Explore innovative approaches to residential water conservation in this 2012 lecture by Jon Froehlich at the Center for Language & Speech Processing, JHU. Learn about HydroSense, a novel low-cost water sensing system that infers usage data from individual fixtures using a single sensing point. Discover Reflect2O, a real-time ambient water usage feedback display designed to inform and promote efficient water practices in homes. Examine the development of sensors and inference algorithms, results from in-home evaluations, and preliminary feedback visualization designs. Understand the potential impact of these technologies in reducing residential water consumption by 15-20%, potentially saving billions of gallons and dollars annually. Gain insights into Froehlich's research on creating sensors to monitor human activity and provide feedback to increase awareness and promote environmentally responsible behavior.