Shower scenes are always tricky for various reasons: It has to look like a real shower, there has to be room for a camera, the water has to be real, the actor(s) have to look like they are naked, the faucets, shower head, and sometimes even the drain all have to look like they work and last but not least in black and white the chocolate syrup has to look like blood! Well, only in Hitchcock's "Psycho" for the chocolate sauce part.
So the actual construction can be of the masonite shower board, plastic tile or actual ceramic tile. Unless it is a large shower or unless it's just an overhead shot, or something close enough that can be done with the shower door open, one (or more) of the walls have to be wild to see what's going on--or not as the case may be! 99.9% of the time the actor(s) are not really naked. Sometimes uninhibited women will go topless. Onetime on "Mighty Joe Young" Charlene Theron lifted up her t-shirt at lunch, but that has nothing to do with shower scenes. In the case of actual (or partial) nudity, all non-necessary people are cleared from the set. That's called a "closed" set and only the actual cameraman, director, and sound people might be there. I did the last season of "Dante's Cove" a couple of years ago and there were lots of "closed sets" even though everything was "simulated" and the actors were wearing socks that weren't on their feet..........lol
The running water, drainage, and steam are all controlled by special effects--even the heating of the water. The actor might turn the faucet which may or not actually control the water flow depending on what the scene is. The actual purchase of the faucets and shower head (as well as the other bathroom fixtures such as towel bars) are all set dressing. Sometimes special effects or the art department construction might install them--sometimes set dressing will and special effects will then hook them up. There are fog / water filters for the camera--although sometimes the fog is desirable for concealment purposes! Showers have to be built up unless the stage has a drain or pit for the water to drain. It's similar when a sink is also used, but with obvious less complications. So the next time you see an actor turn on the water on a set or take a shower, you'll know there is a lot more work involved.
Next week we'll continue our plumbing discussion with staged toilet simulations. (no we won't!)