At first, you don't miss it that much. It hits you in a detached way: yes, you have no water, but you're not that thirsty, are you?
You try to cope, remind yourself that you don't need water to live, you can get by on: papaya juice, watermelons, soups, milkshakes...
But at some point, you just crave, crave a glass of water. Just to remember how it tastes like, how that cool liquid feels like sliding down your throat. That familiar pleasure which you took for granted, for so long.
And you realize you cannot have water, and never will again. Never see it, never taste it. And even worse, your crystal-clear memories will soon fade like old pictures.
It gets better, maybe, as you learn to live without. But I don't think you ever forget, and remembering brings more pain than joy.