To provide permanent leakage monitoring, the Von Roll Classic Logger (noise loggers) are installed in water supply network such that both incoming lines and the distribution network are monitored comprehensively for leakage noise. It is necessary in the night between 02.00 and 04.00 o’clock when consumption is at its lowest. The Von Roll Classic Loggers are equipped with a microprocessor and intelligent software which decide on the state of leakage directly after the measuring period ends. Locations where leakage occurs are immediately recognised and are stored ready for reading-out by the water supply utility using the mobile phone network.