https://www.jsonline.com/story/life/green-sheet/2020/02/25/why-bubbler-what-water-drinking-fountain-called-wisconsin-milwaukee/4793730002/
Although "bubbler" and "drinking fountain" seem to have been used interchangeably, "bubbler" is the word that stuck in Milwaukee's cranium — and, as important, in our self-identity. By the early 1960s, news reports highlighted the fact that calling a bubbler a bubbler was the sure sign of being a Milwaukeean.
"Why Milwaukee uses this term … is hard to say. Possibly it is a survival of the old German habit of making words sound like what they represent," the Racine Journal-Times wrote in a 1963 editorial reprinted in both The Journal and Sentinel. "But the word has a certain charm, and we hope Milwaukee keeps it."