Once central figures in American public health, waterworks engineers are no longer involved in many decisions made about the public water supplies. This paper argues that the profession's response to the early fluoridation movement of the 1940s and 1950s marked a change in the relationship between waterworks engineers and the other constitutive groups in public health and contributed to the disenfranchisement of the waterworks profession. Sensing a potentially divisive issue, two leaders of the profession, Abel Wolman and Linn Enslow, took steps they hoped would prevent a rift within the profession and allow waterworks engineering to continue its association with the wider public health community. Although the leaders saw the fluoridation issue differently, neither encouraged the profession to consider it openly or to take up the broader question of what limits, if any, should be placed on treating water supplies to meet human needs. Instead, they opted to locate authority for fluoridation outside the waterworks profession with dentists, doctors, and public health administrators. As a result, waterworks engineers conceded a great deal of the status and prestige associated with decision-making roles in community health issues and have largely faded from view.