perhaps if you were more comfortable and got better quality sleep, you wouldnt wake up in the middle of the night to begin with.
better quality sleep=a deeper sleeping state
i used to get up 1 or 2 times a night when i was sleeping on a bed i thought i liked.
i changed the matress and find that i get better sleep on it. i dont wake up in the middle of the night anymore, but i have to "wee" right when i wake up.
if i were you, i wouldnt stop drinking water at night, mayb drink less at night than in the morning if waking up is going to hurt your sleeping.