It is striking how profoundly we have come to integrate technological artifacts into our lives and how commonplace these devices appear to us now. There were times when they were entirely new. Just think of indoor water taps replacing public wells, or electric light bulbs supplanting kerosine lamps and gas fixtures. Here I consider how new technologies associated with engineered water supplies became a part of standard household practice in the late nineteenth and early twentieth centuries. Specifically, I explore the role that knowledge played in the process in Los Angeles. This city offers a thought-provoking glimpse into the “appropriation of technology” around 1900.