Water distribution networks (WDNs) are critical infrastructure components in modern society, often experiencing significant degradation, resulting in pre-mature leaks and breaks. It is crucial to perform early detection and localization of small leaks such that corrective actions can be taken promptly, thus mitigating water loss and hydraulic capacity. Most of the acoustic leak detection methods today are passive methods, which are not very reliable in detecting and locating small leaks. This is attributable to attenuation and weak signal-to-noise ratio as leaks themselves may not be associated with significant acoustic energy. In this paper, results from a new active method are presented, which utilizes an acoustic source and hydrophone receivers in a PVC WDN to overcome the issues present in passive systems. A matrix pencil method is applied to experimental data to obtain time delays of signals reflected due to impedance changes in the WDN. The leak-induced time delays are compared to baseline data for detection and localization. Moreover, the power transmission and reflection coefficient are studied for leak detection. Results show that the proposed methods can detect and localize leaks robustly and have significant potential in full-scale WDNs. The trade-off between using single and multiple sensors for leak monitoring is also discussed. The mathematical theory underpinning the experimental findings are also presented to support the experimental observations.