Careful not to confuse with MC-18365. If this behaviour is intended, I get it. However, when placing the water in a water source, it reproduces the sound twice quickly (and this is the bug/annoyance, IMO).

(Also, for any of the Minecraft coders that pass by this bug ticket: this would only make sense if the sound behaviour was consistent. Right now it only hapens when placing source water in water. Stone sound effects are reproduced no matter what block is under/surrounding the water source. I think that it would only be fine if it reproduced either a splash sound or the sound of breaking/walking in the block the water is being added on. Just my two cents.)