Hey Sigurd,
I have been drinking a lot of water too on my Adderall therapy but not 3 liters and hour!!!! Wow, that's a lot!! Be careful, too much water can hurt you...remember that lady that drank too much water in that radio competition to win the Nintendo Wii?!!
Just make sure you check with your doc about that. Once, when I was on a weight loss stint of mine, I was drinking too much water and it messed up my electrolyte balance. I had irregular heart beats and I was lightheaded. My doctor said that much water was really dangerous.
Good luck!! Maybe try some gatorade once in a while?