Risk Reduction and Sensor Network Design

Contamination warning systems (CWS) are a promising approach for detecting contaminants in drinking water systems in time to allow for the effective reduction of public health or economic impacts. In this work, the authors utilize TEVA-SPOT, the Threat Ensemble Vulnerability Assessment and Sensor Placement Optimization Tool, to address one of the most significant outstanding questions about sensor network design: how many sensors are needed in a water distribution system to reduce the risk of contamination incidents? Previous work has assumed that the number of sensors was determined prior to optimization for the best locations, and was typically limited by budget constraints. In this paper, the authors use network models for several different water utilities that range in size from small to large systems. Sensor network designs are developed that minimize several objectives of concern to water utilities. The number of sensors needed is a question of acceptable risk and is shown to be dependent on the detection goals of the community, utility-specific hydraulics, the sensor technology, and the speed at which an effective emergency response can be achieved. The implications of these results to the widespread applicability and sustainability of CWS will be discussed.