The AquaPing is an ultra-low power smart sensor that provides isolated water leak detection, even behind walls without contact with pipes. All signal processing and analysis happens at the edge, so no audio is streamed to the cloud and eavesdropping is impossible.
Broadband high frequency acoustics are emitted when pressurized watre escapes from seams, cracks or loose fitting in pipes. These signals can travel 10 m or more in free space and be detected by the remote sensor, which shows that a stand-off method for water leak detection that is substantially different compared to conventional contact moisture sensors and various types of smart flow meters installed on or inside of plumbing lines.
Acoustic leak detection combines the principles of glass breakage and smoke detectors. Glass breakage occurs on timescale of seconds or less, and requiring continuous data acquisition at rates approaching 1kHz or more. Most plumbing leaks are persistent, which allows for Sub-Hz sampling rates and exceptional battery life.
The advantage of glass breakage is that it is usually loder than the surrounding environment, so the sensitivity of the detector is not a problem. Small water leaks, especially when separated from the sensor by acoustic barriers such as walls, may be at or below the environmental background. Higher sensitivity and noise reduction are essential. This is addressed through mechanical, electronic and digital filtering along with judicious use of statistical analysis.
Acoustic sensing can be used to complement standard leak detection techniques and is especially useful when monitoring large areas. Expected use cases include smart homes and buildings, security systems, irrigation, dental and medical offices, critical plumbing installations, insurance loss mitigation, and water conservation. Other creative uses are up to you!
This acoustic method of water leak detection works well, but cannot identify all possible water problems. For example, it won't react to leaking roofs or melting ice. The nature of the pressurized office is also important. A smooth hole drilled in a pipe will produce a Laminar flow jet with a much weaker acoustic signal than a jagged crack or loose fitting at the same back pressure.
This project is fully open source and welcomes your input. You can find all hardware files, firmware and docs in our GitHub repository. Also available is an example sketch and documentation for interfacing with an ESP8266 master controller using the Arduino IDE.
This project is going to crowdfunding on CrowdSupply, go to support it if you are interested.
