WATTR: A Method for Self-powered Wireless Sensing of Water Activity in the Home

Tim Campbell, Eric Larson, Gabe Cohn, Jon Froehlich, Ramses Alcaide, Shwetak Patel


We present WATTR, a novel self-powered water activity sensor that utilizes residential water pressure impulses as both a powering and sensing source. Consisting of a power harvesting circuit, piezoelectric sensor, ultra-low-power 16-bit microcontroller, 16-bit analog-to-digital converter (ADC), and a 433 MHz wireless transmitter, WATTR is capable of sampling home water pressure at 33 Hz and transmitting over 3 m when any water fixture in the home is opened or closed. WATTR provides an alternative sensing solution to the power intensive Bluetooth-based sensor used in the HydroSense project by Froehlich et al. [2] for single-point whole-home water usage. We demonstrate WATTR as a viable self-powered sensor capable of monitoring and transmitting water usage data without the use of a battery. Unlike other water-based power harvesters, WATTR does not waste water to power itself. We discuss the design, implementation, and experimental verification of the WATTR device.