My educated guess would be that you accidentally switched the game view from fire (default) to either fancy or blob view.
Now to switch back to fire view, just press "4".
(In case water still appears purple even after switching the view, then either it's decorated or someone really needs a visit to opthalmologist.)
Man i'm not that new to the game lol
But thanks for your guess
Nope, maybe it has to be some problem with my GPU or idk
I asked because I thought that accidentally, I had pressed some special uncommon key combination that changed the color palette (but weirdly, it only affects blue colors)