Pressure waves as a tool for leak detection

In the last decades, the increase in water demand and the shortage in new easy to exploit quality water resources caused an increasing interest in further groundwater resources. Since leak reduction actually corresponds to the acquirement of new quality resources, water utility managers are realizing that unaccounted-for water has to be considered in plans to increase water supply and leak detection is now considered as a money-saving expense. Within leak detection methodologies, those based on transient analysis can be in some cases faster and cheaper than most of the existing ones. In the paper, first properties of pressure waves in closed single pipe systems are described as well as some results already obtained within the time domain framework are reviewed. Then the emphasis is posed on methodologies based on the analysis of transient tests results in the frequency domain along with the use of the wavelet transform. Finally, special attention is posed on possible pollutant intrusion in pipes through leaks during transients.