A critical mass of adopters, a majority of which are usually opinion leaders, is required for the diffusion of any innovation to become self-sustaining. All public wastewater facilities in Vermont and New Hampshire were surveyed to determine which facilities exchange information, which have adopted UV, and what characteristics are common among adopters, non-adopters, and opinion leaders. Two networks, based on the exchange of general information and information about disinfection technology, were constructed using UCINET; they indicate UV has likely been adopted by a critical mass. Opinion leader facilities' employees interact with consultants and vendors. Opinion leader facilities' managers work closely with their staff and are active in professional organizations. Non-adopter opinion leader facilities are fiscally conservative while innovative opinion leader facilities are shaped by decisions of the community's elected officials. Distance between facilities was mapped using GIS software and did not influence the type of disinfection technology adopted
