The water has become pink in saturation and due to some chemicals, every furry who drinks it grows a colossal booty that sloshes and they become incredibly horny and slutty.

(I was bored and horny, cut me some slack on this one)

Update: new intro where you already drank some of the water

Update 2: new intro where it's up to you whether you drank the water or not and how big your ass got and how horny you got