In Star Trek, we saw both water showers, as well as sonic showers. Sonic showers were used from TNG onward, if I am correct, but at the same time I must think, did any ships have water showers equipped?
Think about it. In Voyager, Neelix took a water bath. This would suggest that a water shower might be available to those who want it. Anybody agree, or have any information?
Depends on how much you want to take into your personal view on the Trekverse. For instance, going back to the old novels, some had Kirk use a water shower while others a sonic shower. This suggests two settings or perhaps an upgrade. Some fans have suggested that Both are used simultaneously. Treknically sonic showers first appeared in blueprints (either the Klingon Battle Cruiser or Romulan Bird of Prey, by Michael McMaster) in the 1970s. This only makes sense since sonic showers are rather direct, simplistic, solid-state, and quite fitting for Klingons (who originally had sonic-everything in TOS: sonic disruptors, sonic force fields, sonic grenades etc.).
The first literary reference was in a short story I came across in Enterprise Incidents, but I could be mistaken...