I have a three liter jug that I carry everywhere with me and I can easily finish it during a workout, especially on leg days. I have to say however, that I drink water like no other. I probably average a liter an hour at least if I had to take a guess.
No I don't see how it could be a problem. Just piss before you start and if your working hard enough then you shouldn't have to piss before the workouts over because you'll be sweating it off as quick as you can drink it (at least this is my experience).