The U.S. Environmental Protection Agency's (USEPA) Threat Ensemble Vulnerability Assessment (TEVA) Research Program was established to develop software tools for consequence assessment of contamination events in drinking water. Recently, additional tools have been developed for designing and evaluating early warning systems, and predicting the likely costs and benefits. This paper presents the capabilities of the TEVA Computational Framework for modeling realistic early warning systems for distribution systems, and some of the results of recent studies. The goals of the TEVA Research Program are: to develop, optimize, and make available to water utilities a suite of software tools for drinking water distribution system security; and, to use the TEVA system to design, implement, and test a contamination warning system in a utility distribution system. Topics discussed include: the TEVA computational framework; contamination warning systems (CWS) architecture studies; routine sampling for contaminants; ideal sensors and chlorine sensors; and, water quality sensors, customer complaints, and public health surveillance as broad spectrum sensors. Includes 20 references, figures.