Leaks may occur at any time and location in a liquid transmission pipeline. One of the significant complexities in the leak detection process arises when the leak happens in a pipeline in the presence of phase change. A set of experiments are conducted on a 374-meter (1227-ft) pipe to examine the performance of CPM-based Leak-Detection algorithms. Different intensities of slack from the bubbly flow to the complete cavitating zone are managed to be present before performing various leak tests in terms of size and location. Flow and pressure values are measured at different locations along the length of the pipeline and used as the initial and boundary conditions or constraint points and fed to the algorithms. Two CPM-based leak detection algorithms are considered. The first algorithm performs the leak detection based on a CPM model, which does not model the hydraulics involving phase change. The second algorithm takes advantage of a CPM solver with a precise model to take phase change (cavitation) and the presence of vaporous phase (slack) into account. The ability and quality of these leak detection algorithms are examined against the experiments. The results show the importance of the phase change modelling ability of the CPM to avoid false positives and detect the leaks of different types, which would have otherwise been masked under operating conditions that involve phase change.