Wireless Sensors for Measuring Drinking Water Quality in Building Plumbing: Deployments and Insights from Continuous and Intermittent Water Supply Systems

Despite continued calls to increase the monitoring of drinking water systems, few communities and utilities have adopted modern, distributed, and real-time monitoring systems. Measurements of drinking water quality are often only made at the treatment plant, with limited grab sampling taking place throughout the distribution system. At the building level, where most of the public's exposure to drinking water takes place, the capacity to make continuous measurements to characterize water quality dynamics has been almost impossible. Innovation in sensors, microcontrollers, and data services is underpinning a broader smart cities movement, but their value as a tool in the management of drinking water systems is still unclear. In this paper, we present a new open-source wireless sensor platform, which allows water quality to be measured at the tap. Our internet-connected devices transmit data back to cloud hosted services, where they can be analyzed in real-time. We provide examples of large-scale deployments within buildings in Ann Arbor, Michigan, USA and Mexico City, Mexico. In each of these studies, we demonstrate the detection of phenomena that would have been missed through existing, low-throughput monitoring approaches. The deployment in Ann Arbor emphasizes the importance of real-time measurements in a drinking water distribution system, highlighting shifts in neighborhood-scale electroconductivity (a proxy for total dissolved solids) that would have been missed as part of established sampling procedures. The Mexico City deployment demonstrates highly variable water quality and supply in intermittent systems and characterizes the variability of chlorine concentrations between continuous and intermittent portions of the city.