Parallel with new security-related detection needs for water utilities, research in rapid detection techniques for both chemical and biological contaminants is on the verge of producing easy, fast detection of many contaminants. This paper identifies contaminants that may be used in intentional releases into potable water systems, reviews currently available techniques for detecting those contaminants, explores emerging detection technologies and recommends a course of action for water utilities developing a monitoring program. The contaminants identified in the literature as potential threats to potable water are diverse and include spore-forming and non-sporulating bacteria, DNA and RNA virsuses, protozoa and biological toxins, chemical warfare agents, organic chemicals and inorganic chemicals. The general features by which contaminants may be judged as potential threats are presented. Among detectors of replicating biological agents, polymerase chain reaction (PCR) based methods stand out as the only currently available technology capable of detecting the diversity of agents identified as potential contaminants at the sensitivity and in the time frame required. In the absence of a single chemical detector for detection of all potential contaminants, it is recommended that utilities purchase equipment such as chemiluminescence or bioluminescence test kits for field testing in the event of a suspected release and develop pilot monitoring programs to pave the way for implementation of improved chemical monitors as they are developed. Includes 47 references, tables, figures.