Abstract
Monitoring for changes in drinking water quality using online sensors has focused on improving the water delivered to consumers. However, recent research has focused on using sensors as one facet of a holistic contamination warning system or simply monitoring for unusual changes that could indicate contamination. This chapter focuses on the following areas: (1) Results on the change of online water quality parameters to contamination in drinking water. Total organic carbon and free/total chlorine (in chlorinated/chloraminated water, respectively) are often presented as the most effective online-monitoring parameters, so the benefits and gaps of these parameters are discussed; (2) The role that event detection software and algorithms play in analyzing online water quality data for unusual changes; (3) The challenge of high operational and maintenance costs for online sensors within a water distribution network; and (4) The future of online water quality monitoring.