pipe installed at the Water Engineering Laboratory of the University of Perugia, Italy. Pipe characteristics, such as wave speed and Kelvin–Voigt parameters, are estimated by the comparison of experimental and numerical results. Analyses are performed both in time and frequency domain. The variation in time of the wave speed is investigated. The results show that, while the wave speed value is close to that of other polymeric material pipes, such as Polyethylene, the viscoelastic behavior is less evident for PVC-O pipes. This feature is of particular interest for research purposes in laboratories and for current use in functioning systems.