Noise Loggers for Water Leak Detection

A noise logger is a battery-powered acoustic sensor fixed to a pipe, valve or hydrant in a water network. During the quiet early-morning hours it records the sound and vibration travelling through the pipe wall. A genuine leak produces a continuous, characteristic noise; the logger analyses the sound level and consistency each night and flags pipes where leak noise is present, so crews can investigate a small area instead of the whole network.

A noise logger listens at a single point and reports whether leak noise is present nearby. A correlator (or correlating logger) compares the sound arriving at two points and uses the time difference to calculate the leak's position between them. Many modern loggers do both — logging nightly and correlating with neighbouring units to pinpoint the leak.

Permanent loggers stay in priority zones and report every night over NB-IoT, LoRaWAN or cellular, catching new leaks within days. Lift-and-shift loggers are moved area by area for periodic surveys at lower hardware cost. Utilities running active leakage control usually combine both: permanent loggers on critical or historically leaky zones, lift-and-shift for routine sweeps.

Accelerometers couple to the pipe wall and work well on metal and asbestos-cement pipe. Hydrophones detect the pressure wave directly in the water and perform far better on plastic and large-diameter mains, which transmit structure-borne sound poorly. For mixed or plastic networks, hydrophone-capable loggers find leaks that accelerometers miss.

NB-IoT uses licensed cellular spectrum with strong penetration into underground chambers and needs no network of your own, which suits scattered or deep-chamber deployments. LoRaWAN is cheaper to run where you already operate gateways and suits dense urban roll-outs. The right choice depends on chamber depth, density and whether you want to own the network.

Detection reliability depends on pipe material, logger spacing, background noise and sensor type. On metallic networks with correctly spaced loggers, leak presence is detected with high confidence; correlating loggers then position the leak typically within a metre or two over moderate spacings. Plastic and large-diameter mains are harder and benefit from hydrophone sensors and tighter spacing.