If I was playing in the hot and humid conditions that we have been faced with I would be carrying at least double that amount of fluid. In a tournament situation, I would have at my disposal at least 6 litres of fluid to try and maintain the highest level of concentration possible throughout the round. As mentioned earlier, each person is individual so you need to try and work out how much fluid you need to be taking on during your round of golf.
Try to avoid coffee or coca-cola, as these are high in caffeine and can worsen the situation, as can alcohol, which in my opinion should not be consumed until after the round has finished. Your nutrition on the course can also play a big factor in helping you maintain a higher level of performance. It is important to eat high energy food on the golf course and as with the fluid intake, this should be taken regularly.
Taken regularly the concoction of fluid and food will improve your round and the energy that you have left at the end of the game. The majority of golfer will blame lack of practice or the ability for rounds going wrong,