Demo: Tethys -- An Energy Harvesting Networked Water Flow Sensor

We describe Tethys, an energy-harvesting wireless water flow sensor that can monitor water use at a per-fixture level with the intention of associating water use with specific individuals. Tethys was motivated by recent efforts at Stanford University to reduce water use due to the California drought. Understanding how the university population uses water at per-person level can greatly influence policies and conservation approaches. Tethys uses Bluetooth Smart to both identify individuals as well as asynchronously upload data to the cloud for later analysis. We describe two challenges encountered in deploying Tethys: energy harvesting design and the mechanical considerations for high-pressure water at high temperatures.