This powerpoint presentation begins by providing the study objective: to summarize the overall approach for the Bioterrorism Risk Assessment (BTRA) waterborne contamination model used to evaluate the risk associated with the purposeful contamination of water using biological agents. The BTRA technical approach is presented, along with the BTRA water contamination model, dissemination scenarios, water network distribution assumptions, BTRA water contamination agents, agent decay, ingested infectious/intoxicating dose, and water model consequences. Presentation summary includes the following: the model is general enough to approximate to a broad range of city water systems or commercial buildings, and accounts for losses due to chlorinated water systems and mixing in the pipes; and, the model is only as good as its input and assumptions. Data gaps exist and introduce large uncertainties, including: decay kinetics of all agents which can be impacted by numerous factors including chlorine, biofilms, pipe materials, etc; human ingested infectious/intoxicating doses of some agents; and, decontamination costs. Includes figures.