During my workouts i usually consume water and have no problem staying hydrated or any issues with my energy levels. On leg day however, this is not the case. After a while, my energy levels get very depleted and i find it a struggle to stay hydrated. Would you suggest i switch over from just water to, water with bcaa's mixed in, or even throw some carbs in there to help get through such a brutal workout.
Your legs are a large muscle group and you'll naturally expend more energy working them. Go to the Biotest store and checkout Surge Workout Fuel. If you have enough disposable income, also checkout Anaconda and MAG-10.