This bug was fixed in Patch 1.55.105.
My shower was broken but I repaired and even deleted it. Despite this the annoying noise doesn’t go away
The issue seems to occur for the In Or Out? – Outdoor Shower from Island Living only.
To get rid of the noise, you need to completely reboot the game. There isn’t anything else you need to do. Simply close down Sims 4 and restart it.
How to prevent
Use a different shower.