Calibrated Acoustic Leak Signatures in Pressurised Plastic Water Pipes: A Laboratory Analysis

Despite decades of research, there is still a lack of calibrated data on acoustic leak signatures typical of common types of water supply pipes. This study addresses this gap by providing leak signatures recorded with calibrated, high-sensitivity accelerometers in a controlled laboratory environment. The study also investigates how different leak configurations at nominal static pressures of 2.8-4.2 bars influence the power spectrum of the pipe-wall acceleration. The results show a great variability, i.e., 5 orders of magnitude, in the power spectrum. The amplitude and shape of this spectrum depend on whether the leak is through a valve-controlled nozzle, hole directly drilled in the pipe wall, or a longitudinal or traverse slit. The coherence in the leak signals as a function of the distance between the accelerometers is determined and used to estimate the leak signal attenuation. Crucially, the results reveal that longitudinal slits, which represent the most common failure mode in plastic pipes, produce the weakest acoustic signals, making them difficult to detect and locate using standard acoustic equipment. It is expected that the calibrated data collected from this study will support high-fidelity computer simulations and development of better signal processing algorithms to predict and to detect hidden leaks in water distribution networks in the presence of background noise and high acoustic attenuation. The recorded data are made available to a wider community through a dedicated data depository.