The total number of known bacteria, eukaryotes, and viruses that pose a threat to human health is more than one hundred. At least half of these are relevant to water and food safety. Their control in water has been most economically achieved through the use of indicator organisms and treatment technologies. To regulate individual microorganisms, if and when necessary, tools to prioritize the above list of microorganisms with respect to their potential to cause harm must be available. Evaluation and establishment of virulence-factor activity relationships (VFARs) has been suggested as one approach to accomplish this prioritization. VFARs can be defined as a set of relationships (expected and to be established) between distinguishing informational and functional molecules and the corresponding virulent activity of microorganisms- modulated by environmental and host-related factors. Evaluation of the existence and extent of such relationships requires dedicated informational databases and high throughput experimental tools (e.g., DNA biochips). We are evaluating a pilotscale database for this purpose focusing on selected examples of bacteria, eukaryotes, and viruses. We are also evaluating the design and fabrication of a VFAR biochip to be validated for waterborne pathogens. The work presented here summarizes the main characteristics of this database. It also discusses the issues related to the development of the VFAR biochip including probe design, specificity, sensitivity, detection limit, target amplification, reliability, and sample processing. The information gained through the development of this database and the biochip may be used in designing microarrays to detect hundreds to thousands of virulence factors irrespective of the host microorganisms.